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Dorsal arachnoid webs (DAWs) are rare pathological abnormalities of the arachnoid layer of the spinal cord that can result in pain and myelopathy.To present clinical, imaging, and pathological characteristics of patients diagnosed with DAW, case illustrations, and a review of the literature.Seventeen cases of DAW between 2015 and 2019 at a tertiary medical center were retrospectively identified through a case log search. Patient characteristics, preoperative imaging, operative notes, and pathology reports were collected. Our main outcome assessed was postoperative resolution of symptoms. Odds ratios were used to determine associations between preoperative signs and symptoms with postoperative symptom resolution.The mean age of the cohort was 50.5 years (IQR = 16) and presented primarily with back pain (64.7%). On imaging, all patients were found to have the "scalpel sign," and nearly half had a syrinx present (41.2%). All DAWs were located in the thoracic spine, with the most common location being the midthoracic (70.6%). The mean follow-up length for all patients was 4.3 months. There were no preoperative symptoms significantly associated with postoperative symptom resolution; however, a trend was noted with the presence of a preoperative syrinx. Pathology samples consistently demonstrated fibroconnective or collagenous tissue with no evidence of inflammation or neoplasm.DAW is a rare pathology that can result in myelopathy or inappropriate interventions if misdiagnosed. Surgical intervention using laminectomy with intradural exploration should be considered in symptomatic patients with DAW because it is curative with a strong chance of preoperative symptom resolution with relatively low complication rates.

OBJECTIVE High-grade spinal glioma (HGSG) is a rare but aggressive tumor that occurs in both adults and children. Histone H3 K27M mutation correlates with poor prognosis in children with diffuse midline glioma. However, the role of H3 K27M mutation in the prognosis of adults with HGSG remains unclear owing to the rarity of this mutation, conflicting reports, and the absence of multicenter studies on this topic. METHODS The authors studied a cohort of 30 adult patients with diffuse HGSG who underwent histological confirmation of diagnosis, surgical intervention, and treatment between January 2000 and July 2020 at six tertiary academic centers. The primary outcome was the effect of H3 K27M mutation status on progression-free survival (PFS) and overall survival (OS). RESULTS Thirty patients (18 males and 12 females) with a median (range) age of 50.5 (19–76) years were included in the analysis. Eighteen patients had H3 K27M mutation–positive tumors, and 12 had H3 K27M mutation–negative tumors. The median (interquartile range) PFS was 3 (10) months, and the median (interquartile range) OS was 9 (23) months. The factors associated with increased survival were treatment with concurrent chemotherapy/radiation (p = 0.006 for PFS, and p ≤ 0.001 for OS) and American Spinal Injury Association grade C or better at presentation (p = 0.043 for PFS, and p < 0.001 for OS). There were no significant differences in outcomes based on tumor location, extent of resection, sex, or H3 K27M mutation status. Analysis restricted to HGSG containing necrosis and/or microvascular proliferation (WHO grade IV histological features) revealed increased OS for patients with H3 K27M mutation–positive tumors (p = 0.017). CONCLUSIONS Although H3 K27M mutant–positive HGSG was associated with poor outcomes in adult patients, the outcomes of patients with H3 K27M mutant–positive HGSG were somewhat more favorable compared with those of their H3 K27M mutant–negative HGSG counterparts. Further preclinical animal studies and larger clinical studies are needed to further understand the age-dependent effects of H3 K27M mutation.

Lumbar spine synovial cysts develop from degenerated zygapophyseal joints. Symptomatic patients present with radicular pain and weakness or neurogenic claudication.1 In the absence of significant concomitant degenerative spondylolisthesis, symptomatic patients can be managed with a laminectomy and microsurgical resection of the cyst, without the need for instrumented fusion.2,3 In this video, we present the microsurgical resection of a left-sided L4-5 synovial cyst in a 68-yr-old man with radicular pain refractory to conservative management. The radiographical features, relevant surgical anatomy, and salient operative steps are reviewed, and strategies for preventing cyst recurrence are emphasized. There were no complications, the postoperative course was unremarkable, and the patient was discharged on postoperative day 1 with significant improvement in his presenting symptoms. No identifying information is present, and patient consent was obtained for the procedure and for publishing the material included in this video.

