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Eight cadavers were included in this anatomical study.This study aimed to confirm the anatomical feasibility of extradural transfer of the contralateral T11 ventral root (VR) to the ipsilateral L2 level and the contralateral L1 VR to the ipsilateral L3 level to restore lower limb function in cases of paraplegia.Motor dysfunction due to hemiplegia significantly affects the daily life of patients. To date, unlike in cases of upper limb dysfunction, there are few studies on the surgical management of lower limb movement dysfunction.Eight cadavers were included in this study to confirm the feasibility of the nerve transfer. After separating the VR and dorsal root at each level, the VRs at the T11 and L1 levels were anastomosed with the VRs of L2 and L3, respectively. The length of the VRs of donor roots and the distance between the donor and recipient nerves were measured. HE staining was performed to verify the number of axons and the cross-sectional area of the VRs. Lumbar x-rays of 60 healthy adults were used to measure the distance between the donor and recipient nerves.After exposing the bilateral extradural each root, the VRs could be easily isolated from the whole root. The distance between the VRs of T11 and L2, L1, and L3 was significantly longer than the length of the donor nerve. Therefore, the sural nerve was used for grafting. The measurements performed on the lumbar x-rays of the 60 healthy adults confirmed the results. The number of axons and cross-sectional area of the VRs were measured.Our study confirmed the anatomical feasibility of transferring the VRs of T11 to L2 and that of L1 to L3 to restore lower limb function in cases of hemiplegia.5.

Study design Retrospective case series. Objective Anterior sacral meningocele (ASM) is a rare disorder. We reviewed 11 cases of congenital ASM and classified them into three types based on the anatomy and relationship between the cyst and sacral nerve roots. Summary of background data The cohort with ASM is relatively large; the classification is novel and has not been previously reported. Methods Eleven consecutive patients with ASM who underwent surgery between February 2014 and January 2019 were retrospectively analyzed. They included four males and seven females. The dorsal transsacral approach was adopted in all cases. The follow-up time was at least 3 months. Results We attempted to classify ASM into three types. Of the 11 cases, six were caudal type, two were paraneural type, and three were nerve-root type. The meningocele was ligated after exploring no nerve involvement, in Type I and II. For Type III, the herniating sac and involved nerve roots were ligated when the nerve roots were indicated as nonfunctional on neurophysiological monitoring; otherwise, the sacral nerve roots were protected and imbricated on the residual sac like a hand-in-glove, and sutured to reconstruct the nerves sleeve. Eight cases were accompanied by tethered cord syndrome (TCS); spinal cord detethering was done with one-stage operation. Ten patients' presenting symptoms improved at 3 to 6 months' follow-up; notably, constipation significantly improved. Only one case accompanied by an epidermoid cyst had a second laparoscopic surgery by a general surgeon. Conclusion Aim of surgical treatment is to obliterate the communication between the subarachnoid space and herniated sac, detether the spinal cord, and resect the congenital tumor. The new classification helps to recognize the relationship between the meningocele and sacral nerve roots, and subsequently adopt different surgical strategies. We consider the dorsal transsacral approach relatively feasible, safe, and with lower complication. Level of evidence 4.

STUDY DESIGN Prospective cohort study. OBJECTIVE The aims of this study were to evaluate the outcome of surgical and nonsurgical treatment for patients with lumbar herniated disc (LHD) or lumbar spinal stenosis (LSS) after 2 years and to identify predictors for nonsuccess. SUMMARY OF BACKGROUND DATA Studies regarding the clinician's ability to identify patients with a poor prognosis are not in concurrence and further studies are warranted. METHODS This study included 390 patients with LHD or LSS referred for surgical evaluation after unsuccessful conservative treatment. Nonsuccess was defined as a Roland-Morris Disability score above 4 (0-23) or a Numeric Rating Scale back and leg pain score above 20 (0-60). Uni- and multivariate logistic regression analyses were used to investigate potential predictive factors including sociodemographic characteristics, history findings, levels of pain and disability, and magnetic resonance imaging findings. RESULTS Rates of nonsuccess at 2 years were approximately 30% in surgically treated patients with LHD, approximately about 60% in patients with LSS for disability, and 30% and 40%, respectively for pain. For the main outcome variable, disability, in the final multiple logistic regression model, nonsuccess after surgery was associated with male sex (odds ratio [OR] 2.04, 95% confidence interval [CI]: 1.02-4.11, P = 0.04), low level of education (OR 2.60, 95% CI: 1.28-5.29, P = 0.01), high pain intensity (OR 3.06, 95% CI: 1.51-6.21, P

Study design Anatomic study in nine fresh-frozen cadavers. Objective To confirm the anatomical feasibility of transferring the extradural ventral roots (VRs) and dorsal roots (DRs) of contralateral C7 nerves to those of the ipsilateral C7 nerves respectively through a cervical posterior approach. Summary of background data The contralateral C7 nerve root transfer technique makes breakthrough for treating spastic limb paralysis. However, its limitations include large surgical trauma and limited indications. Methods Nine fresh-frozen cadavers (four females and five males) were placed prone, and the feasibility of exposing the bilateral extradural C7 nerve roots, separation of the extradural C7 VR and DR, and transfer of the VR and DR of the contralateral C7 to those of the ipsilateral C7 on the dural mater were assessed. The pertinent distances and the myelography results of each specimen were analyzed. The acetylcholinesterase (AChE) and antineurofilament 200 (NF200) double immunofluorescent staining were preformed to determine the nerve fiber properties. Results A cervical posterior midline approach was made and the laminectomy was performed to expose the bilateral extradural C7 nerve roots. After the extradural C7 VR and DR are separated, the VR and DR of the contralateral C7 have sufficient lengths to be transferred to those of the ipsilateral C7 on the dural mater. The myelography results showed that the spinal cord is not compressed after the nerve anastomosis. The AChE and NF200 double immunofluorescent staining showed the distal ends of the contralateral C7 VRs were mostly motor nerve fibers, and the distal ends of the contralateral C7 DRs were mostly sensory nerve fibers. Conclusion Extradural contralateral C7 nerve root transfer in a cervical posterior approach for treating spastic limb paralysis is anatomically feasible. Level of evidence 5.

A total of 6 formalin-fixed cadavers were included in the cadaver feasibility study.The aim was to ascertain the anatomical feasibility of extradural contralateral C7 ventral root transfer technique by cervical posterior.Upper limb spastic hemiplegia is a common sequela after stroke. In our previous study, the authors established a method by transferring contralateral C7 dorsal and ventral roots to the corresponding C7 dorsal and ventral roots on the affected side in the cervical posterior.In the present study, six formalin-fixed cadavers were dissected to confirm the anatomical feasibility. Experimental anastomosis in cadavers was conducted. The pertinent lengths of the extradural nerve roots were measured. The tissue structures surrounding regions between the extradural CC7 nerve roots and the vertebral artery were observed. The cervical magnetic resonance imaging scans of 60 adults were used to measure the distance between the donor and recipient nerves.Experimental anastomosis showed that the distance between the donor and recipient nerves was approximately 1 cm; the short segment of the sural nerve needed bridging. The distance between both exit sites of the exit of the extradural dura mater was 33.57±1.55 mm. The length of the extradural CC7 ventral root was 22.00±0.98 mm. The ventral distance (vd) and the dorsal distance (dd) in males were 23.98±1.72 mm and 30.85±2.22 mm ( P0.05), while those in females were 23.28±1.51 mm and 30.03±2.16 mm, respectively. C7 vertebral transverse process, ligaments, and other soft tissues were observed between the vertebral artery and the extradural C7 nerve root.Under the premise of less trauma, our study shows that the extradural contralateral C7 ventral root transfer technique, in theory, yields better surgical results, including better recovery of motor function and complete preservation of sensory function.5.

Study design Two fresh-frozen and six formalin-fixed cadavers were included in the study. Objective To ascertain whether transferring T9 or T11 ventral root (VR) to L2 VR and T10 or T12 VR to L3 VR in restoring lower limb function after spinal cord injury is anatomically feasible. Summary of background data Lower limb paralysis impairs the quality of the life and places burden on the whole society. However, no significant improvement in this area was achieved during recent years. Methods In the present study, two fresh-frozen and six formalin-fixed cadavers were dissected to confirm the anatomical feasibility. A limited laminectomy was performed to expose the T9-L3 extradural nerve roots. T9 and T10 VR were anastomosed to L2 and L3 VR respectively, or T11 and T12 VR were anastomosed to L2 and L3 VR respectively. The pertinent distances between the donor and recipient nerves were measured and H&E staining was used to detect the axon number and cross-section area of each VR. Results The limited incision was performed to expose the T9-L3 nerve root. According to the anatomic landmark of dorsal root ganglion, each VR could be isolated from each extradural nerve root. The T9 or T11 VR needs sural nerve graft to be transferred to L2 VR, and T10 or T12 VR also needs a nerve bridge to connect to L3 VR. The nerve numbers of T9, T10, T11, T12, L2, and L3 VRs and the sural nerves were measured respectively. The cross-section areas of T9, T10, T11, T12, L2, and L3 VRs and sural nerves were measured respectively. Conclusion Our study suggested that application of transferring T9 or T11 VR to L2 VR and T10 or T12 VR to L3 VR in restoring lower limb function is anatomically feasible.Level of Evidence: 5.

Animal experiment: a rat model of lumbar disc herniation (LDH) induced painful radiculopathies.To investigate the role and mechanism of AMP-activated protein kinase (AMPK) in dorsal root ganglia (DRG) neurons in LDH-induced painful radiculopathies.Overactivation of multiple pain signals in DRG neurons triggered by LDH is crucial to the development of radicular pain. AMPK is recognized as a cellular energy sensor, as well as a pain sensation modulator, but its function in LDH-induced pain hypersensitivity remains largely unknown.The LDH rat model was established by autologous nucleus pulposus transplantation into the right lumbar 5 (L5) nerve root. At different time points after AMPK agonist metformin (250 mg/kg/d) or mammalian target of rapamycin (mTOR) inhibitor rapamycin (5 mg/kg) intraperitoneal administration, thermal and mechanical sensitivity were evaluated by measuring paw withdrawal latency (PWL) and 50% paw withdrawal thresholds (PWT). The levels of AMPK, mTOR, and p70S6K phosphorylation were determined by Western blot. We also investigated the proportion of p-AMPK positive neurons in the right L5 DRG neurons using immunofluorescence.LDH evoked persistent thermal hyperalgesia and mechanical allodynia on the ipsilateral paw, as indicated by the decreased PWL and 50% PWT. These pain hypersensitive behaviors were accompanied with significant inhibition of AMPK and activation of mTOR in the associated DRG neurons. Pharmacological activation of AMPK in the DRG neurons not only suppressed mTOR/p70S6K signaling, but also alleviated LDH-induced pain hypersensitive behaviors.We provide a molecular mechanism for the activation of pain signals based on AMPK-mTOR axis, as well as an intervention strategy by targeting AMPK-mTOR axis in LDH-induced painful radiculopathies.N/A.

