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Purpose: Simpson grade II removal (coagulation of the dural attachment after gross total removal) of spinal meningioma is considered an acceptable alternative, but increased recurrence after more than 10 years has been reported. More attention must be paid to the long-term surgical outcomes after Simpson grade II removal., Methods: A retrospective review was performed for 20 patients (M:F = 5:15; age, 59 ± 9 years) with Simpson grade II removal (mean follow-up period, 12.9 years; range 10.0-17.5). Magnetic resonance (MR) imaging was conducted in 17 patients at 88 ± 52 months (range 12-157). During the same period, Simpson grade I removal (removal of the dural origin) was performed in 21 patients (follow-up, 89 ± 87 months; range 9-316). Radiological recurrence was defined as a visible tumor on a follow-up MR image, and clinical tumor recurrence was defined as the recurrence of symptoms., Results: At the final follow-up, neurological symptoms had improved in 16/20 patients and remained stable in 4/20. A recurrent tumor was detected in one patient due to increased back pain at 92 months postoperative, but the symptom was stable without surgery until the last follow-up (124 months). The radiological and clinical recurrence-free survival periods were 150 ± 7 months (95 % CI 136-163) and 204 ± 6 months (95 % CI 193-215), respectively. There was no recurrence after Simpson grade I removal, whereas neurological deterioration occurred in two patients after surgery., Conclusions: Simpson grade II removal may be an alternative option if the risk of complications with Simpson grade I removal is expected to be high.

Surgical treatment is indicated in patients with moderate to severe myelopathy from cervical ossification of the posterior longitudinal ligaments (OPLL), but undertaking prophylactic surgery for asymptomatic or mildly symptomatic patients with a severely compressed spinal cord is debatable. Patients with <8mm space available in the spinal canal on CT scan, were divided into groups I (mild symptoms, Japanese Orthopedic Association (JOA) score range 15-16) and II (moderate to severe symptoms, JOA score <14). Medical charts including operative records were reviewed to obtain preoperative, perioperative, and final postoperative follow-up data. Group I included 24 patients (20 men, mean age 52.42years), and Group II included 46 patients (33 men, mean age 54.67years). Compared to Group II, Group I had a shorter preoperative symptom duration (19.21 vs. 38.23months, p=0.046) and a more favorable JOA score at final follow-up (p=0.007). The mean numbers of OPLL-involved segments were similar (Group I 2.96, Group II 3.09; p=0.773) as were the mean numbers of operated segments (Group I 2.71, Group II 3.35; p=0.076). Perioperative blood loss, operation duration, and hospital stay duration were significantly more favorable in Group I than in Group II. The numbers of surgery-related complications in the two groups were similar. Early surgical treatment for a favorable neurologic recovery with a low perioperative risk can be recommended in patients with severely compressed spinal cord from cervical OPLL who present with mild arm numbness. Surgery-related complications, however, should be carefully monitored regardless of symptom severity., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Study Design: A biomechanical comparison among the intact C2 to C7 segments, the C5 to C6 segments implanted with fusion cage, and three different artificial disc replacements (ADRs) by finite element (FE) model creation reflecting the entire cervical spine below C2., Objective: The aim of this study was to analyze the biomechanical changes in subaxial cervical spine after ADR and to verify the efficacy of a new mobile core artificial disc Baguera C that is designed to absorb shock., Summary of Background Data: Scarce references could be found and compared regarding the cervical ADR devices' biomechanical differences that are consequently related to their different clinical results., Methods: One fusion device (CJ cage system, WINNOVA) and three different cervical artificial discs (Prodisc-C Nova (DePuy Synthes), Discocerv (Scient'x/Alphatec), Baguera C (Spineart)) were inserted at C5-6 disc space inside the FE model and analyzed. Hybrid loading conditions, under bending moments of 1 Nm along flexion, extension, lateral bending, and axial rotation with a compressive force of 50 N along the follower loading direction, were used in this study. Biomechanical behaviors such as segmental mobility, facet joint forces, and possible wear debris phenomenon inside the core were investigated., Results: The segmental motions as well as facet joint forces were exaggerated after ADR regardless of type of the devices. The Baguera C mimicked the intact cervical spine regarding the location of the center of rotation only during the flexion moment. It also showed a relatively wider distribution of the contact area and significantly lower contact pressure distribution on the core than the other two devices. A "lift off" phenomenon was noted for other two devices according to the specific loading condition., Conclusion: The mobile core artificial disc Baguera C can be considered biomechanically superior to other devices by demonstrating no "lift off" phenomenon, and significantly lower contact pressure distribution on core., Level of Evidence: N/A.