Objective Subependymomas are infrequent, low-grade gliomas associated with the ventricular system and the spinal cord. Little is known about the origin and natural history of these slow-growing lesions. Methods We identified all patients with pathologically proven subependymomas presenting to our institution between 1998 and 2016. We retrospectively reviewed clinical, radiographic, histologic, and surgical outcomes data in all patients who underwent surgical resection. Immunohistochemical analyses for cell lineage markers were performed. Results A total of 31 patients with pathologically proven subependymomas were identified. Of these, 7 asymptomatic lesions were discovered at autopsy and 24 symptomatic cases were treated surgically. There were 15 (48%) lateral ventricle tumors, 11 (35%) fourth ventricular tumors, and 5 (17%) spinal tumors. Symptomatic intracranial lesions most commonly presented with headaches and balance and gait abnormalities. Subependymomas had no distinguishing radiographic features that provided definitive preoperative diagnosis. At last follow-up, no patient treated surgically experienced recurrence. Immunohistochemical analyses demonstrated a diffusely GFAP-positive glial neoplasm with mixed populations of cells that were variably positive for Olig2, NHERF1, Sox2, and CD44. The Ki67 proliferation index was generally low ( Conclusions Subependymomas demonstrate mixed populations of cells expressing glial lineage markers as well as putative stem cell markers, suggesting these tumors may arise from multipotent glial progenitors that reside in the subventricular zone. Definitive diagnosis requires surgical sampling. Although the clinical course of subependymomas appears benign, the inability to radiographically diagnose these lesions, and the possibility of an alternative malignant lesion support a low threshold for early and safe maximal resection.

Intradural extramedullary tumors of the cervical spine are located within the dural sheath and outside the spinal cord. Nerve sheath tumors, including the subset of dumbbell tumors, and meningiomas make up the vast majority of these tumors. Using standard exposures and microsurgical techniques, it is possible to completely resect these tumors while preserving neurological function in most cases. Timely treatment on appropriate selected patients, combined with a well-developed plan for an operative approach, can lead to gratifying outcomes for both patient and surgeon. While benign, noninvasive, and biologically indolent, these tumors are subject to so many variables that each case must be considered unique. Key considerations of the tumors, including size, axial and sagittal location, origin, attachments, vascularity and consistency, as well as patient conditions and co-morbidities and surgeon preferences and experience, must all be incorporated into the treatment plan. In this chapter, we aim to describe the initial approach, surgical techniques, as well as modifications and pearls in order to optimize surgical management of these tumors.

This video demonstrates the microsurgical removal of an intramedullary spinal cord hemangioblastoma through an anterior cervical approach. While most spinal hemangioblastomas arise from the dorsal or dorsolateral pial surface and can be safely resected through a posterior approach,1,2 ventral tumors can present a significant challenge to safe surgical removal.3-5 This patient presented with a progressively symptomatic ventral pial based hemangioblastoma at the C5-6 level with large polar cysts extending from C3 to T1. The tumor was approached through a standard anterior cervical exposure with a C5 and C6 corpectomy. Following midline durotomy, the tumor was identified and complete microsurgical resection was achieved. The principles and techniques of tumor resection are illustrated and described in the video. Following tumor resection and dural closure, a fibular allograft was inserted into the corpectomy defect and a C4-C7 fixation plate was placed. The patient was maintained in a supine position for 36 h. He was discharged home on postoperative day 3 in a cervical collar. The patient did well with near-complete recovery of neurological function. Postoperative magnetic resonance imaging at 6 wk showed a substantial resolution of the polar cysts and no evidence of residual tumor. The patient featured in this video consented to the procedure.

OBJECT Cystic lesions in the atrium (trigone) of the lateral ventricle may become symptomatic due to obstruction of physiological CSF circulation and/or from mass effect on adjacent structures. A minimally invasive approach that not only allows for straightforward access to multiple regions of the atrial cyst wall, but also enables direct inspection of the entire lateral ventricular system, has not been elaborated. In this paper the authors describe their experience with the endoscopic transoccipital horn approach for treating cystic lesions in the atrium of the lateral ventricle. METHODS A retrospective review was performed of all patients who underwent endoscopic surgical treatment for cysts in the atrium of the lateral ventricle between 1999 and 2014. RESULTS The cohort consisted of 13 consecutive patients who presented with symptomatic lateral ventricular entrapment due to the presence of an atrial cyst. There were 9 male and 4 female patients, with a median age of 5 years. Headache was the most common complaint at presentation. The transoccipital horn approach facilitated successful cyst reduction and fenestration in all cases. Temporal and occipital horn entrapment was reversed in all cases, with reestablishment of a physiological CSF flow pattern throughout the ventricles. Hydrocephalus was also reversed in all patients presenting with this neuroimaging finding at presentation. No cyst or ventricular entrapment was noted to recur during a mean follow-up period of 36 months. No patient in the study cohort required repeat surgery or permanent CSF diversion postoperatively. CONCLUSIONS The endoscopic transoccipital horn approach represents a safe and effective treatment strategy for patients with symptomatic atrial cysts of the lateral ventricle. Using this minimally invasive technique, all poles of the lateral ventricular system can be visualized and the unobstructed flow of CSF can be confirmed after cyst resection obviating the need for additional diversion.