Study design Anatomic study in six formalin-fixed cadavers. Objective To determine the anatomical feasibility of transferring the S2 and S3 ventral roots (VRs) to S1 VR as a method for restoring bladder dysfunction in spinal cord injury. Summary of background data A large quantity of researches of neuroanastomosis methods have been used for treating the bladder dysfunction in spinal cord injury. However, some limitations retard the development of those studies. Methods In this study, six formalin-fixed cadavers (four males, two females) were dissected. The feasibility of exposing the S1, S2, and S3 extradural nerve roots by the limited laminectomy, isolating the VR and dorsal roots from each extradural nerve root and transferring the S2,S3 VRs to the S1 VR were assessed. The pertinent distances and the nerve cross-sectional areas in each specimen were measured. The morphology of each nerve root was observed by hematoxylin-eosin staining. Results The limited laminectomy was performed to expose the S1 to S3 extradural nerve roots. The VRs could be isolated from each extradural nerve root at the location of the dorsal root ganglion and the hematoxylin-eosin staining showed that there were some connective tissues separating the VRs from the corresponding dorsal root ganglion. The S2 and S3 VRs have sufficient lengths to be transferred to S1 VR without grafting. The mean cross-sectional area of the S1 VR was 2.60 ± 0.17 mm, and that was 1.02 ± 0.32 mm and 0.51 ± 0.21 mm of the S2 and S3 VRs, respectively. Conclusion This study demonstrated that use of the S2 and S3 VRs for extradural transfer to S1 VR for restoring bladder dysfunction is surgically feasible. Level of evidence 5.

Prospective, cross-sectional observational study.We aimed to investigate the effects of chronic cervical radiculopathy (CR) on the cross-sectional area (CSA) values of the cervical nerve roots (CNRs), median, ulnar, and radial nerves with high-resolution ultrasonography.Symptomatic nerve roots are wider than asymptomatic nerve roots due to the presence of edema. Peripheral nerves have also been shown to develop edema, fibrosis, and changes distal to the affected nerve as a result of mechanical compression. In addition according to "double-crush syndrome" hypothesis, the peripheral nerves are more sensitive to pressure, and a proximal nerve lesion makes the distal segment of the nerve more susceptible to anatomic deterioration by causing interruption in the axoplasmic conduction due to compression.Forty patients with chronic CR were included to the study. Both affected CNRs and the contralateral nerve roots (control group) were evaluated with high-resolution ultrasonography. Ulnar and median nerve CSA measurements were performed at four measurement points and radial nerve measurements at a single measurement point.CSA measurements were statistically significantly higher at the CNR of the affected side compared to the unaffected side. There was no statistically significant difference when affected and unaffected sides were compared in terms of measurements performed from median, ulnar, and radial nerves at all measurement points.The results of the present study indicate that the changes in the CNR caused by CR do not have any effect on the peripheral nerves. We did not find any affection in peripheral nerve CSA that might have been suggestive of double-crush syndrome in CR.2.

Case series.This study compared the locations of arm pain, sensory symptoms, and subjective complaints of arm weakness in patients with cervical radiculopathy from MRI confirmed C6 and C7 nerve root compression.Cervical radiculopathy is defined as arm pain, sensory and motor symptoms caused by irritation of a cervical nerve root. The C6 and C7 roots are most commonly involved, and differentiating symptoms associated with each root has proven difficult. Cervical MRI allows accurate identification of nerve root compression and therefore makes it possible to explore symptom patterns that may differentiate C6 from C7 radiculopathy.A total of 122 patients with symptoms suggestive of cervical radiculopathy were recruited. Of these, 30 patients had MRI confirmed C6 and 39 patients C7 nerve root compression. By completing a study questionnaire, patients reported specific arm weakness, and marked the location of arm pain and tingling/numbness on graphic representations of the arm. Marked areas were interpreted by superimposing a grid that divided the arm into 54 distinct areas. The frequencies of reported symptoms with C6 and C7 were totaled and then compared with likelihood rations. Power analysis calculated that 27 patients would be needed in each group based on the assumption that a 30 percentage point difference in frequency of specific symptom would be clinically useful for differentiating C6 from C7 radiculopathy.Arm pain and sensory symptoms were diffuse, and were not distinctly different for C6 or C7 radiculopathy. Some weakness was reported by 41 percent of patients, with specific descriptions of weakness having limited value for differentiating between radiculopathies.The location of pain and sensory symptoms, and specific weakness complaints associated with symptomatic C6 and C7 nerve root compression overlap to the extent that caution should be exercised when predicting root involvement based on symptoms.3.

Temporal immunohistochemistry analysis of spinal cord tissue from a rat model of cervical radiculopathy.The goal was to measure spinal endothelial and astrocytic vimentin expression after a painful nerve root compression to define spinal cellular expression of vimentin in the context of pain.The intermediate filament, vimentin, is expressed in a variety of cell types in the spinal cord and is modulated in response to neural pathologies. Early after nerve root compression spinal astrocytes become activated and blood-spinal cord barrier (BSCB) breakdown occurs in parallel with development of pain-related behaviors; these spinal responses remain activated as does the presence of pain. In addition to vimentin, glial fibrillary acidic protein (GFAP) expression is a hallmark of astrocyte activation. In contrast, vascular endothelial cells down-regulate vimentin expression in parallel with vascular breakdown. It is not known whether spinal astrocytes and endothelial cells modulate their expression of vimentin in response to a painful neural injury.Mechanical hyperalgesia was measured and spinal cord tissue was harvested at days 1 and 7 after a unilateral nerve root compression in rats. Vimentin was coimmunolabeled with GFAP to label astrocytes and von Willebrand factor (VWF) for endothelial cells in the spinal cord on the side of injury.Spinal astrocytic vimentin increases by day 7 after nerve root compression, corresponding to when mechanical hyperalgesia is maintained. Spinal endothelial vimentin increases as early as day 1 after a painful compression and is even more robust at day 7.The delayed elevation in spinal astrocytic vimentin corresponding to sustained mechanical hyperalgesia supports its having a relationship with pain maintenance. Further, since BSCB integrity has been shown to be reestablished by day 7 after a painful compression, endothelial expressed vimentin may help to fortify spinal vasculature contributing to BSCB stability.N/A.

STUDY DESIGN Controlled, interventional animal study. OBJECTIVE To examine the effect of an inhibitor of acid-sensing ion channel 3 (ASIC3) on pain-related behavior induced by application of the nucleus pulposus (NP) onto the dorsal root ganglion (DRG) in rats. SUMMARY OF BACKGROUND DATA ASIC3 is associated with acidosis pain in inflamed or ischemic tissues and is expressed in sensory neurons and NP cells. The ASIC3 inhibitor, APETx2, increases the mechanical threshold of pain in models of knee osteoarthritis or postoperative pain. However, the efficacy of APETx2 for pain relief in the NP application model remains unknown. METHODS Autologous NP was applied to the left L5 nerve root of 183 adult female Sprague-Dawley rats. The DRGs were treated with NP plus one of the following four treatments: saline solution (SM), low (0.01 μg: LD), medium (0.1 μg: MD), or high dose (1.0 μg: HD) of APETx2. Behavioral testing was performed to investigate the mechanical withdrawal threshold using von Frey hairs. Expression of nerve growth factor, hypoxia-inducible factor-1α (HIF1α), activating transcription factor-3, and ionized calcium-binding adaptor molecule-1 was evaluated using immunohistochemistry. Statistical differences among multiple groups were assessed using the Steel test, the Tukey-Kramer test, and the Dunnett test. P < 0.05 were considered significant. RESULTS The thresholds in the HD group were higher than those in the SM group at Days 14 and 21 (P

Study design This is a retrospective cases study from a prospective patient register. Objective To clarify the clinical implication regard to the survivals of motor-evoked potential (MEP) response. Summary of background data Intraoperative neurophysiological monitoring has become an essential component for decreasing the incidence of neurological deficits during spine surgeries. Significant motor-evoked potential (MEP) loss but does not vanish completely is common especially in some high-risk and complicated pediatric spine deformity surgeries. Methods A total of 1820 young patients (mean age = 12.2 years) underwent spinal deformity correction were mainly analyzed. Intraoperative monitoring (somatosensory-evoked potential, MEP, free-run electromyography, free-run electromyography) and postoperative neurologic outcomes were mainly analyzed in this study. All patients with monitoring alerts were divided into two groups: group 1, intraoperative MEP recovery group; and group 2, no obvious MEP recovery group. Moreover, the patients would be followed up strictly if he/she showed IOM alerting. The surviving MEP response was identified as significant monitoring alerts (80%-95% MEP Amp. loss) associated with high-risk surgical maneuvers. Results The results showed that there were 32 pediatric patients (group 1, 21 cases and group 2, 11 cases) presenting significant MEP monitoring alerts (80%-95% loss) relative to baseline. The patients in group 1 presented the partial/entire signal recovery from MEP alerts and they did not show spinal cord deficits postoperation. The patients in group 2 without obvious intraoperative MEP recovery showed different levels of new spinal deficits, no patient showed postoperative complete paraplegia or permanent spinal cord/nerve root deficits. Conclusion When the intraoperative MEP changes significant and persistent but without totally disappeared, the rate of postoperative neural complication is relatively low. The chance of recovery of these neurological deficits is very high. Therefore, this phenomenon may be used to predictive of nonpermanent paraplegia. Level of evidence 3.