Objective: The complex structure around the upper cervical spine makes surgical treatment difficult. the present study aimed to analyze how patients with ossification of the longitudinal ligament (OPLL) involving the C2 were managed and to compare the surgical outcomes according to the C2 involvement., Methods: Ninety-five patients with cervical OPLL who underwent surgical treatment were divided into C2 involvement (C2+ group, 40 patients) or none (C2- group, 55 patients). In the C2+ group, subanalysis was conducted to according to the C2 surgery (C2 surgery+ group, 14 patients)., Results: All patients had a minimum of 1 year of follow-up with a mean of 51.36 months. The most common location of the narrowest space available for the spinal cord was C2 and C5 in the C2+ and C2- groups, respectively. In the C2+ group, a longer OPLL with thickened diameter was radiographically demonstrated, but clinical outcomes were not different from the C2- group. In the C2 surgery+ group, the narrowest spinal cord was common in the C2 (50.0%), and an extension of the signal change of spinal cord to the C2 was observed in 4 patients, showing a statistical difference. C2 surgery was performed in all patients using the posterior approach and it did not result in different clinical outcomes or surgery-related complications. An anterior surgical approach was deemed risky given the chance of the development of complications., Conclusions: Both of C2 involvement from OPLL and surgery including the C2 did not affect clinical outcomes. The posterior decompressive surgery is safer and more effective than the anterior approach regarding the development of surgery-related complications., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Background: Despite the firmly established occupational risk of exposure to X-rays, they are used extensively in spine surgeries. Shielding by lead aprons is the most common protective practice. We quantified the level of their radiation blocking ability in a real-life setting., Methods: Single-center, prospective, randomized study of adult patients with degenerative lumbar disorders, scheduled to undergo posterior lumbar interbody fusion. Instrumentation was performed in either a robot-assisted, minimally invasive approach (RO) or a conventional, fluoroscopically-assisted, open approach (FA). Outcome measures included the quantitative measurement of the surgeon's actual exposure to radiation, as recorded by thermo-luminescent dosimeters (TLD) worn both above and under the 0.5 mm thyroid and trunk lead protectors., Findings: Sixty four patients were included in this study, 34 in the RO cohort and 30 in the FA cohort. The radiation blocked by the aprons, represented as the ratio of the under-apron to above-apron TLDs, averaged 37.1% (range 25.4-48.3%, 95% confidence interval between 30.6-43.6%). In the RO cohort, the average per-screw radiation dose and time were 51.9% and 73.7% lower, respectively, than the per screw exposure in the FA cohort., Interpretation: The 0.5 mm lead aprons blocked just over one third of the radiation scattered towards the surgeon. Use of robotic-guidance in a minimally invasive approach provided for a reduction of 62.5% of the overall radiation the surgeon was exposed to during open conventional approach. We conclude that reduced radiation use (e.g. by using robotic guidance) is a more effective strategy for minimizing exposure to radiation than reliance on protection by lead aprons, and recommend utilization of practices and technologies that reduce the surgical team's routine exposure to X-rays.

Study Design A multinational, multiethnic, cross-sectional image-based study was performed in 33 institutions, representing 10 countries, which were part of the AOSpine Asia Pacific Research Collaboration Consortium. Objective Lumbar facet joint orientation has been reported to be associated with the development of degenerative spondylolisthesis (DS). The role of ethnicity regarding facet joint orientation remains uncertain. As such, the following study was performed across a wide-ranging population base to assess the role of ethnicity in facet joint orientation in patients with DS in the Asia Pacific region. Methods Lateral standing X-rays and axial magnetic resonance imaging scans were obtained for patients with lumbar DS. The DS parameters and facet joint angulations were assessed from L3-S1. Sex, age, body mass index (BMI), and ethnicity were also noted. Results The study included 371 patients with known ethnic origin (mean age: 62.0 years; 64% males, 36% females). The mean BMI was 25.6 kg/m(2). The level of DS was most prevalent at L4-L5 (74.7%). There were 28.8% Indian, 28.6% Japanese, 18.1% Chinese, 8.6% Korean, 6.5% Thai, 4.9% Caucasian, 2.7% Filipino, and 1.9% Malay patients. Variations in facet joint angulations were noted from L3 to S1 and between patients with and without DS (p < 0.05). No differences were noted with regards to sex and overall BMI to facet joint angulations (p > 0.05); however, increasing age was found to increase the degree of angulation throughout the lumbar spine (p < 0.05). Accounting for age and the presence or absence of DS at each level, no statistically significant differences between ethnicity and degree of facet joint angulations from L3-L5 were noted (p > 0.05). Ethnic variations were noted in non-DS L5-S1 facet joint angulations, predominantly between Caucasian, Chinese, and Indian ethnicities (p < 0.05). Conclusions This study is the first to suggest that ethnicity may not play a role in facet joint orientation in the majority of cases of DS in the Asia-Pacific region. Findings from this study may facilitate future comparative studies in other multiethnic populations. An understanding of ethnic variability may assist in identifying those patients at risk of postsurgical development or progression of DS. This study also serves as a model for large-scale multicenter studies across different ethnic groups and cultural boundaries in Asia.