Spinal cavernous malformations are intramedullary vascular lesions. They have low pressure and flow, so they may take many years to present with clinical symptoms. Because of their relatively benign nature, surgical intervention is not always indicated. An understanding of the natural history of cavernous malformations helps make decisions about when and if to intervene. In patients who do not have surgery, 88.7% have stable or improved neurologic function, whereas 89.3% have these outcomes in the surgical group. Of note, 51.5% of patients were found to improve in the surgical group, compared to 30.2% in the nonsurgical group. Characteristics that correlated with better neurologic outcome were: resection within 3 months of the onset of symptoms, gross total resection, presentation with motor symptoms, and an acute course. Sensory symptoms correlated with worse outcome. Given the natural history of spinal cavernous malformations, surgery may be considered for symptomatic patients, when general medical health and lesion location permit safe resection. The severity of symptoms must also be considered, as the natural history of the disease can be benign.

Cervical spondylotic myelopathy (CSM) is the most common cause of spinal cord dysfunction in the world. There are significant practice variation and uncertainty as to the optimal surgical approach for treating CSM.To determine whether ventral surgery is associated with superior Short Form-36 Physical Component Summary outcome at the 1-year follow-up compared with dorsal (laminectomy/fusion or laminoplasty) surgery for the treatment of CSM, to investigate whether postoperative sagittal balance is an independent predictor of overall outcome, and to compare health resource use for ventral and dorsal procedures.The study is a randomized, controlled trial with a nonrandomized arm for patients who are eligible but decline randomization. Two hundred fifty patients (159 randomized) with CSM from 11 sites will be recruited over 18 months. The primary outcome is the Short Form-36 Physical Component Summary score. Secondary outcomes include disease-specific outcomes, overall health-related quality of life (EuroQOL 5-dimension questionnaire), and health resource use.This will be the first randomized, controlled trial to compare directly the health-related quality-of-life outcomes for ventral vs dorsal surgery for treating CSM.A National Institutes of Health-funded (1R13AR065834-01) investigator meeting was held before the initiation of the trial to bring multiple stakeholders together to finalize the study protocol. Study investigators, coordinators, and major stakeholders were able to attend and discuss strengths of, limitations of, and concerns about the study. The final protocol was approved for funding by the Patient-Centered Outcomes Research Institute (CE-1304-6173). The trial began enrollment on April 1, 2014.

Object Adult spinal deformity (ASD) surgery is increasing in the spinal neurosurgeon's practice. Methods A survey of neurosurgeon AANS membership assessed the deformity knowledge base and impact of current training, education, and practice experience to identify opportunities for improved education. Eleven questions developed and agreed upon by experienced spinal deformity surgeons tested ASD knowledge and were subgrouped into 5 categories: 1) radiology/spinopelvic alignment, 2) health-related quality of life, 3) surgical indications, 4) operative technique, and 5) clinical evaluation. Chi-square analysis was used to compare differences based on participant demographic characteristics (years of practice, spinal surgery fellowship training, percentage of practice comprising spinal surgery). Results Responses were received from 1456 neurosurgeons. Of these respondents, 57% had practiced less than 10 years, 20% had completed a spine fellowship, and 32% devoted more than 75% of their practice to spine. The overall correct answer percentage was 42%. Radiology/spinal pelvic alignment questions had the lowest percentage of correct answers (38%), while clinical evaluation and surgical indications questions had the highest percentage (44%). More than 10 years in practice, completion of a spine fellowship, and more than 75% spine practice were associated with greater overall percentage correct (p < 0.001). More than 10 years in practice was significantly associated with increased percentage of correct answers in 4 of 5 categories. Spine fellowship and more than 75% spine practice were significantly associated with increased percentage correct in all categories. Interestingly, the highest error was seen in risk for postoperative coronal imbalance, with a very low rate of correct responses (15%) and not significantly improved with fellowship (18%, p = 0.08). Conclusions The results of this survey suggest that ASD knowledge could be improved in neurosurgery. Knowledge may be augmented with neurosurgical experience, spinal surgery fellowships, and spinal specialization. Neurosurgical education should particularly focus on radiology/spinal pelvic alignment, especially pelvic obliquity and coronal imbalance and operative techniques for ASD.