Retrospective.The purpose was to categorize and evaluate intraoperative monitoring (IOM) failure to detect neurologic deficits occurring during spinal surgery.The efficacy of spinal cord/nerve root monitoring regarding undetected neurologic deficits is examined in a large, single institution series involving all levels of the spinal column and all spinal surgical procedures.Multimodality IOM included somatosensory-evoked potentials (SSEPs), descending neurogenic-evoked potentials (DNEPs), transcranial motor-evoked potentials (MEPs), dermatomal somatosensory-evoked potentials (DSEPs), and spontaneous and triggered electromyography (spEMG, trgEMG). We reviewed 12,375 patients who underwent surgery for spinal pathology from 1985 to 2010. There were 7178 females (59.3%) and 5197 males (40.7%); 9633 (77.8%) primary surgeries and 2742 (22.2%) revisions. Procedures by spinal level were cervical 29.7% (3671), thoracic/thoracolumbar 45.4% (5624), and lumbosacral 24.9% (3080). Age at surgery was 18 years - 72.7% (8993) and 18 years - 27.3% (3382).Forty-five of the 12,375 patients (0.36%) had false negative outcomes. False negative results by modality were as follows: spEMG (n = 22, 48.8%), trgEMG (n = 8, 17.7%), DSEP (n = 4, 8.8%), DNEP (n = 4, 8.8%), SSEP (n = 3, 6.6%), DSEP/spEMG (n = 3, 6.6%), and trgEMG/spEMG (n = 1, 2.2%). Thirty-seven patients had immediate postoperative deficits unidentified by IOM; 30 patients (81%) involved nerve root monitoring, four patients had spinal cord deficits, and three patients had peripheral sensory deficits. Eight patients had permanent neurologic deficits, six (0.048%) were nerve root and two (0.016%) were spinal cord in nature.Despite correct application and usage, IOM data failed to identify 45 (0.36%) patients with false negative outcomes out of 12,375 surgical patients. Eight patients (0.064%) of these 45 patients had permanent neurologic deficits, six patients had nerve root deficits in nature and two patients had spinal cord deficits. Although admittedly small, this represents the risk of undetected neurologic deficits even when properly using IOM. Deficits are at a higher risk to remain unresolved when not detected by IOM.4.

Study Design. Part 1: A randomized, single-blind study on the effect of contralateral knee extension on sensations produced by the slump test (ST) in asymptomatic subjects. Part 2: A cadaver study simulating the nerve root behavior of part 1. Objective. Part 1: Test if contralateral knee extension consistently reduces normal stretch sensations with the ST. Objective. Part 2: Ascertain in cadavers an explanation for the results. Summary of Background Data. In asymptomatic subjects, contralateral knee extension reduces stretch sensations with the ST. In sciatica patients, contralateral SLR also can temporarily reduce sciatica. We studied this methodically in asymptomatic subjects before considering a clinical population. Methods. Part 1: Sixty-one asymptomatic subjects were tested in control (ST), sham, or intervention (contralateral ST) groups and their sensation response intensity compared. Methods. Part 2: Caudal tension was applied to the L5 nerve root of 3 cadavers and tension behavior of the contralateral neural tissue recorded visually. Results. Part 1: Reduction of stretch sensations occurred in the intervention group but not in control and sham groups (P ≤ 0.001). Results. Part 2: Tension in the contralateral lumbar nerve roots and dura reduced in a manner consistent with the responses in the intervention (contralateral ST) group. Conclusion. Part 1: In asymptomatic subjects, normal thigh stretch sensations with the ST reduced consistently with the contralateral ST, showing that this is normal and may now be compared with patients with sciatica. Conclusion. Part 2: Contralateral reduction in lumbar neural tension with unilateral application of tension-producing movements also occurred in cadavers, supporting the proposed explanatory hypothesis.

This was a controlled, interventional animal study.This study aimed to investigate the thermal injury of nerve root by cauterization near the nerve root and to identify the prevention or rescue procedure of nerve root injury.In spine surgery, bipolar cauterization of epidural venous plexus near the nerve root is an essential procedure to control bleeding. Although a potential risk of neurological thermal damage exists, the underlying mechanism and prevention have not been elucidated.Temperature measurement and histological evaluation after bipolar cauterization near the posterior branch of the nerve root were performed using a rabbit model. Subsequently, the effect of saline irrigation or changing the direction of bipolar forceps to reduce thermal elevation during bipolar cauterization was evaluated. Finally, the effectiveness of locally injected corticosteroid after bipolar cauterization was evaluated.After bipolar cauterization, temperature of the surrounding site reached 60.9 °C, and 47.8% of the nerves were histologically injured. Using saline irrigation, thermal elevation was significantly suppressed up to 42.7 °C (P 0.01), and no nerve was histologically injured. When bipolar cauterization was performed in the perpendicular direction, temperature of the surrounding site reached only 40.4 °C (P 0.01). Locally injected corticosteroid reduced the incidence of nerve injury to 25.0%. However, a significant increase in nerve damage remained compared with the sham group (P 0.01).Bipolar cauterization near the nerve roots can increase the temperature of nerve roots and cause thermal nerve root injury, despite no accidental direct nerve root injury. Using saline irrigation, or setting bipolar forceps perpendicular to nerve roots, thermal elevation could be suppressed and nerve injury could be prevented. Therefore, it is recommended that surgeons set bipolar forceps perpendicular to nerve roots or use saline irrigation for the prevention of nerve root injury.N/A.

Study design A retrospective review of prospectively collected data. Objective To confirm the feasibility of using anterior to dorsal root entry zone myelotomy (ADREZotomy), a new surgical approach, for the treatment of ventrolateral deep intramedullary spinal cord cavernous malformation (ISCCMs). Summary of background data Surgical removal of ventrolateral deep ISCCMs is highly risky and remains problematic. Methods The authors performed a retrospective study exploring the surgical removal of ventrolateral intrinsic ISCCMs using ADREZotomy in 10 patients. The Frankel grading system was used to evaluate the patients' neurological function at the preoperative, postoperative and follow-up stages. American Spinal Injury Association Scale scores at the preoperative and postoperative were also obtained. The patient characteristics and surgical outcomes were analyzed. The indication, operative steps, complications, and anatomical basis of the myelotomies were described and discussed. Results In total, nine (90%) patients presented with mild symptoms before surgery. Gross total resections were performed in all 10 patients. Immediately after surgery, the neurological function of eight (80.0%) patients remained the same. One patient improved and one (10%) patient worsened. There were no other immediate or delayed complications related to the surgical procedure. No decrease of total American Spinal Injury Association sensory scores was observed. The follow-up neurological function evaluation showed that two (20%) patients improved from a Frankel grade of D to E and eight (80.0%) patients were stable. No recurrences or other additional neurological deterioration was observed. Conclusion Surgical removal of ventrolateral deep ISCCMs can be feasible using proper surgical techniques. ADREZotomy is a minimally invasive technique for the removal of cervical and thoracic ventrolateral deep ISCCMs, without disrupting the important spinal cord tracts or the need to broadly expose bone. Level of evidence 4.

STUDY DESIGN Measurement of local pressure of the intervertebral foramina. OBJECTIVE To evaluate the pathophysiological effects of lumbar instrumentation surgery on lumbosacral nerve roots in the vertebral foramen. SUMMARY OF BACKGROUND DATA The physiological states of lumbosacral nerve roots in the vertebral foramen remain controversial. METHODS From 2000 to 2012, 11 of 710 patients with L4 degenerative spondylolisthesis failed to develop postoperative radiculopathy because of intraoperative pedicle screw malposition (L5: 10, L4: 1). We prospectively evaluated the local pressure at the L4-L5 and L5-LS vertebral foramina in 18 patients with L4 degenerative spondylolisthesis. All patients underwent L4-L5 posterolateral fusion (PLF) with L3-L4-L5 laminotomy. Intraoperatively, local pressure of the intervertebral foramen was measured using a catheter pressure transducer while changing the lumbar spine posture, and the measurement was performed before and after L4-L5 PLF. RESULTS The local pressures at the L4-L5 vertebral foramen were 29.74 ± 16.26 and 51.57 ± 23.18 mm Hg (before fixation), and 39.13 ± 17.69 and 41.71 ± 17.94 mm Hg (after fixation) in the lumbar spine neutral and extension postures, respectively. The local pressure before fixation increased significantly during lumbar spine extension (P < 0.001), although the value after fixation was almost identical. The local pressures at the L5-LS vertebral foramen were 26.91 ± 18.16 and 54.36 ± 26.67 mm Hg (before fixation), and 24.82 ± 17.1 and 58.46 ± 32.78 mm Hg (after fixation) in the lumbar spine neutral and extension postures, respectively. The local pressure before and after fixation increased significantly during lumbar spine extension (P < 0.001), and the values after fixation were higher than those before fixation. CONCLUSION The local pressure at the L4-L5 vertebral foramen did not change during lumbar extension after L4-L5 PLF, whereas the local pressure at the L5-LS vertebral foramen was significantly increased during lumbar extension after L4-L5 PLF. Our results suggested that the nerve roots caudal to the fixed segments may be exposed to higher external dynamic stresses after lumbar instrumentation surgery. LEVEL OF EVIDENCE 4.

Anatomical Study.Determine if shoulder depression (eg, taping the shoulders) might result in C5 nerve traction and subsequent injury.Postoperative C5 nerve palsy is a recognized entity that is still often enigmatic. Inferior shoulder depression is usually employed to assist with surgical visualization during cervical spine procedures.In the supine position, 10 adult fresh frozen human cadavers underwent dissection of the spinal cord and its adjacent dorsal, ventral roots, and spinal nerves from C4 to T1. In the supine position, the head was rotated ipsilaterally, contralaterally, and in lateral flexion. The shoulder was elevated, retracted, protracted, and depressed all with direct observation of nerve roots, intradural ventral/dorsal rootlets, or the spinal cord. The effects of these movements upon the cervical nerve rootlets were measured.The greatest displacement of nervous tissue was generated by shoulder depression and occurred primarily at the intradural rootlet level. The nerve rootlets that underwent the greatest average displacement were found at C5, with a decreasing gradient to C7 and no gross motion at C8 or T1. With maximal shoulder depression, C5-C7 rootlet tension produced cord movement to the ipsilateral side, touching the dura mater covering the lateral vertebral column with the C5 nerve root moving farthest.Shoulder depression is often used during cervical spine surgery. In cadavers, shoulder depression causes significant tension and displacement of the C5 nerve rootlets, and in the extreme, cord displacement to the ipsilateral side. This could be a mechanism for injury, putting patients at greater risk for postoperative C5 palsy.5.