Objective: Comparing different surgical approaches for spinal schwannoma, the safety and efficacy of the minimally invasive surgery (MIS) approach were demonstrated, and a suitable indication for each surgical approach was analyzed., Methods: This study comprised 49 consecutive patients with intradural extramedullary schwannoma who underwent surgical resection: 31 patients via MIS approach (MIS group; 6 patients via a muscle-splitting approach using a tubular retractor and 25 patients via unilateral hemilaminectomy preserving the contralateral paraspinal muscle) and 18 patients via total laminectomy (TL group). Medical records including perioperative data and radiologic data were reviewed., Results: On initial magnetic resonance imaging, the mean maximal sagittal diameter of the tumor was 23.9 mm in the MIS group and 26.9 mm in the TL group, and the mean maximal axial diameter was 16.1 mm in the MIS group and 22.8 mm in the TL group (P = 0.452 and P = 0.011, respectively). The foraminal extension of tumor was identified in 8 patients in the MIS group and 9 patients in the TL group (P = 0.081). The tumor location was the lumbar spine in 20 patients in the MIS group and the cervicothoracic spine in 17 patients in the TL group (P = 0.001). Intraoperatively, all tumors in the MIS group could be totally resected with reduced operative time and blood loss. During the follow-up period of 38.2 months in the MIS group and 51.2 months in the TL group, the clinical improvement was not different between the surgical approaches (P = 0.332)., Conclusions: Safe and complete resection of intradural extramedullary schwannoma was obtained through the MIS approach. Regardless of sagittal extension of the tumor, a schwannoma with an axial diameter of 16 mm located in the lumbar spine can be effectively treated with the MIS approach, including foraminal extension., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Purpose: To evaluate the incidence and risk factors for adjacent segment pathology (ASP) after anterior cervical spinal surgery., Methods: Fourteen patients (12 male, mean age 47.1 years) who underwent single-level cervical disk arthroplasty (CDA group) and 28 case-matched patients (24 male, mean age 53.6 years) who underwent single-level anterior cervical discectomy and fusion (ACDF group) were included. Presence of radiologic ASP (RASP) was based on observed changes in anterior osteophytes, disks, and calcification of the anterior longitudinal ligament on lateral radiographs., Results: The mean follow-up period was 43.4 months in the CDA group and 44.6 months in the ACDF group. At final follow-up, ASP was observed in 5 (35.7%) CDA patients and 16 (57.1%) ACDF patients (p = 0.272). The interval between surgery and ASP development was 33.8 months in the CDA group and 16.3 months in the ACDF group (p = 0.046). The ASP risk factor analysis indicated postoperative cervical angle at C3-7 being more lordotic in non-ASP patients in both groups. Restoration of lordosis occurred in the CDA group regardless of the presence of ASP, but heterotopic ossification development was associated with the presence of ASP in the CDA group. And the CDA group had significantly greater clinical improvements than those in the ACDF group when ASP was present., Conclusion: In both CDA and ACDF patients, RASP developed, but CDA was associated with a delay in ASP development. A good clinical outcome was expected in CDA group, even when ASP developed. Restoration of cervical lordosis was an important factor in anterior cervical spine surgery.

Purpose: Spinal intradural extramedullary (IDEM) schwannoma diagnosed by magnetic resonance (MR) imaging is sometimes detected incidentally. Because the natural history of spinal IDEM schwannoma has not been established well, questions remain regarding whether small and asymptomatic tumour has to be removed. We aimed to assess the natural history of spinal schwannoma diagnosed by MR imaging using an accurate and reliable method., Methods: All patients who were diagnosed with spinal IDEM schwannoma by MR imaging and did not undergo surgical resection immediately were recruited. A number of 56 tumours were enrolled finally. Tumour volume was measured using the volume quantification method from the baseline through the final follow-up. Receiver operating characteristics plots were used to define cut-off value of discrimination., Results: The probable schwannoma grew 5.45% [median value of volumetric growth rate (VGR); interquartile range 0.14-14.19] annually with a mean surveillance interval of 43.6 months. Of the 56 tumours, some tumours kept growing rapidly and the others did not. The median annual VGR of the growing and stable probable schwannomas was 13.02 and -0.09%, respectively (P<0.001). They can be roughly divided by 2.5% of the annual VGR and usually maintained each growth pattern and the cross-over rate to growth pattern was 15.6%., Conclusions: Spinal probable IDEM schwannoma grew 5.45% of the tumour volume annually and can be divided into growing and stable tumours. The tumour that grows≥2.5% of volume per year needs a careful inspection because it may be not benign schwannoma and keep growing continuously.

This study is to estimate the diagnostic accuracy of Tokuhashi and Tomita scores that assures 6-month predicting survival regarded as a standard of surgical treatment. We searched PubMed, EMBASE, European PubMed central, and the Cochrane library for papers about the sensitivities and specificities of the Tokuhashi and/or Tomita scores to estimate predicting survival. Studies with cut-off values of ≥9 for Tokuhashi and ≤7 for Tomita scores based on prior studies were enrolled. Sensitivity, specificity, diagnostic odds ratio (DOR), area under the curve (AUC), and the best cut-off value were calculated via meta-analysis and individual participant data analysis. Finally, 22 studies were enrolled in the meta-analysis, and 1095 patients from 8 studies were included in the individual data analysis. In the meta-analysis, the pooled sensitivity/specificity/DOR for 6-month survival were 57.7 %/76.6 %/4.70 for the Tokuhashi score and 81.8 %/47.8 %/4.93 for Tomita score. The AUC of summary receiver operating characteristic plots was 0.748 for the Tokuhashi score and 0.714 for the Tomita score. Although Tokuhashi score was more accurate than Tomita score slightly, both showed low accuracy to predict 6 months residual survival. Moreover, the best cut-off values of Tokuhashi and Tomita scores were 8 and 6, not 9 and 7, for predicting 6-month survival, respectively. Estimation of 6-month predicting survival to decide surgery in patients with spinal metastasis is quite limited by using Tokuhashi and Tomita scores alone. Tokuhashi and Tomita scores could be incorporated as part of a multidisciplinary approach or perhaps interpreted in the context of a multidisciplinary approach.