The theme of the 80th Annual Meeting of the American Association of Neurological Surgeons and the title of this presidential address, “We are neurosurgery,” is a simple 3-word affirmation of who neurosurgeons are, what they have achieved, and how much there is yet to accomplish. Recent advances in neurobiology and the clinical neurosciences have brought an unprecedented understanding of the human nervous system in both health and disease. As a specialty, neurosurgery has translated knowledge, expanded techniques, and incorporated technology to exponentially expand the science and scope of neurosurgical practice. However, the rapidly advancing, divergently evolving growth of neurosurgery has had profound effects on all aspects of neurosurgery. In this address, the author examines the contemporary meaning of the annual meeting's theme as it relates to the science, practice, specialty, and profession of neurosurgery, as well as the neurosurgeon. In doing so, the author reveals his interpretation of “We are neurosurgery,” which he hopes will have an effect on others.

Object Access to the ventral intradural spinal canal may be required for treatment of a variety of lesions affecting the spinal cord and adjacent intradural structures. Adequate exposure is usually achieved through a standard posterior laminectomy or posterolateral approaches, although formal anterior approaches are used to access lesions in the subaxial cervical spine. Modifications of the standard posterior exposure as well as ventral or ventrolateral approaches are increasingly being used for treating intradural spinal pathologies. In this study, the authors review their experience with 35 consecutive cases of ventral intradural spinal lesions. Methods Only patients with intradural lesions located completely ventral to the dentate ligament attachments were included in this retrospective study. Patients with the following lesions were excluded from the study: lesions at the level of the filum terminale/cauda equina, lesions with any component that extended dorsally to the dentate ligament, or lesions with extradural extension (that is, dumbbell tumors) below the C-2 level. Between January 2000 and September 2009, a total of 35 patients (age range 17–72 years, mean 42.6 years) with ventral intradural spinal pathology underwent surgery at the authors' institution. Results There were 28 intradural extramedullary mass lesions: 15 meningiomas, 12 solitary schwannomas, and 1 neuroenteric cyst. Surgical approaches to these lesions included 23 posterior or posterolateral approaches, 4 anterior approaches with corpectomy followed by tumor resection and reconstruction, and 1 lateral transforaminal resection. No patient had evidence of instability at follow-up, which ranged from 6 months to 8 years in duration. One patient had worsened spinal cord function following surgery. There were 7 patients with intramedullary lesions: 2 hemangioblastomas, 2 cavernous malformations, 2 perimedullary fistulas, and 1 astrocytoma. All but 1 were superficial pia-based lesions arising ventral to the dentate ligament. Five of the 6 pia-based lesions were successfully resected via a standard posterior laminectomy, partial facetectomy with dentate section, and spinal cord rotation. One midline pial lesion was successfully removed with a minimally invasive retropleural thoracotomy. The astrocytoma was resected through an anterior cervical corpectomy, which was followed by instrumented reconstruction. There were no significant complications or neurological morbidity at follow-up (range 9 months–6 years). Conclusions Most intradural spinal lesions can be treated with contemporary microsurgical techniques with long-term control or cure of the lesion and preservation of neurological function. Standard posterior approaches provide adequate exposure to safely remove the vast majority of these lesions without the need for a potentially destabilizing resection of the facet or pedicle. Posterior exposures with varying degrees of lateral bone resection, dentate ligament division, and gentle cord rotation may also provide adequate exposure for safe removal of nonmidline ventrolateral superficial pial presenting spinal cord lesions. Nevertheless, in certain cases of ventral intradural lesions, anterior approaches are necessary and should be considered under appropriate circumstances.