Study design Systematic review and meta-analysis. Objective To evaluate the clinical and functional outcomes of transection of the C2 roots during C1 lateral mass screw placement for atlantoaxial fixation. Summary of background data Transection of the C2 nerve roots has been recommended during atlantoaxial fixation to facilitate C1 lateral mass screw placement and possibly reduce postoperative occipital neuralgia, although this practice remains controversial. Methods We searched MEDLINE, EMBASE, Web of Science, and the Cochrane Library for studies evaluating the outcomes of C1-2 fixation involving sacrifice of the C2 roots. We calculated transformed proportions with 95% confidence intervals (CI) for the outcomes of occipital neuralgia, numbness, bony fusion, and procedural morbidity. For studies comparing C2 transection with nerve sparing surgery, we performed meta-analyses for the outcomes of occipital neuralgia, occipital numbness, blood loss, and operative time. Results Eight observational studies (N = 393) met eligibility criteria. The rate of postoperative occipital neuralgia among included studies was 0% to 25%; occipital numbness, 6.7% to100%; bony fusion, 96.7% to 100%; and procedural morbidity, 0% to 14.3%. Among comparative studies, C2 transection was associated with a higher rate of occipital numbness [odds ratio (OR) 178.6 (95% CI 26.6 to 1198.4)], lower blood loss [mean difference (MD) -195.3 mL (95% CI -317.7 to -72.8 mL)] and shorter operative times [MD -57.5 mins (95% CI -76.9 to -38.2 mins)] than when the C2 roots were spared. We found no difference in rates of occipital neuralgia [OR 1.44 (95% CI 0.45 to 4.68)]. Conclusion Transection of the C2 nerve roots appears to be a viable, safe option when undertaking placement of C1 lateral mass screws. The procedure is associated with reduced operative duration and blood loss, increased rate of occipital numbness, and no change in the rate of occipital neuralgia. However, given the relatively low quality of evidence, prospective, controlled studies to evaluate this strategy are recommended. Level of evidence N /A.

Study design Review and grade the morphology of the C1-C2 neural foramina, from the MR images of patients who underwent C1-C2 spinal surgery, and determine the relationship with ON. Objective To evaluate the feasibility of MRI for C1-C2 neural foramen evaluation with a new grading system and to correlate the C1-C2 neural foramen grade with ON. Summary of background data There have been no MRI studies of patients with and without ON in relation to C2 nerve root ganglion findings. Methods Among the registry of 124 patients who underwent C1-C2 spinal surgery between July 2004 and May 2012 in Seoul National University Bundang Hospital, we enrolled 101 patients who had information about ON and a relevant preoperative cervical spine MR image. A total of 202 neural foramina were evaluated with our new C1-C2 neural foramen grading system (grade, 0-3) using consensus reading by 2 experienced radiologists who were blinded to the clinical information. The relationship between the C1-C2 grading system and ON was assessed using a χ test and Fisher exact test. Inter- and intraobserver reliability agreement was assessed using the κ statistic. Results All C1-C2 neural foramina were delineated on T2 parasagittal images. Among 202 C1-C2 neural foramina, grade zero was found in 49 foramina (24.3%), grade 1 in 95 (47.0%), grade 2 in 30 (14.9%), and grade 3 in 28 (13.9%). Grade 1 stenosis was most frequently noted. The grade 2 group had the most frequent prevalence of ON (43.3%), followed by grade 3 (35.7%), grade zero (30.6%), and grade 1 (29.5%). However, the relationship between the grade and ON was not statistically significant. Inter- and intraobserver agreements were substantially high. Conclusion C1-C2 neural foramina can be depicted on MR image. However, the relationship between the new grading system for C1-C2 neural foramina and ON was not statistically significant. Level of evidence 4.

STUDY DESIGN: Single-center retrospective study. OBJECTIVE: We examined whether extremely wide and asymmetric anterior decompression causes postoperative C5 palsy. SUMMARY OF BACKGROUND DATA: Postoperative C5 palsy is a complication of cervical decompression surgery. We hypothesized that C5 palsy may be caused by nerve root impairment through extremely wide and asymmetric dural expansion due to unilateral predominant wide anterior decompression with concomitant C4-C5 foraminal stenosis. METHODS: The study included 32 patients with postoperative C5 palsy from a cohort of 459 patients who underwent anterior cervical decompression and fusion at the C4-C5 disc level for cervical myelopathy. The 64 upper extremities were divided into 2 groups according to palsy side (n = 35) or nonpalsy side (n = 29). Also, to correlate radiological findings, 66 consecutive patients who underwent anterior cervical decompression and fusion without postoperative C5 palsy were selected as control. RESULTS: In patients with C5 palsy, the unilateral decompression width on the palsy side was significantly larger than that on the nonpalsy side (8.63 vs. 6.92 mm, P = 0.0003). In addition, the decompression width was significantly larger (15.69 vs. 14.38 mm, P = 0.02), the diameter of the C4-C5 foramen was significantly smaller (2.73 vs. 3.24 mm, P = 0.0008), the anterior spinal cord shift was significantly smaller (0.14 vs. 0.73 mm, P< 0.0001), and significant decompression asymmetry (0.74 vs. 0.89, P = 0.0003) was present in the patients with C5 palsy compared with controls. CONCLUSION: Extremely wide and asymmetric decompression concomitant with pre-existing C4-C5 foraminal stenosis may cause postoperative C5 palsy. Our findings should be valuable for surgeons considering anterior cervical decompression and fusion that includes the C4-C5 level. Surgeons should consider restriction of the decompression width to less than 15 mm and avoiding asymmetric decompression to reduce the incidence of C5 palsy.

Study design Exposure to nucleus pulposus and displacement of intraspinal nervous structures with assessment of spontaneous behavioral changes in rats. Objective To develop a controlled, experimental model for nerve root injury. Summary of background data There are a number of experimental models presented for studies on radiculopathies. One frequently used model is based on exposure to nucleus pulposus and displacement of the dorsal root ganglion (DRG). However, it is clinically more common that the nerve roots are displaced/compressed than the DRG. In this study, we developed a model for displacement of the nerve root by modifying the DRG model. Methods After removing the left L3-L4 facet joint, the underlying disc was punctured, and the L4 nerve root was displaced laterally by an injection needle (n = 10). In sham experiments, the same procedure was performed without disc puncture and displacement (n = 10). In 10 rats, the left L4-L5 facet joint was removed. The underlying disc was punctured and the L4 DRG was displaced medially by an injection needle. Assessment of spontaneous behavioral changes was performed on days 1, 3, 7, 14, and 21, postsurgery. Results There was a clear increase in duration of the behavior "unloading of the paw" after displacement of the DRG that was most pronounced on day 1 and then gradually declined. There was a similar pattern for this behavior induced by nerve root displacement, although the duration was higher than that for the DRG displacement. No apparent trends in behavioral changes were observed for the other behaviors studied. Conclusion Displacement of the nerve root induced more changes in the pain behavior than displacement of the DRG, but only for the behavior unloading of the paw. Because nerve root injury is more common than DRG injury, this model may be more clinically relevant than the DRG model. Level of evidence N/A.

STUDY DESIGN Experimental animal study. OBJECTIVE This study investigated whether nitric oxide (NO) mediated protein nitration is involved in the pathogenesis of radiculopathy and whether the symptoms can be relieved by its suppression. SUMMARY OF BACKGROUND DATA It has been reported that nitration of protein mediated by NO is involved in the degenerative neurological disorders, but its involvement is not clear in the radiculopathy. METHODS Two kinds of rat models of radiculopathy were used. Radiculopathy was induced either by ligation of spinal nerve roots or transplantation of autologous nucleus pulposus. In separate groups of rats, aminoguanidine, a potent nitric oxide synthetase inhibitor, was administered just before induction of radiculopathy, to suppress NO production and resultant nitration of protein. Sensation of the hind limb was evaluated by plantar stimulation test, and motor weakness was assessed by observation of gait pattern. Nitrotyrosine, product of protein nitration, was assayed quantitatively by Western immunoblotting. RESULTS Mechanical allodynia was observed in both compression and nucleus pulposus groups, but motor weakness was observed only in the compression group. Preoperative administration of aminoguanidine attenuated mechanical allodynia and motor weakness. Optical densities of nitrotyrosine bands increased significantly in radiculopathy groups, but they were lowered by administration of aminoguanidine. CONCLUSION NO mediated protein nitration contributes to the development of both types of radiculopathies. Suppression of NO production can decrease protein nitration and relieve neural dysfunctions of radiculopathy. LEVEL OF EVIDENCE N/A.

STUDY DESIGN A retrospective clinical data analysis. OBJECTIVE To investigate the factors related to postoperative neurological deficits after nerve root resection in the treatment of spinal intradural schwannoma. SUMMARY OF BACKGROUND DATA Neurological deficits could be observed after resection of tumor-involved nerve roots in spinal intradural schwannoma. Thus, it is important to find the factors related to postoperative neurological deficits. METHODS Clinical and pathological data were selected from patients underwent total resection of the solitary spinal intradural schwannoma from T11 to S. Patients were divided into the postoperative neurological deficits positive group (PND group, n = 12) and negative group (non-PND group, n = 52). Clinical features including age, sex, duration of disorders, diabetes, preoperative visual analogue scale (VAS) and SF-36 score, preoperative symptoms, tumor size, tumor location, and immunostaining results were analyzed. RESULTS Age, sex, duration of disorders, diabetes, preoperative VAS and SF-36 score, tumor length, and tumor-occupied ratio were not significantly different between the two groups (P > 0.05). Lower extremity pain, sensory disturbance, and motor disturbance were found in 25.0%, 50.0%, and 75.0% of patients in the PND group and 76.9%, 17.3%, and 7.7% of patients in the non-PND group, respectively, and the results were significantly different (P

Study Design. Electrophysiological recordings were obtained from proprioceptors in deep lumbar paraspinal muscles of anesthetized cats during high-velocity low-amplitude spinal manipulation (HVLA-SM). Objective. To determine how thrust direction of an HVLA-SM affects neural input from back musculature. Summary of Background Data. A clinician's ability to apply the thrust of an HVLA-SM in a specified direction is considered an important component of its optimal delivery. However, previous biomechanical studies indicate that the shear force component of the thrust vector is not actually transmitted to paraspinal tissues deep to the thoracolumbar fascia because the skin–fascia interface is frictionless. Methods. Neural activity from muscle spindles in the multifidus and longissimus muscles was recorded from L6 dorsal rootlets in 18 anesthetized cats. After preload to the spinal tissues, HVLA-SMs (100-ms thrust duration) were applied through the intact skin overlying the L6 lamina. Thrusts were applied at angles oriented perpendicularly to the back and obliquely at 15° and 30° medialward or cranialward using a 6 × 6 Latin square design with three replicates. The normal force component was kept constant at 21.3 N. HVLA-SMs were preceded and followed by simulated spinal movement applied to the L6 vertebra. Changes in mean instantaneous discharge frequency (ΔMIF) of muscle spindles were determined both during the thrust and spinal movement. Results. ΔMIFs during the HVLA-SM thrust were significantly greater in response to all thrust directions compared with the preload alone, but there was no difference in ΔMIF for any of the thrust directions during the HVLA-SM. HVLA-SM decreased some of the responses to simulated spinal movement but thrust direction had no effect on these changes. Conclusion. The shear force component of an HVLA-SM's thrust vector is not transmitted to the underlying vertebra sufficient to activate muscle spindles of the attached muscles. Implications for clinical practice and clinical research are discussed. Conclusion. Level of Evidence: N/A