Background: Subsidence is a frequent phenomenon in the interbody fusion process in patients with anterior cervical discectomy and fusion (ACDF). There is little evidence of whether subsidence in the cervical spine has any impact on clinical outcomes., Objectives: The purpose of this study is to investigate the correlation of subsidence and clinical outcomes after ACDF and to consider reasons subsidence might not cause unfavorable clinical outcomes., Methods: A total of 158 consecutive patients who underwent single-level ACDF were included. The patients were divided into a subsidence group (S-group) and a no subsidence group (N-group), with subsidence defined as a decrease by ≥3 mm in total intervertebral height (TIH). We analyzed outcomes resulting from subsidence, particularly focusing on clinical outcomes and subsequent global and segmental kyphosis using a repeated measure analysis of variance (RM-ANOVA)., Results: Subsidence occurred in 74 patients (46.8%) as of a 12-month follow-up. The S-group included 58.6% with a stand-alone cage for interbody fusion (p = 0.002). Clinical outcomes improved significantly over time (neck pain, RM-ANOVA: F(1.3, 205) = 125.1, p < 0.001; arm pain, RM-ANOVA: F(1.3, 203) = 290.8, p < 0.001). There was no significant difference in interaction with subsidence and clinical outcomes between the S- and N-group (neck pain, RM-ANOVA: F(2,153) = 1.04, p = 0.356, partial η(2) = 0.229; arm pain, RM-ANOVA: F(2,153) = 0.56, p = 0.571, partial η(2) = 0.142). Segmental angle increased in both groups over time and showed a statistically significant difference between the S- and N-groups (RM-ANOVA: F(3,143) = 6.148, p = 0.001, partial η(2) = 0.959). Although, global cervical angle decreased generally and displayed no statically significant difference between the S- and N-group (RM-ANOVA: F(3,119) = 2.361, p = 0.075, partial η(2) = 0.056)., Conclusions: Radiographic subsidence after ACDF occurred in 46.8% patients as of 12 months after the single-level ACDF. The lack of correlation between bad clinical outcome and radiographic subsidence may be due to segmental kyphosis, preserved posterior height, and maintaining the global cervical angle.

Study Design Retrospective study. Objective Minor trauma, even from a simple fall, can often cause cervical myelopathy, necessitating surgery in elderly patients who may be unaware of their posterior longitudinal ligament ossification (OPLL). The aim of this study is to determine the influence of trauma on the neurologic course in patients who have undergone surgery for cervical OPLL. Methods Patients who underwent surgery due to OPLL were divided by trauma history and compared (34 in the trauma group; 70 in the nontrauma group). Results Ground falls were the most common type of trauma (20 patients, low-energy injuries), but 23 patients developed new symptoms after a trauma. Although the symptom duration (17.68 months) was shorter, the Japanese Orthopedic Association (JOA) score and the Nurick scale showed lower values in the trauma group. Trauma histories led patients to earlier hospital visits. Initial JOA scores were associated with a good recovery status upon the last follow-up in both the groups. The narrowest diameter of the spinal canal showed different radiologic parameters: 5.78 mm in the trauma group and 6.52 mm in the nontrauma group. Conclusion Minor trauma can cause the unexpected development of new symptoms in patients unaware of cervical OPLL. Patients with a history of trauma had lower initial JOA scores and showed a narrower spinal canal compared with a nontrauma group. The initial JOA scores were correlated with a good recovery status upon the last follow-up.

Though growth factors allow tissue regeneration, the trade-off between their effectiveness and adverse effects limits clinical application. The key issues in current growth factor therapy largely derive from initial burst pharmacokinetics, rapid clearance, and proteolytic cleavage resulting in clinical ineffectiveness and diverse complications. While a number of studies have focused on the development of carriers, issues arising from soluble growth factor remain. In this study, we report a prodrug of growth factors constituting a novel mode of action (MoA). To mimic endogenous protein processing in cells, we developed a recombinant BMP-2 polypeptide based on a protein transduction domain (PTD) to transduce the protein into cells followed by furin-mediated protein cleavage and secretion of active growth factor. As proof of concept, a few micrograms scale of PTD-BMP-2 polypeptide sufficed to induce bone regeneration in vivo. As a simple platform, our technique can easily be extended to delivery of BMP-7 and DKK-1 as therapeutics for TGF-β and canonical Wnt signaling, respectively, to suppress the epithelial-mesenchymal transition (EMT), which constitutes a fundamental biological mechanism of many diseases. This technique largely overcomes the limitations of current soluble growth factors and opens the door to next generation growth factor therapeutics., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Purpose: Traumatic cervical spinal cord injuries (SCIs) frequently develop dural tears and resultant cerebrospinal fluid (CSF) leaks. They are not usually identified with advanced imaging, and there are no reports on managing CSF leaks after cervical trauma. Hence, the authors evaluated the incidence of CSF leaks after cervical SCIs and described how to predict and manage CSF leaks., Methods: An observational retrospective study was done confirming intraoperative CSF leaks among 53 patients with anterior cervical surgery after cervical spine trauma between 2004 and 2011., Results: Seven patients (13.2%) had dural tears and resultant CSF leaks intraoperatively (M:F ratio of 6:1; mean age, 44.7 years). An initial poor American Spinal Injury Association (ASIA) scale was significantly associated with CSF leaks (p = 0.009). From magnetic resonance imaging (MRI), disruption of the ligamentum flavum was correlated with CSF leaks (p = 0.02). Intraoperative application of fibrin glue on the operated site, postoperative management through the early removal of the wound drain within the first 24 h and early rehabilitation were performed in patients with CSF leaks without perioperative insertion of a lumbar drain. During the follow-up period, none of the patients developed CSF-leak-related complications., Conclusion: The incidence of CSF leaks after traumatic cervical SCI is relatively higher than that of degenerative cervical spinal surgery. An initial poor neurological status and disruption of the ligamentum flavum on the MRI in patients were predictable factors of dural tears and CSF leaks.