Study design A prospective clinical study. Objective To elucidate the histomorphological features and clinical significance of the epidural membrane (EM) in the cervical spine based on operative and histological findings. Summary of background data The anatomical features of the EM have been mostly discussed on the basis of cadaver studies in the whole spine. However, the histomorphological features and clinical significance of the EM in the cervical spine based on operative findings have never been reported. Methods Eighty-seven patients with cervical spondylotic myelopathy who had undergone an expansive open-door laminoplasty under microscopy were evaluated with a more than 2-year follow-up period. The most damaged spinal segment was determined in each patient from the preoperative neurological and image findings along with the remaining symptoms at follow-up. The morphological features of the EM were observed and recorded in each patient during decompression. For histology, specimens of common and remarkable types of the EM obtained from 16 patients were examined. Results The age at surgery averaged 64.5 years; there were 58 men and 29 women. With regard to the most damaged spinal segment, there were 14 cases at the C3-C4 level, 37 at the C4-C5 level, 32 at the C5-C6 level, and 4 at the C6-C7 level. The EM was an adipo-fibro-vascular tissue with various histomorphologies, blending with the periradicular sheath. Some EMs showed notable findings: obstructing dural tube expansion (13 cases, 14.9%), compressing a nerve root or disturbing its mobility (4 cases, 4.6%), and the combined type (1 case, 1.1%). All of them were located at approximately the most damaged spinal segment. In addition, some EMs had interesting histological features, such as harboring many small arteries, calcified debris, and metaplastic bone fragments. Conclusion The EM can develop into remarkable structures with spondylosis and aging in patients with cervical spondylotic myelopathy, affecting surgical outcomes as well as successful decompression procedures. A sound understanding of the histomorphological features of the EM is required to obtain satisfactory surgical outcomes in the limited field afforded by minimally invasive surgery.

BACKGROUND CONTEXT: The dural sac is anchored within the vertebral canal by connective tissue called meningovertebral ligaments in the epidural space. During flavectomy and laminectomy, inadvertent disruption of the dorsal meningovertebral ligaments may lead to dura laceration and cerebrospinal fluid (CSF) leaks. All the described dorsal meningovertebral ligaments were located in the lumbar region. A rare study is available about dorsal meningovertebral ligaments of the cervical spinal dura to the adjacent vertebrae. PURPOSE: To identify and describe the dorsal meningovertebral ligaments at each cervical level and discuss their clinical significance. STUDY DESIGN: A dissection-based study of 22 embalmed cadavers. METHODS: The anatomy was studied in 22 whole cervical cadavers (11 females, 11males), prepared with formaldehyde, whose ages at the time of death ranged from 55 to 78 years. The vertebral canal was divided to expose the dural sac and the spinal nerve roots. At all levels of the cervical vertebra, the morphology, quantity, origin, insertion, and spatial orientation of the dorsal meningovertebral ligaments were determined and the length, width or diameter, and thickness of the ligaments were measured with vernier calipers. RESULTS: The dorsal meningovertebral ligaments in the cervical region anchored the posterior dural sac to the ligamentum flavum or laminae. The number of attachment points on the ligamentum flavum was relatively larger than that on the lamina, and the occurrence rate of dorsal meningovertebral ligaments was 100% at C1‐C2 and C4‐‐C5. The thickest ligaments were observed at the C1 and C2 vertebrae. The length of the ligaments varied from 1.50 to 35.22 mm, and the orientation of the ligaments mostly was craniocaudal. The morphology of the dorsal meningovertebral ligaments was divided into four types: strip type, cord type, grid type, and thin slice type. CONCLUSIONS: In the cervical spine, the dorsal meningovertebral ligaments exist between the posterior dural sac and the ligamentum flavum or lamina. The dorsal meningovertebral ligaments may be of clinical importance to surgeons. Dissecting the dorsal meningovertebral ligaments before the cervical flavectomy and laminectomy may be an important step in reducing postoperative dura laceration and CSF leaks, which may result in significant benefits for patients and health-care organizations. 2014 Elsevier Inc. All rights reserved.

Study design Retrospective review of 750 consecutive multilevel cervical spine decompression surgeries performed by a single spine surgeon. Objective To determine the incidence of C5 palsy in a large consecutive series of multilevel cervical spine decompression procedures. Summary of background data Palsy of the C5 nerve is a well-known potential complication of cervical spine surgery with reported rates ranging from 0% to 30%. The etiology remains uncertain but has been attributed to iatrogenic injury during surgery, tethering from shifting of the spinal cord, spinal cord ischemia, and reperfusion injury of the spinal cord. Methods We included patients undergoing multilevel cervical corpectomy, corpectomy with posterior fusion, posterior laminectomy and fusion, and laminoplasty. Exclusion criteria included lack of follow-up data, spinal cord injury preventing preoperative or postoperative motor testing, or surgery not involving the C5 level. Incidence of C5 palsy was determined and compared to determine whether significant differences existed among the various procedures, patient age, sex, revision surgery, preoperative weakness, diabetes, smoking, number of levels decompressed, and history of previous upper extremity surgery. Results Of the 750 patients, 120 were eliminated on the basis of the exclusion criteria. The 630 patients included in the analysis consisted of 292 females and 338 males. The mean age was 58 years (range, 19-87). The incidence of C5 nerve palsy for the entire group was 42 of 630 (6.7%). The incidence was highest for the laminectomy and fusion group (9.5%), followed by the corpectomy with posterior fusion group (8.4%), the corpectomy group (5.1%), and finally the laminoplasty group (4.8%), although these differences did not reach statistical significance. There was a significantly higher incidence in males (8.6% vs. 4.5%, P = 0.05). Conclusion Incidence of C5 nerve palsy after cervical spine decompression was 6.7%. This is consistent with previously published studies and represents the largest series of North American patients to date. There is no statistically significant difference in incidence of C5 palsy based on surgical procedure, although there was a trend toward higher rates with laminectomy and fusion.

STUDY DESIGN A case report of a rare symptomatic, idiopathic, noncommunicating intradural arachnoid cyst (IAC) of the proximal part of the S1 nerve root (NR). OBJECTIVE To discuss the possible pathophysiology, clinical and magnetic resonance imaging (MRI) presentation, intraoperative findings, and follow-up of IAC of the proximal part of the S1 NR. SUMMARY OF BACKGROUND DATA Rare variety of the Nabors's Type 3 spinal IAC. The etiopathogenesis are uncertain. Surgical NR decompression with extirpation of the cyst is the treatment of choice. METHODS A 37-year-old woman clinically presented as monoradiculopathy with a 9-month history of progressive, posture-dependent radicular pain, paresthesia and hypoesthesia in the right S1 dermatome, and mild weakness of the ipsilateral plantar flexors. Magnetic resonance imaging (MRI) showed a noncommunicating IAC of the proximal part of the S1 NR on the right side. Surgical exploration through the ipsilateral L5-S1 hemilaminectomy was performed with microsurgical arachnolysis of the compressed and stretched S1 NR fascicles that surrounded the cyst, during which the cyst spontaneously collapsed. The remnant of the cyst wall was extirpated and histopathology confirmed the diagnosis. RESULTS After surgery an excellent clinical outcome was archived: the leg pain was no longer present and the paraesthesia, hypoesthesia, and motor weakness were resolved within 3 months. At 12 months of follow-up, the patient continues to be completely asymptomatic with no evidence of recurrence on MRI. CONCLUSION A rare case of symptomatic, idiopathic, noncommunicating IAC of the proximal part of the S1 NR has been presented. Early recognition and treatment resulted in complete symptom resolution, with preservation of the full working capacity and good quality of life. Isolated monoradiculopathy with progressive, posture-dependent radicular pain seem to be typical clinical findings for such a lesion. Attending physicians should always be mindful of this fact in the total clinical evaluation of such cases.

Study Design. Normal rabbits and paraplegic rabbits were subjected to an acute, complete spinal cord injury (SCI) event. In a subset of paraplegic rabbits, an electrode was implanted to provide electrical stimulation of the sacral 3 (S3) nerve root. Objective. To investigate the effect of sacral nerve root stimulation on the treatment and prevention of bacterial translocation from the gut and endotoxemia in rabbits after an acute and complete SCI. Summary of Background Data. It has been demonstrated that bacterial translocation and endotoxemia were complications after a SCI-induced paraplegia due to intestinal tract dysfunction. Sacral nerve root stimulation has been shown to improve intestinal tract motion and defecation, however, the treatment and prevention of bacterial translocation originating in the gut with sacral nerve root stimulation has not been confirmed or tested after an acute, complete SCI. Methods. A model of paraplegia was established with injury of the spinal cord of rabbits. The experimental group (EG) included paraplegic rabbits that received electrical stimulation of the S3 nerve root. The paraplegic control group (CG) (paraplegic rabbits) and the normal control group (uninjured rabbits) did not receive electrical stimulation. Under aseptic conditions, samples of blood, liver, spleen, and mesenteric lymph nodes were collected at 24, 48, and 72 hours after SCI. Samples were analyzed with bacterial cultures and endotoxin assays. The morphology and ultrastructure of the small intestine was also analyzed. Results. Bacterial translocation and endotoxemia were detected in both the paraplegic CG and the EG. In paraplegic rabbits, S3 nerve root stimulation improved defecation (F = 19.974, P = 0.000), reduced the levels of endotoxins present in the blood to normal levels (F = 16.786, P = 0.000), and reduced the incidence of bacterial translocation from the gut (n = 18, P < 0.01). In contrast, the endotoxin content and incidence rate of bacterial translocation in the gut for the paraplegic CG following SCI increased. Pathologic changes became more apparent and remarkable with the constipation and endotoxemia aggravating in the CG, however, these conditions were not apparent in the EG. Conclusion. After SCI, S3 nerve root stimulation improved intestinal tract motion and defecation in paraplegic rabbits. Furthermore, the incidence rate of bacterial translocation from the gut and endotoxemia were reduced. Thus, the risk systemic inflammatory response syndrome and multiple organ dysfunction syndrome can also be reduced.