Spinal cord tumors still challenge clinicians because of their neurological deterioration before and after surgery. Epidermoid cyst is one of the rare intramedullary lesions producing neurological deterioration in cervical spine and it has been reported four times in the literature. We report the case of an intramedullary epidermoid cyst showing a longstanding history of paraplegia as well as recent slowly progressive tingling paresthesia extending from C4 to T10 and weakness in both hands., (Georg Thieme Verlag KG Stuttgart · New York.)

Purpose: There are few researches that demonstrate the relationship between the extent of syringomyelia and sagittal alignment of the cervical spine. The purpose of this study is to investigate the correlation between the change of syrinx size and cervical alignment., Methods: From January 2001 to June 2008, we operated on 207 patients who had syringomyelia. The associated diseases were categorized by Chiari I malformation, tumor, trauma, spinal stenotic lesion, inflammatory disease and idiopathic causes. Thirty patients who had Chiari I malformation associated with syringomyelia and who underwent foramen magnum decompression (FMD), participated in this study. We excluded patients with scoliosis, cervical instrumentation, tumor, trauma, myelomeningocele, hydrocephalus, tethered cord and congenital vertebral anomalies. Lateral radiographs in neutral and magnetic resonance imaging were taken pre- and postoperatively., Results: Mean follow-up was 6.5 ± 1.5 years (ranged from 4.0 to 9.5 years). The mean pre- and postoperative lordosis angles at C2-C7 were -5.9° ± 1.0° and -10.4° ± 1.0°, respectively (P = 0.001). There was significant correlation between the differences of syrinx width and the cervical lordotic angles before and after surgery (P = 0.016). After FMD, syringomyelia and cervical alignment improved in 28 (93.3%) and 25 (85.18%) of 30 patients, respectively. There was significant correlation between recovery rate by Japanese Orthopaedic Association scores and the difference of the cervical lordotic angles before and after surgery (P = 0.022)., Conclusions: The present results demonstrate that the decrease of syrinx size by FMD may restore the cervical lordosis. We suggest that the postoperative cervical alignment might be a predictive factor for neurological outcome.

Background: There have been numerous studies on the outcomes of surgery for spinal cord cavernous angiomas. However, the natural history of conservatively treated disease is not well known. The aim of this retrospective study was to investigate the outcomes of conservatively managed patients with spinal cord cavernous angioma to determine the appropriate treatment strategies., Methods: Twenty-four patients who visited a single institution over an 11-year period and who were treated conservatively were enrolled in this study. Their medical records and radiological images were reviewed retrospectively. The neurologic status of the patients was assessed using the Japanese Orthopedic Association scoring system and the clinical presentation of the patients was classified into the following 4 categories: type A, asymptomatic; B, pain only; C, sensory deficits; and D, sensory and motor deficits. The results of types C and D patients were compared with the results of previously reported surgical series from our institution., Results: The mean age of the enrolled patients was 52.0 years (21-73). The mean duration of the clinical follow-up was 60.5 months (11-119) and the follow-up using magnetic resonance imaging was 52.4 months (3-122). Cavernous angiomas presented in the cervical spinal cord in 12 patients, thoracic spinal cord in 10 patients and in multiple levels of the spinal cord in 2 patients. There were 5, 5, 7, and 7 patients, respectively, classified with types A, B, C, and D for clinical presentations. The rate of recurrent hemorrhage was 1.7 %/patient-year and all recurrent hemorrhages only developed in type C or D patients. In types C and D patients, improvement in the JOA score during the follow-up period was 0.77 ± 1.8 in the conservative group and 1.07 ± 1.8 in the surgical group (p = 0.500). However, improvement in the JOA sensory score after surgical treatment was statistically significant (P = 0.007)., Conclusions: Conservative treatment may be a reasonable treatment strategy for patients with types A and B. If patients present with type C or D, surgical treatment is recommended considering the better improvements in sensory deficits and the high rate of recurrent hemorrhage in such patients.

Background and Importance: Cerebrospinal fluid (CSF) leakage can cause abducens nerve palsy which is such a rare complication after spine surgery., Clinical Presentation: A 48-year-old man was diagnosed with isolated abducens nerve palsy due to CSF leakage by inadvertent dural tearing after lumbar discectomy. We performed primary dural repair of CSF leakage and 1 week after, the diplopia and headache disappeared with complete resolution of CSF leakage. We will also review the clinical features and outcomes of three cases that have been reported in the literature., Conclusion: This rare complication of spinal surgery helped us to discuss appropriate therapeutic strategies for the early surgical management of cranial nerve palsy following CSF leakage.

Purpose: The aims of the present study were to compare the biomechanical effects on the adjacent segments after mono-segmental floating fusion with posterior semi-rigid or rigid stabilization, and to evaluate the effect of the amount of fusion mass on the biomechanical differences., Methods: A detailed, nonlinear L1-S1 finite element model had been developed and validated. Then five models were reconstructed by different fixation techniques on the L3-L4 level: rigid fixation with an interbody spacer (Ti + IS), rigid fixation with a large interbody spacer (Ti + IS&#95;all), semi-rigid fixation with an interbody spacer (PEEK + IS), semi-rigid fixation with a large interbody spacer (PEEK + IS&#95;all), and semi-rigid fixation only (PEEK). Analyses were conducted for the case of erect standing position, flexion, and extension motion., Results: At L1-L2 and L2-L3, PEEK + IS demonstrated less inter-segmental rotation and nucleus pressure increments from the intact model compared with Ti + IS. The L4-L5 and L5-S1 levels showed slightly higher values with PEEK + IS, but these differences among the instrumented models were not significant. The motion difference based on the fusion mass at the adjacent levels was at most 3%. All instrumentation cases generated a 55% higher facet contact force at the lower adjacent level (L4-L5) compared to that of the intact model during 26° extension and the largest increment was detected at the upper adjacent level (L2-L3) in the Ti + IS. Instrumentation with Ti + IS markedly increased the stress in the intervertebral disk at the upper adjacent level, while the stress with PEEK + IS appeared largest at the lower adjacent level., Conclusions: Posterior instrumentation with semi-rigid rods may lower the incidence of disk and facet degeneration in the upper adjacent segment compared to rigid rods. On the other hand, the possibility of facet degeneration will be similar for all instrumentation devices in the lower adjacent segment in the long-term. The stiffness difference between rigid and semi-rigid rods on the changes in the adjacent motion segments was more crucial than amount of fusion mass.

Background: Spinal epidural arachnoid cysts (EAC) are rare and may present with myelopathy, which can be completely curable with surgery. The majority of investigators believe that the repairment of dural defect is important to treat EAC. However, the necessity of excising EACs remains controversial. The purpose of this study was to find a reasonable surgical technique for treatment of EACs after considering the clinical outcome, recurrence, and complications., Methods: The data from 44 operations in the literature and eight cases from our own experience were analyzed. This data included the surgical method, patient characteristics, level and size of the EAC, global assessment of the clinical outcomes, and the incidence of recurrence., Results: The recurrence rate was 2.0 % and 66.7 % in the patients who underwent repair of the dural defect and in those failed to repair of the dural defect, respectively (p = 0.007). The recurrence rate was 8.3 % and 3.6 % in patients who underwent complete EAC excision totally, and those who underwent EAC fenestration only, respectively (p = 0.590). The clinical outcome in patients with repaired dural defects was significantly better than that in patients with unrepaired dural defects (2.61 vs.1.67) (p = 0.027). The clinical outcome score was 2.42 and 2.68 in patients who underwent complete EAC excision and those who underwent EAC fenestration only, respectively (p = 0.158). The mean EAC length was 5.04 vertebral body levels (range, 2-13). Six of the 51 patients (11.7 %) had multiple EACs., Conclusions: Total excision of EACs may have little benefit in terms of cyst recurrence and clinical outcome. The procedure for EAC resection carries a risk of complications such as kyphosis. If EAC resection is performed, we suggest that a tailored short-level laminotomy be used to allow for the repair of dural defects. Particularly in patients with small EAC, a partial hemilaminectomy with dural defect repair may be a possible method to reduce complications.

Objective: To evaluate the effects of cervical artificial disc replacement (ADR) and anterior discectomy and fusion (ACDF) on adjacent spinal alignments., Methods: The cohort consisted of 33 patients who undergone single-level cervical ADR (15 patients) and ACDF (18 patients) for radiculopathy, who had not had any previous spine surgery, and who had a minimum follow-up of 2 years. Whole-spine lateral radiographs were taken at the pre-operative and follow-up consultations. Cervical lordosis, thoracic kyphosis, lumbar lordosis, and sagittal balance were measured each time. The patients filled out pre-operative and follow-up functional evaluation forms including visual analogue scale (VAS) of neck and arm. The mean follow-up durations of patients who had cervical ADR and ACDF were 28 ± 5.0 and 30 ± 5.8 months, respectively. The patients having ACDF had the higher mean age (53 ± 9.0 years) than that of patients with cervical ADR (45 ± 11.7 years)., Results: The cervical lordosis and thoracic kyphosis in cervical ADR group increased significantly more than those of the ACDF group in follow-up assessment (P = 0.011 and 0.012). There was no significant change of lumbar lordosis in intra- and inter-group analyses. The follow-up sagittal balances for the cervical ADR and ACDF groups moved towards a neutral value. Although the follow-up neck and arm VAS of the both groups improved than those of the pre-operative status, the groups did not differ significantly except for a difference in neck VAS, which improved more after ADR., Conclusions: The remodeling of cervical and thoracic curves after cervical ADR and ACDF was coupled and complementary. Cervical ADR contributed the restorations of angulations of cervical and thoracic spines. The neck VAS improved more after cervical ADR than after ACDF.