Study design The effects of exogenous 5-hydroxytryptamine (5-HT), tumor necrosis factor(TNF)-α, 5-HT + TNF in combination, and autologous nucleus pulposus (NP) at dorsal root ganglion (DRG) were examined using rat models. Objective To examine the interaction of 5-HT with TNF for pain-related behavior in a rat lumbar disc herniation (LDH) model. Summary of background data 5-HT and TNF have been shown to play roles in sciatica in lumbar disc herniation as chemical factors. Methods Adult female Sprague-Dawley rats were divided into six groups: 5-HT group, TNF group, 5-HT + TNF (combination) group, NP group, control group, and naive group. Von Frey tests were used for pain-related behavior testing. Expressions of activating transcription factor 3 and calcitonin gene-related peptide (CGRP) were evaluated immunohistochemically. Expressions of TNF, TNF receptor 1 (TNFR1), and 5-HT2A receptors in the left L5 DRG were examined using western blotting. Plasma levels of 5-hydroxyindole acetic acid, a metabolite of 5-HT, were measured. Results Mechanical withdrawal thresholds were significantly decreased in the 5-HT, TNF, combination, and NP groups compared with controls. Thresholds recovered after 14 days in the 5-HT and TNF groups, and after 28 days in the combination group. Exogenous 5-HT and TNF to the nerve root induced pain-related behavior and lasted for a shorter period compared with combination and NP groups. Activating transcription factor 3- and calcitonin gene-related peptide-immunoreactive DRG neurons were significantly increased only in the early phase in 5-HT, TNF, combination, and NP groups. TNF induced 5-HT2A receptor expressions in the DRG, while 5-HT induced TNF and TNF receptor 1 expressions. Conclusion The present findings suggest that both 5-HT and TNF induce pain-related behavior and interact with each other to prolong pain-related behavior in a rat LDH model.

Study design Ten patients with a spinal tumor of the lower lumbar spine underwent total en bloc spondylectomy (TES) by combined posterior-anterior approach. The oncological and neurologic results are analyzed. Objective To describe the surgical technique and evaluate the clinical outcome of this surgery. Summary of the background data TES at lower lumbar spine is technically challenging because of its anatomy such as the presence of major vessels and lumbosacral plexus nerves. Methods Six aggressive benign tumors and 4 solitary spinal metastases involving L4 or L5 were treated. The approache of operative procedure are discussed as follows: Posterior approach: Dissection of the lumbar nerve roots to the conjunction of the adjacent nerves were performed after en bloc laminectomy by T-saw pediculotomy. The psoas muscle was dissected away, from the vertebral body. The posterior halves of the anterior column at the craniocaudal adjacent levels of the lumbar tumor were cut. Anterior approach: Major vessels were dissected from the vertebral body. Anterior halves of the anterior column were cut at the corresponding levels. The tumor vertebral body was removed en bloc, followed by anterior spinal reconstruction. Results Seven of 10 cases had no evidence of disease at 57 months on average, 1 case was alive with disease at 66 months, 1 case had death of disease at 42 months, and 1 case had death of another disease at 14 months after surgery. All patients improved or preserved neurologic in the last follow up. The resected specimen of vertebral bodies and laminae showed marginal or wide margin in all cases, although pedicles showed intralesional margin in 8 cases. No local recurrence was observed during lifetime with mean 52 months. Conclusion TES for spinal tumor of L4 or L5 preserving lumbar nerves was achieved by combined posterior- anterior approach.

Study design Cross-sectional study with prospective recruitment. OBJECTIVE.: To determine the accuracy of the physical examination for the diagnosis of midlumbar nerve root impingement (L2, L3, or L4), low lumbar nerve root impingement (L5 or S1) and level-specific lumbar nerve root impingement on magnetic resonance imaging, using individual tests and combinations of tests. Summary of background data The sensitivity and specificity of the physical examination for the localization of nerve root impingement has not been previously studied. Methods Sensitivities, specificities, and likelihood ratios (LRs) were calculated for the ability of individual tests and test combinations to predict the presence or absence of nerve root impingement at midlumbar, low lumbar, and specific nerve root levels. Results LRs ≥5.0 indicate moderate to large changes from pre-test probability of nerve root impingement to post-test probability. For the diagnosis of midlumbar impingement, the femoral stretch test (FST), crossed FST, medial ankle pinprick sensation, and patellar reflex testing demonstrated LRs ≥5.0 (LR ∞). LRs ≥5.0 were observed with the combinations of FST and either patellar reflex testing (LR 7.0; 95% confidence interval [CI] 2.3-21) or the sit-to-stand test (LR ∞). For the diagnosis of low lumbar impingement, the Achilles reflex test demonstrated an LR ≥5.0 (LR 7.1; 95% CI 0.96-53); test combinations did not increase LRs. For the diagnosis of level-specific impingement, LRs ≥5.0 were observed for anterior thigh sensation at L2 (LR 13; 95% CI 1.8-87); FST at L3 (LR 5.7; 95% CI 2.3-4.4); patellar reflex testing (LR 7.7; 95% CI 1.7-35), medial ankle sensation (LR ∞), or crossed FST (LR 13; 95% CI 1.8-87) at L4; and hip abductor strength at L5 (LR 11; 95% CI 1.3-84). Test combinations increased LRs for level-specific root impingement at the L4 level only. Conclusion Individual physical examination tests may provide clinical information that substantially alters the likelihood that midlumbar impingement, low lumbar impingement, or level-specific impingement is present. Test combinations improve diagnostic accuracy for midlum-bar impingement.

Study design This study is aimed to investigate the changes of nerve root functions during the straight leg raising (SLR) test in vivo. Objective To investigate the relationship between nerve root movement and the electrophysiological values during an intraoperative SLR test. Summary of background data The SLR test is one of the most significant signs for making a clinical diagnosis of lumbar disc herniation. A recent study showed that intraradicular blood flow apparently decreased during the SLR test in patients with disc herniation. Methods The study included 32 patients who underwent microdiscectomy. During the surgery, the nerve root motion affected by the hernia was observed during the SLR test. The patients' legs were allowed to hang down to the angle at which sciatica had occurred and the change of nerve root action potentials was measured. After removal of the hernia, a similar procedure was repeated. The periradicular specimens collected during surgery were examined by light and electron microscope. Results In all patients intraoperative microscopy revealed that the hernia was adherent to the dura mater of the nerve roots. During the SLR test, the limitation of nerve root movement occurred by periradicular adhesive tissue and amplitude of action potential showed a sharp decrease at the angle that produced sciatica. After removal of the hernia, all the patients showed smooth gliding of the nerve roots during the test, and there was no marked decrease of amplitude. Our data suggest that temporary ischemic changes in the nerve root cause transient conduction disturbances. Pathologic examination showed that the periradicular tissue consisted of the granulation with vascularization and many inflammatory cell infiltrations. Conclusion The presence of periradicular fibrosis will compound the nerve root pain by fixing the nerve in one position, thereby increasing the susceptibility of the nerve root to tension or compression.

Retrospective case-referent study.To assess whether the new sedimentation sign discriminates between nonspecific low back pain (LBP) and symptomatic lumbar spinal stenosis (LSS).In the diagnosis of LSS, radiologic findings do not always correlate with clinical symptoms, and additional diagnostic signs are needed. In patients without LSS, we observe the sedimentation of lumbar nerve roots to the dorsal part of the dural sac on supine magnetic resonance image scans. In patients with symptomatic and morphologic central LSS, this sedimentation is rarely seen. We named this phenomenon "sedimentation sign" and defined the absence of sedimenting nerve roots as positive sedimentation sign for the diagnosis of LSS.This study included 200 patients. Patients in the LSS group (n = 100) showed claudication with or without LBP and leg pain, a cross-sectional area80 mm, and a walking distance200 m; patients in the LBP group (n = 100) had LBP, no leg pain, no claudication, a cross-sectional area of the dural sac120 mm, and a walking distance1000 m. The frequency of a positive sedimentation sign was compared between the 2 groups, and intraobserver and interobserver reliability were assessed in a random subsample (n = 20).A positive sedimentation sign was identified in 94 patients in the LSS group (94%; 95% confidence interval, 90%-99%) but none in the LBP group (0%; 95% confidence interval, 0%-4%). Reliability was kappa = 1.0 (intraobserver) and kappa = 0.93 (interobserver), respectively. There was no difference in the detection of the sign between segmental levels L1-L5 in the LSS group.A positive sedimentation sign exclusively and reliably occurs in patients with LSS, suggesting its usefulness in clinical practice. Future accuracy studies will address its sensitivity and specificity. If they confirm the sign's high specificity, a positive sedimentation sign can rule in LSS, and, with a high sensitivity, a negative sedimentation sign can rule out LSS.

Study design Motion analysis on video files that captured grip and release cycles with fingers. Objective To reveal the kinematic characteristics of finger motion in cervical myelopathy. Summary of background data Myelopathy patients are often unable to smoothly move their fingers in grip and release cycles. Although paradoxical wrist motion (trick motion) and lack of finger coordination are well-known phenomena in myelopathy patients, it is not known which types of myelopathy patients present with these kinematic characteristics, and it is not known why they occur. Methods Thirty patients with myelopathy were evaluated before and after decompressive surgery and compared with 42 healthy controls. The subjects were asked to grip and release with their fingers as rapidly as possible for 15 seconds. Movies taken with a digital camera were divided into 3 animation files of 5-seconds each. Three physicians independently counted the number of finger grip and release cycles of those files in a blinded manner; they also evaluated trick motion of the wrist and lack of finger coordination. Results Both the frequency of trick motion and that of uncoordinated finger motion were significantly higher in the preoperative myelopathy group than in the control group (trick motion, 11.7% vs. 4.8% and uncoordinated finger motion, 15.6% vs. 7.1%), but were the same in the pre- and postoperative myelopathy groups. In the preoperative myelopathy group, the number of grip and release cycles of uncoordinated finger motion files, especially ulnar delay type, was significantly smaller than that of coordinated finger motion files, which meant uncoordinated finger motion was related to the severity of myelopathy. Conclusion Both uncoordinated finger motion and trick motion of the wrist were more frequent in myelopathy patients than in healthy controls, and uncoordinated finger motion was associated with severity of myelopathy, whereas trick motion was not associated with either severity of myelopathy or level of cord compression. These findings contradict the conventional idea that trick motion is associated with the severity of myelopathy.