Background Context: Improving the surgical outcome of nonambulatory patients with metastatic epidural spinal compression has been of great interest lately. Although there have been many reports regarding the surgical outcome of spinal metastasis, the surgical outcome in terms of the probability of operative success for nonambulatory patients has not been thoroughly described. If the probability of ambulatory recovery is known, the optimal surgical indications can be determined and implemented., Purpose: To predict the surgical outcome and probability of ambulatory resumption for nonambulatory patients with spinal metastasis., Study Design: Retrospective analysis., Patient Sample: The surgical outcomes of patients who could not ambulate independently because of spinal metastasis from 1987 to 2010 were analyzed., Outcome Measures: The primary end point was postoperative ambulatory status. The secondary end point was survival time., Methods: Fifty-seven patients who could not ambulate independently at the time of surgery were included in the study. We defined "independent ambulation" as a better functional status than Nurick Grade 3, which is defined as "difficulty in walking which was not so severe as to require someone's help to walk." Preoperatively, functional status was Nurick Grade 4 in 21 patients and Grade 5 in 36 patients. Weakness developed 10.5 ± 11.9 days (median, 7.0; range, 1-80) before the operation and steadily worsened. Patients were unable to walk starting from 3.6 ± 4.9 days (median, 1.8; range, 0.5-23) before the operation. The spinal metastases were circumferentially decompressed., Results: Postoperatively, 39 patients (68%) could walk. Complications occurred in 26% (15/57) of the patients, and the major complication rate was 12% (7/57). The mortality rate was 5% (3/57). The patient survival time was 287 ± 51 days (median, 128) after the operation. Postoperative ambulatory status (yes vs. no, p < .01) and occurrence of major complication (yes vs. no, p < .01) affected survival time. Overall, patients could walk for 193±41 days (median, 114) postoperatively. Motor grade (grade ≥ 4/5 vs. <4/5, p < .01) and the occurrence of a major complication (yes vs. no, p < .01) were significant factors for resumption of ambulation. The rate of ambulation resumption was 95% (20/21) in patients with a motor grade of 4 of 5, whereas it was 53% (19/36) in patients with a motor grade less than 4 of 5 (p < .01)., Conclusions: The survival time of nonambulatory patients was dependent on ambulation recovery. About 95% of the nonambulatory patients could walk after surgery, when the operation was done in a timely manner with good remaining motor function. However, given the short life expectancy and the considerable surgical complication rate, surgery should only be prudently recommended to patients with optimal indications., (Copyright © 2011 Elsevier Inc. All rights reserved.)

Background: Spinal hepatocellular carcinoma (HCC) metastases are increasing with improved survival of patients with HCC. However, its treatment outcome, particularly regarding functional outcome, has not been adequately investigated., Objective: To present the surgical outcome of spinal HCC metastases and demonstrate prognostic factors for survival and ambulation time., Methods: Thirty-three patients (30 males, 3 females) were retrospectively reviewed. Child-Pugh classification was used to assess hepatic function. Preoperatively, 19 patients could ambulate (group A) and 14 patients could not (group B). Preoperatively, 18 patients received conventional fractionated radiotherapy., Results: The spinal metastases were removed to achieve sufficient neural decompression. If destabilization developed, instrumentation and/or vertebroplasty were performed. Postoperatively, conventional radiotherapy was administered to 13 patients. Patients survived for 203 ± 31 days. Child-Pugh classification and preoperative/postoperative ambulatory ability were correlated with survival time, with Child-Pugh classification being the most significant factor (hazard ratio, 3.75; 95% confidence interval: 1.38-10.22). After the operation, ambulatory ability was maintained in all group A patients and was recovered in 4 in group B. Twenty-three patients could ambulate for 285 ± 62 days. Preoperative ambulatory status and Child-Pugh classification were correlated with a longer ambulatory period, with preoperative ambulatory status most significant (hazard ratio, 8.62; 95% confidence interval: 2.39-31.04). Patients died 81 ± 71 days after the loss of ambulatory ability, regardless of postoperative ambulatory status., Conclusion: In spinal HCC metastasis, ambulatory status and hepatic function were significantly correlated with survival and ambulation time. Both ambulatory status and hepatic function should be considered in the selection of surgical candidates.

The aim of this study was to analyze the clinical characteristics of thoracic ossified ligamentum flavum (OLF) and to elucidate prognostic factors as well as effective surgical treatment modality. The authors analyzed 106 thoracic OLF cases retrospectively from January 1999 to December 2008. The operative (n = 40) and the non-operative group (n = 66) were diagnosed by magnetic resonance imaging (MRI) and/or computed tomography (CT) imaging. We excluded cases exhibiting ventral compressive lesions causing subarachnoid space effacement in thoracic vertebrae as well as those with a coexisting cervical compressive myelopathy. Those in the operative group were treated with decompressive laminectomy as well as resection of OLF. The preoperative neurologic status and postoperative outcomes of patients, as indicated by their modified Japanese Orthopedic Association (mJOA) scores and recovery rate (RR), Modic changes, the axial (fused or non-fused) and sagittal (omega or beak) configurations of OLF, and the ratios of the cross-sectional area (CSA) and anteroposterior diameter (APD) of the most compressed level were studied. The most commonly affected segment was the T10-11 vertebral body level (n = 49, 27.1%) and the least affected segment was the T7-8 level (n = 1, 0.6%). The ratios of the CSA in non-fused and fused types were 77.3 and 59.3% (p < 0.001). When Modic changes were present with OLF, initial mJOA score was found to be significantly lower than those without Modic change (7.62 vs. 9.09, p = 0.033). Neurological status improved after decompressive laminectomy without fusion (preoperative vs. last mJOA; 7.1 ± 2.01 vs. 8.57 ± 1.91, p < 0.001). However, one patient exhibited transient deterioration of her neurological status after surgery. In the axial configuration, fused-type OLF revealed a significant risk for a decreased postoperative mJOA score (0-7, severe and moderate) (Odds ratio: 5.54, χ (2) = 4.41, p = 0.036, 95% CI: 1.014-30.256). The results indicated that the new categorization of axial-type of OLF is a helpful predictor of postoperative patient outcome and fused type was related with poor prognosis. In OLF cases free from ventral lesions compressing the spinal cord, decompressive laminectomy is enough for successful surgical outcome. Therefore, early surgical treatment will be considered in cases with fused-type OLF compressing spinal cord even though they do not have myelopathic symptoms.