STUDY DESIGN Controlled, interventional, animal study. OBJECTIVE To observe the reaction of glial cells and endoneurial macrophages in the dorsal root ganglion (DRG) after application of nucleus pulposus (NP) and investigate whether activated DRG glial cells play a role in the pathogenesis of neuropathic pain. SUMMARY OF BACKGROUND DATA Peripheral nerve injury activated DRG and spinal cord glial cells and several cytokines and neurotrophins released from these activated glial cells might induce pain hypersensitivity. METHODS Adult male Sprague-Dawley rats were used. NP harvested from the tail was applied to the left L5 DRG. Behavioral testing was performed to investigate the mechanical withdrawal threshold. The numbers of activated satellite glial cells and endoneurial macrophages were counted, and the expressions of tumor necrosis factor-alpha (TNF-alpha) and glial cell-line derived neurotrophic factor (GDNF) were examined by double-labeled immunohistochemistry and immunoblotting. RESULTS The mechanical withdrawal threshold was significantly decreased for 28 days and then gradually recovered (P < 0.05). Long-term activation of endoneurial macrophages and satellite glial cells in the DRG was observed, and the reactions of these cells correlated well with pain-related behavior. TNF-alpha was expressed in both endoneurial macrophages and activated satellite glial cells, and TNF-alpha expression was significantly increased in the early stage (P < 0.05). Activated satellite glial cells also expressed GDNF, and its expression was significantly increased and persisted for 28 days (P < 0.05). CONCLUSION Activation of DRG glial cells and endoneurial macrophages plays an important role in the pathogenesis of the neuropathic pain state. TNF-alpha actively released from activated glial cells and endoneurial macrophages in the DRG might initiate and maintain the neuropathic pain together with TNF-alpha derived from the applied NP. In the recovery phase, persistent expression of GDNF from activated satellite glial cells might play an important role to restore the function of damaged neurons and recover from neuropathic pain.

Study design Four cases of computed tomography and magnetic resonance imaging documented lumbar nerve root compression associated with a vacuum disc communicating with the epidural space are presented. Objective To give an insight into the mechanism of nerve root compression associated with vacuum disc phenomenon. Summary of background data Few cases of lumbar radiculopathy resulting from epidural gas have been reported and illustrated using cross-sectional imaging studies. Methods The medical records, imaging examinations, and surgical findings (when available) of 4 symptomatic patients with epidural and intradiscal gas collections were reviewed. Three patients underwent surgery with needle aspiration of the epidural gas, and 1 patient was treated conservatively. Results Clinical symptoms of epidural gas cyst were similar to those of other more common causes of nerve root compression. Computed tomography and magnetic resonance imaging findings showed intraspinal gas collection associated with a vacuum disc. One patient had an additional vertebral pneumatocyst. Although evacuation of intraspinal gas resulted in complete cure or major neurologic improvement in 3 patients, an initial period of observation is warranted because gas may disappear spontaneously as in 1 of our patients. All 4 patients recovered full motor and sensory functions of the lower extremities. One year later, patients were completely free of symptoms. Conclusion Although the vacuum disc is considered a common imaging finding of no or not much pathologic significance, occasionally intradiscal gas may leak into the spinal canal. Detection of an epidural gaseous collection at the same level with a vacuum disc strongly suggests a communication between the intervertebral disc and the epidural space. Epidural gas collections can be implicated as a possible cause of radicular symptoms and should be considered in the differential diagnosis of lumbar radiculopathy.

Study Design. Prospective study evaluating the oblique lumbar magnetic resonance imaging (MRI). Objective. To present the technique of oblique lumbar MRI and assess the clinical efficacy of this technique for diagnosis of extraforaminal disc herniation. Summary of Background Data. Herniated lumbar discs are traditionally diagnosed using conventional lumbar axial and sagittal MRI. However, conventional lumbar MRI might not reveal nerve root compression in the extraforaminal area. Oblique lumbar MRI can provide clear visualization of the dorsal root ganglion and lumbar nerve root in the foraminal and extraforaminal areas. Methods. Ten patients diagnosed with extraforaminal disc herniations underwent bilateral oblique lumbar MRIs before surgery (turbo spin-echo T2-weighted sequence). We compared the side with symptomatic extraforaminal disc herniation to the asymptomatic contralateral side. Results. Oblique lumbar MRI succeeded in depicting pedicles, dorsal root ganglions, and lumbar nerve roots of the foraminal and extraforaminal areas. In 9 of 10 patients (90.0%), nerve root compression by the herniated disc in the extraforaminal area was clearly demonstrated when compared with the asymptomatic contralateral side (P < 0.05). In 1 patient with scoliosis and spinal stenosis, oblique MRI could not clearly display foraminal or extraforaminal anatomy due to spinal deformity. Conclusion. In light of this data, we suggest that oblique lumbar MRI can precisely demonstrate nerve roots in foraminal and extraforaminal areas. This technique is a simple and useful diagnostic tool for extraforaminal lumbar disc herniations.

STUDY DESIGN: Report of a traumatic posterior lumbosacral spondyloptosis in a 6-year-old. OBJECTIVES: To describe this type of fracture-dislocation in children. To evaluate a possible trauma mechanism. To evaluate specific characteristics of this type of lesion in children. SUMMARY OF BACKGROUND DATA: Fractures of the lumbar spine in children are rare. They are without exception caused by high-energy trauma. Fracture-dislocations mostly occur in the anterior direction. There are several reports of traumatic retrolisthesis in adults. To our knowledge, this is the first report of a retrolisthesis at the lumbosacral junction in a child. METHODS: While sitting, a 6-year-old boy was hit by a truck. He presented with a flaccid paraparesis below L3. Radiologic investigations showed a posterior spondyloptosis at L5-S1. He was treated by open reduction with a pediatric posterior spinal instrumentation and posterolateral grafting. RESULTS: After 1 year, the patient showed good radiologic fracture reduction and graft incorporation. There was no pain in the lumbar area. There was still a complete neurologic deficit beneath the L3 level, with loss of bladder and anal sphincter function. The patient was entered into a children's rehabilitation program 5 weeks after surgery and is continuously improving his overall functional level. CONCLUSION: Traumatic retrolisthesis of the lumbosacral spine is extremely rare, especially in children. We believe shear force while sitting is the key traumatic factor. We believe a simple posterior fusion with posterolateral grafting is sufficient to stabilize the spine in children. Extensive soft tissue damage causes an elevated risk of infection. Because of root avulsion, the level of paralysis can be several levels higher than the level of dislocation. Language: en

Study design Diagnostic study. Objective To assess the construct validity of the flip test as a sign of nerve root tension. Summary of background data The flip test is commonly performed in patients with sciatica to confirm or otherwise nerve root tension evidenced by a restricted supine straight leg raise (SLR). Passive extension of the knee with the patient in the erect position and the hip flexed is reported to cause a sudden falling or flipping back of the trunk. Although widely known there are no research articles validating this test. Methods Sixty-seven patients with sciatica and magnetic resonance imaging scans confirming disc protrusion and nerve root compression underwent the flip test. The response of the patient was recorded, compared with the supine SLR, and subjected to statistical analysis. Results Thirty-three percent of patients felt no pain, 39% felt pain on full extension of the knee, and 28% resisted full extension of the knee due to pain. Only one-third of patients demonstrated a "flip." The response was related to the supine SLR, such that patients with high SLRs tended not to show a painful reaction whereas all patients with a supine SLR below 45 degrees showed a painful response. Conclusion We consider that the flip test has been substantially misinterpreted in the past. However, it remains a useful check of nerve root tension but only for patients with supine SLRs below 45 degrees . The most reliable response was not a flip but the demonstration of pain on extension of the knee. We would recommend the term "sitting SLR test," as a more accurate and less misleading name.

STUDY DESIGN This is an animal experiment using transcranial motor evoked potentials (TcMEP), mechanically elicited electromyography (EMG), and evoked EMG during spinal nerve root retraction in a pig model. OBJECTIVE To compare the sensitivity of these 3 electrophysiological measures for a constant retraction force applied to an isolated lumbar nerve root for a specific duration of time. SUMMARY OF BACKGROUND DATA The incidence of nerve root injury during lumbar spine surgery ranges from 0.2% to 31%. Direct retraction of spinal nerve roots may cause these injuries, but the amount and duration of force that may safely be applied is not clear. Using an established porcine model, we examined the changes occurring to multimyotomal TcMEPs, mechanically elicited EMGs, and evoked EMGs during continuous retraction of a nerve root at a constant force applied over 10 minutes. METHODS TcMEP, mechanically elicited EMG, and evoked EMG responses were recorded from the tibialis anterior (TA) muscle in 10 experiments. The dominant root innervating the TA was determined with evoked EMG; preretraction TcMEP and nerve root stimulation threshold (NRT) was obtained. The dominant root was retracted at 2 Newton (N) for 10 minutes. TcMEP trials were elicited every minute during retraction. NRT was measured immediately after retraction. TcMEP and NRT were measured after 10 minutes of recovery. RESULTS.: During the 10 minutes of retraction at 2 N, the amplitude of the TA muscle progressively decreased in all trials in a highly significant curvilinear fashion. The mean TcMEP amplitude decreased 59% +/- 14% from baseline values. The mean NRT after 10 minutes of retraction at 2 N rose to 1.8 +/- 0.7 mA (P < 0.01 vs. baseline). The NRT increase after retraction strongly correlated with the decrease in motor evoked potentials amplitude in the TA (R = 0.90, P < 0.001). EMG activity was variable; tonic EMG was observed in only 2 nerve roots (20%). CONCLUSION Three electrophysiologic methods were used intraoperatively to assess neural function during retraction of a single nerve root. Retraction produced consistent changes in TcMEPs and evoked EMG. These 2 methods show promise for assessing the limits on the force and duration of nerve root retraction during spine surgery. Mechanically elicited EMG was not sensitive to the amount and duration of nerve root retraction.

Study design A morphometric analysis, using magnetic resonance imaging (MRI) studies of the lumbar spine. Objective To identify the anatomic position of the ventral root and the retroperitoneal vessels in relation to the vertebral body in normally aligned and deformed spines. Summary of background data The lateral approach to the lumbar spine is a relatively new method for performing interbody fusions. In contrast to the standard open anterior approach with direct vision of the operative field, the lateral approach uses expandable retractors that are positioned under fluoroscopic guidance. Risks of this technique include injury to the exiting nerve root and retroperitoneal vessels. Methods One hundred lumbar spine MRI studies were reviewed from patients treated for various spinal pathologies. The measured intervertebral segments were divided into 3 groups: group 1 (n = 247), normally aligned vertebrae and disc spaces; group 2 (n = 18), degenerative spondylolisthetic segments; and group 3 (n = 19), segments from the apex of degenerative lumbar scoliosis. Axial MR images were used to measure: the vertebral endplate anterior-posterior (AP) diameter, the overlap between the ventral root and the posterior margin of the vertebra, and the overlap between the retroperitoneal large vessels and the anterior edge of the vertebra. Results The overlap between the adjacent neuro-vascular structures and the vertebral body endplate gradually increased from L1-L2 to L4-L5. The maximal overlap, at the L4-L5 level reached 87% resulting in a relatively narrow corridor for performing the operative procedure. Alteration in the anatomic location of the nerve root and the retroperitoneal vessels, in Group 3 (scoliosis) further decreased the safe corridor. Conclusion The safe corridor for performing the discectomy and inserting the intervertebral cage narrows from L1-L2 to the L4-L5 level. This corridor is further narrowed with rotatory deformity of the spine. Using the preoperative MRI to assess the relative position of the adjacent neuro-vascular structures in relation to the lower vertebra's endplate at each level is recommended.

Study design A retrospective study of a new classification and surgical approach of cervical dumbbell tumors. Objective To evaluate PUTH classification. Summary of background data The high recurrence rate and postoperative deformity are unsolved problems. Asazuma's landmark classification could not cover all cases and could not provide clear suggestion for the surgical approach. The ideal classification should be comprehensive, easily understood and of practical value. Methods PUTH classification for cervical dumbbell tumors includes 7 categories (types 1-7) and 2 foraminal modifiers. Posterior approach is appropriate for type 1, 2 and 5 tumors, anterior and anterolateral approach is an ideal choice for type 4 and 6 tumors. Type 7 tumors need combined anterior and posterior approach. Results Forty-four consecutive patients with cervical dumbbell tumor were surgically treated. The pathology included schwannoma in 31 cases, neurofibroma in 9 and ganglioneuroma in 4. Based on PUTH classification, type 3 was diagnosed in 13 cases, type 5 in 17, type 6 in 8, and type 7 in 6. Tumors were unilateral in 41 cases, and bilateral in 3 cases. Five were tumor revision cases. Thirty patients underwent posterior approach, 7 had anterior approach, 1 had anterolateral approach, and 6 had combined approach. Gross total resection was achieved in all the patients. Tumors involved nerve roots were transected in 12 cases. Single vertebral artery was ligated in 3. The complications included cerebrospinal fluid leakage in 18 cases, esophagus injury in 1, Horner syndrome in 1, dysphagia in 2, dyspnea in 1 and deep infection in 1. Thirty-six cases (81.1%) had an average 61-month follow-up. Recurrence was found in only one case (2.8%). Conclusion PUTH classification covers all tumor types and is easier to remember. It is practical and useful for determining the surgical approach. The recurrence rate decreases significantly after radial tumor resection. Revision surgeries are associated with more complications.

Study Design. DNA array analysis of dorsal root ganglion (DRG) using a rat model with nerve root constriction. Objective. To determine the molecular changes in the DRG adjacent to the injured nerve root in a lumbar radiculopathy model. Summary of Background Data. DNA array analysis in lumbar radiculopathy model has so far focused on the spinal dorsal horn. The molecular changes in the DRG adjacent to the injured nerve root in lumbar radiculopathy remain to be determined. Methods. Bilateral L5 DRGs were removed from 12 Sprague-Dawley rats on days 2, 7, 14, and 21 after nerve root ligation and on day 7 from 3 rats with sham operation. The aRNAs from the DRGs with nerve root ligation were labeled with Cy5 dye and those from the opposite side DRG (control) were labeled with Cy3 dye, and then hybridized to a 7793-spot Panorama Micro Array. It was considered to be significantly upregulated, when an average expression ratio of Cy5 to Cy3 was 2 or more. Genes upregulated were classified into early phase group (upregulated on day 2), midphase group (upregulated on days 7 and 14), and continuous group (upregulated from day 2 to 21). Seventeen genes were subjected to validation analysis with real-time quantitative PCR. Results. There were 16 upregulated genes in the early phase group, 56 genes in the midphase group, and 17 genes in the continuous group. Functional categorization revealed dominantly upregulated gene categories in each group; transcription/translation in the early phase group, enzyme/metabolism in the midphase group, and structure in the continuous group. Validation analysis of 17 genes demonstrated mean relative expression of 2.0 or more in all but 1 gene in the DRGs with nerve root ligation and none of them in the DRGs with sham operation. Conclusion. The genes identified in this study, especially those involved in pain signaling and inflammation, serve as potential targets for molecular-based therapy for lumbar radiculopathy.

STUDY DESIGN Retrospective review of all patients with intact spinal cords, who had posterior spinal fusion (PSF) to the pelvis with Dunn-McCarthy instrumentation. Inclusion criteria were communicative patients with Dunn-McCarthy instrumentation, functioning spinal cords, and sensate lower extremities. We excluded patients with myelomeningocele or spinal cord injury because they are physiologically unable to develop neuropathic lower extremity pain. We distinguished neuropathic lower extremity pain from positional discomfort by eliminating patients whose symptoms resolved in the first postoperative month and patients whose pain persisted greater than a month but did not require treatment or further investigation. OBJECTIVE To determine the incidence and clinical course of neuropathic lower extremity pain following PSF with Dunn-McCarthy instrumentation. SUMMARY OF BACKGROUND DATA The Dunn-McCarthy technique for instrumented PSF to the pelvis places a rod in close proximity to the L5 nerve root and anterior neurovascular structures. We have treated several patients who developed neuropathic lower extremity pain following PSF with Dunn-McCarthy instrumentation. RESULTS Seven of 49 patients developed neuropathic pain in a lower extremity after PSF to the pelvis with Dunn-McCarthy instrumentation. Six patients were managed with Neurontin, and 1, with Valium. Two patients were offered removal of their implants, but their symptoms resolved before resection was performed. CONCLUSION Pelvic fixation with Dunn-McCarthy instrumentation was associated with a 14% incidence of severe, unilateral neuropathic lower extremity pain.

STUDY DESIGN Retrospective analysis of magnetic resonance imaging (MRI) and clinical findings about chemical radiculitis-associated anular tear in patients with radiculopathy. OBJECTIVE To investigate MRI findings of the chemical radiculitis caused by anular tears and to determine whether chemical radiculitis detected by MRI is the cause of radiculopathy. SUMMARY OF BACKGROUND DATA Many studies document that irritation of adjacent nerve roots by a chemical mediator of inflammation from the nucleus pulposus may result in radiculopathy. Computed tomography (CT) discography may be the best examination for diagnosing discogenic chemical radiculitis but is too invasive. A reliable imaging method for replacing invasive provocative CT discography and diagnosing chemical radiculitis is required. METHODS The study population consisted of 12 patients with pain referred to leg(s) with or without low back pain who underwent lumbar spine MRI. All cases of our study demonstrated perianular enhancement caused by chemical radiculitis associated with anular tears. Patterns and locations of perianular enhancement adjacent to anular tears on MRI were assessed. MRI findings were compared with clinical symptoms and/or provocative transforaminal epidural injection (n = 6). For documentation of the relationship between perianular enhancement and radiculopathy, provocative CT discography was performed in 2 cases. RESULTS Perianular enhancement associated with anular tears revealed thick linear patterns (2.5-7 mm thickness) along margins of anular tears on contrast enhanced axial T1-weighted images with fat suppression. Locations of perianular enhancement adjacent to anular tears were at foraminal (n = 6) and extraforaminal portions (n = 6). CT discography showed a leak of contrast from anular tear to the perianular regions. Pain reproduction at contrast leak level during discography showed concordant pain. There was an apparent correlation between perianular enhancement on MRI and clinical symptoms or provocative epidural nerve root injection in all cases. CONCLUSION The perianular enhancement adjacent to anular tears on MRI may be relevant in the diagnosis of symptomatic chemical radiculitis.

The role of 5-hydroxytryptamine (5-HT) in sciatica in lumbar disc herniation (LDH) in rats was investigated.We evaluated the effects of exogenous 5-HT applied on the nerve root on pain-related behavior, the release of endogenous 5-HT in plasma, and the expression of 5-HT2A receptors in dorsal root ganglion (DRG) in a rat LDH model.In previous studies, 5-HT2A receptor antagonists improved sciatica in patients with LDH and attenuated pain-related behavior induced by nucleus pulposus applied to the nerve root in rats.Adult female Sprague-Dawley rats were divided into four experimental groups [control group; low-dose (10 microg) 5-HT-group; high-dose (30 microg) 5-HT-group; and autologous nucleus pulposus (NP) and saline group] and each drug was applied to the L5 nerve root. Von Frey tests were used for pain-behavior testing. To assess levels of endogenous 5-HT released in capillaries surrounding inflamed nerve roots, we measured 5-hydroxyindole acetic acid (5-HIAA), a metabolite of 5-HT. Expression of 5-HT2A receptors in the left L5 DRG was examined by immunohistochemical and immunoblotting analyses in the control and NP groups.Mechanical withdrawal thresholds of the high-dose 5-HT and the NP groups were significantly decreased after surgery compared with the control group and recovered after 14 days in the high-dose 5-HT group. 5-HIAA in plasma was increased by nucleus pulposus applied on the nerve root for 7 days after surgery. The expression of 5-HT2A receptors was enhanced in a time-dependent manner by nucleus pulposus.Exogenous 5-HT to the nerve root induced pain-related behavior with short-lasting effects compared with the nucleus pulposus application. 5-HIAA content in plasma and expression of 5-HT2A receptors in DRG neurons increased early time points after the nucleus pulposus application. These results suggest that 5-HT plays a role in the early phase of the chemical pathogenesis of sciatica in LDH in rats.

STUDY DESIGN An anatomic study in which the lumbar plexuses of 14 embalmed cadavers were dissected bilaterally and measured using a posterior approach. OBJECTIVE To determine the cephalocaudal (root-to-root) distances and the mediolateral (root-to-tether) distances within the lumbar plexus and determine the feasibility for removal of a lumbar total disc replacement (TDR) through these anatomic spaces using a posterior approach. SUMMARY OF BACKGROUND DATA Currently, lumbar TDRs are implanted primarily through an anterior retroperitoneal or transperitoneal approach. However, revision surgeries through these approaches can be complicated by significant adhesions, with potential injuries to intra- and retroperitoneal contents. Advancements in accessing anterior column structures through a posterior lumbar extracavitary approach suggest that posterior removal of TDRs may be an alternative. Unlike the thoracic extracavitary approach in which ligation of the thoracic nerve rarely leaves significant morbidity, the lumbar extracavitary approach cannot rely on the analogous ligation of the lumbar root to achieve access. Therefore, feasibility of the lumbar extracavitary approach depends on the presence of sufficient anatomic space between the tethered nerves of the lumbar plexus. METHODS Fourteen adult cadavers (5 M/9F) were dissected through a posterior approach to expose the lumbar plexus bilaterally. The root-to-root distances at levels L2-S1 and corresponding root-to-tether distances at levels L3-L5 were measured bilaterally. RESULTS Root-to-root distance was smallest at the male L5-S1 interval (11.7 +/- standard deviations 4.1 mm). Root-to-tether distance was smallest at the female L5 (43.1 +/- standard deviations 8.4 mm). These plexus measurements compare favorably with the CHARITE TDR components, in which the thickest sliding core is 11.0 mm in height and the largest endplate is 42.0 mm in width. CONCLUSION This anatomic study suggests that posterior TDR removal is possible in the lumbar spine without undue risk to the surrounding nervous structures.