Object: The aim of this study was to describe a novel technique for laminoplasty in which translaminar screws are used in the thoracic and lumbar spine., Methods: The authors first performed a morphometric study in 20 control individuals using 3D reconstructed CT scans and spine simulation software to measure the lengths and diameters of the spaces available for translaminar screw placement from the T-1 to S-1. Based on the results of the morphometric study, the authors then attempted translaminar screw fixation in 5 patients (April 2007-July 2007) after en bloc laminectomy in the thoracic and lumbar regions. All patients had intradural lesions: 3 schwannomas, 1 cavernoma, and 1 arachnoid cyst., Results: The morphometric study in control individuals revealed that the safe trajectories for simulated screws measured 25-30 mm in length and 8-11 mm in diameter in the thoracic region (T1-12) and 26-34 mm in length and 6-7 mm in diameter in the lumbosacral region (L1-S1). This morphometric and simulation study showed that translaminar screw placement would be possible in practice. Five patients underwent en bloc laminoplasty and translaminar screw fixation in which the screws measured 2.7 mm in diameter and 24 or 26 mm in length. Sixteen attempts at translaminar fixation were made in 8 vertebrae. Fourteen translaminar screws were successfully placed at the thoracic and lumbar levels. Two microplates had to be used because the laminae were too thin and narrow after further laminectomy with undercutting. There were no complications associated with the translaminar screws. The mean follow-up period was 14.5 months. There was no screw breakage or displacement. Solid osseous fusion was documented in 2 patients who underwent CT scanning 15 months postoperatively., Conclusions: The authors found that the laminoplasty and translaminar screw technique is feasible in the thoracic and lumbar regions, but further studies are needed to analyze the biomechanical effects and long-term outcomes in a large number of patients.

Paragangliomas of the cauda equina are rare neuroendocrine tumors. Four cases of nonsecreting paraganglioma of the cauda equina, preoperatively misdiagnosed as neurinoma, are presented with an emphasis on the correlation between magnetic resonance imaging findings and pathological features. Although it is difficult to correctly diagnose paraganglioma preoperatively for intradural extramedullary tumors, especially in the cauda equina, paraganglioma should be included in differential diagnoses.

Background Context: Conventional open procedures for lumbar pedicle screw instrumentation are often associated with significant morbidity resulting in longer postoperative recovery and hence have led to the advent of less invasive techniques of spinal instrumentation and fusion., Purpose: This study compares lumbar pedicle screw fixation and posterolateral fusion using endoscopic and open techniques in a sheep model., Study Design: Endoscopic and open techniques of lumbar pedicle screw instrumentation and posterolateral fusion are compared in a sheep model (12 sheep in each group). The safety and fusion outcome are assessed by postoperative computed tomography (CT) scans performed at 6 months., Methods: Twelve sheep underwent bilateral L4-L5 pedicle screw fixation and posterolateral fusion by means of endoscopic instrumentation and another 12 sheep by means of conventional open technique. For posterolateral fusions, an autologous iliac crest bone or bone graft substitute (Healos/MP52; Orquest, Mountain View, CA) was used on either the animal's left or right side. The animals were euthanized 6 months after surgery and the lumbar spines were harvested. Pedicle dimensions and screw insertion angles were measured and the two techniques were compared using CT and image analysis software. Pedicle screw misplacement was detected by means of direct inspection and CT scan, and fusions were evaluated by CT scans., Results: The endoscopic group's screw insertion angle was more convergent, corresponded more closely to the human pedicle angle and was less variable than in the open technique. Three of the endoscopic group's 48 screws were misplaced medially, whereas in the open technique, 5 screws were misplaced laterally. Posterolateral bone fusion masses were palpable 6 months after surgery for both the autologous bone grafts and graft substitutes. There were no complications. The ratio of screw to pedicle diameter was approximately 0.6, greater than in human studies., Conclusions: Despite differences between pedicle dimensions and screw angles, most screws could be inserted into the sheep pedicle using endoscopic or open techniques. Bone fusion was successful in both groups. Thus, minimally invasive, endoscopic transpedicular screw-plate fixation and posterolateral fusion is feasible, and as effective as the conventional open technique.

Objective: The goal of this study was to use a minimally invasive endoscopic surgical technique in a sheep model to evaluate the efficacy of an osteoinductive growth factor, recombinant human growth/differentiation factor-5 (also designated MP52), and an osteoconductive matrix formulation (Healos; DePuy AcroMed, Inc., Mountain View, CA) for inducing and facilitating bone formation., Methods: Twelve mature sheep underwent bilateral posterolateral lumbar fusion and pedicle screw fixation via a posterior endoscopic approach. Each sheep received two different types of graft material, autogenous iliac crest bone, or a bone graft substitute (MP52 with Healos), inserted into the right and left sides of the spine in an alternating fashion. Groups of four sheep were killed at 2, 4, and 6 months postoperatively for manual, radiographic, and histological evaluation., Results: No neurological impairments, infections, or other complications were observed. After 2 months, partial fusion on both sides was observed, but radiographic evaluation showed greater bone growth on the side that received the bone graft substitute. Solid posterolateral fusion was observed in both autograft and bone graft substitute sites at 4 and 6 months, and autograft and Healos MP52 fusion sites were essentially the same at histological examination. There was no abnormal overgrowth of new bone from either of these two materials., Conclusion: Endoscopic posterolateral lumbar arthrodesis and instrumentation is feasible, safe, and effective in a sheep model. Healos is a useful bonding agent that mimics natural bone in posterolateral intertransverse fusion sites. Combined with MP52, it produced fusion comparable to that of autogenous bone graft. Minimally invasive techniques and bone graft substitutes could eliminate morbidity and increase the likelihood of successful fusion.