Background and Purpose— Cognitive dysfunction occurs in 9% to 23% of patients during the first month after carotid endarterectomy (CEA). A 4-basepair (AAAT) tandem repeat polymorphism (either 3 or 4 repeats) has been described in the promoter region of inducible nitric oxide synthase (iNOS), a gene with complex roles in ischemic injury and preconditioning against ischemic injury. We investigated whether the 4-repeat variant (iNOS + ) affects the incidence of cognitive dysfunction after CEA. Methods— One-hundred eighty-five CEA and 60 spine surgery (control) subjects were included in this nested cohort analysis. Subjects underwent a battery of 7 neuropsychometric tests before and 1 day and 1 month after surgery. Multivariate logistic regression analyses were performed to determine if the iNOS promoter variant was independently associated with the incidence of cognitive dysfunction at 1 day and 1 month. Further, all right-hand-dominant CEA subjects were grouped by operative side and performance on each test was compared between iNOS + and iNOS − groups. Results— Forty-four of 185 CEA subjects had at least 1 iNOS promoter allele containing 4 copies of the tandem repeat (iNOS + ). iNOS + status was significantly protective against moderate/severe cognitive dysfunction 1 month after CEA. Right-hand-dominant iNOS + CEA subjects undergoing left-side CEA performed significantly better than iNOS − subjects on a verbal learning test and those undergoing right-side CEA performed significantly better on a test of visuospatial function. Conclusion— We demonstrate an iNOS promoter polymorphism variant provides protection against moderate/severe cognitive dysfunction 1 month after CEA. Further, this protection appears to involve cognitive domains localized ipsilateral to the operative carotid artery.

STUDY DESIGN Randomized clinical trial. OBJECTIVE.: To determine if age affects outcomes from differing treatments in patients with spinal metastases. SUMMARY OF BACKGROUND DATA Recently, class I data were published supporting surgery with radiation over radiation alone for patients with malignant epidural spinal cord compression (MESCC). However, the criteria to properly select candidates for surgery remains controversial and few independent variables which predict success after treatment have been identified. METHODS Data for this study was obtained in a randomized clinical trial comparing surgery versus radiation for MESCC. Hazard ratios were determined for the effect of age and the interaction between age and treatment. Age estimates at which prespecified relative risks could be expected were calculated with greater than 95% confidence to suggest possible age cut points for further stratification. Multivariate models and Kaplan-Meier curves were tested using stratified cohorts for both treatment groups in the randomized trial each divided into 2 age groups. RESULTS Secondary data analysis with age stratification demonstrated a strong interaction between age and treatment (hazard ratio = 1.61, P = 0.01), such that as age increases, the chances of surgery being equal to radiation alone increases. The best estimate for the age at which surgery is no longer superior to radiation alone was calculated to be between 60 and 70 years of age (95% CI), using sequential prespecified relative risk ratios. Multivariate modeling and Kaplan-Meier curves for stratified treatment groups showed that there was no difference in outcome between treatments for patients >or=65 years of age. Ambulation preservation was significantly prolonged in patients

✓Acquired intradural arachnoid cystic lesions of the spine have been associated with trauma, hemorrhage, parasitic infections, and other insults that cause inflammation and subarachnoid adhesions. The authors describe the case of a previously healthy 36-year-old woman who presented with a chronic myelopathy due to the progressive development of a giant spinal arachnoid cyst that resulted after the intrathecal injection of phenol for the management of chronic upper extremity pain. Neurological examination, spinal computed tomography, and magnetic resonance imaging were used for diagnostic and follow-up purposes. Even after the initial excision of the cyst, the patient remained symptomatic with minimal functional recovery.

✓Intramedullary inclusion cysts are extremely rare within the rostral spinal cord. In this case report the authors outline the clinical features and surgical treatment of one dermoid cyst and one epidermoid cyst of the cervicothoracic junction. The authors also include a relevant literature discussion regarding the treatment and the embryological origin of these lesions.

Study Design. In this Journal Club review, the study design, conduct, and analysis of Zdeblick's prospective, randomized trial comparing instrumented and noninstrumented posterolateral lumbar fusion, "A Prospective, Randomized Study of Lumbar Fusion: Preliminary Results," are examined. Objective. The objective of this paper is to review one of the most frequently cited papers published in Spine, to evaluate and discuss its methods and conclusions, and to understand its significance in light of subsequent research. of Background Data. At the time of publication (1993), there were no published studies comparing the fusion rates and clinical outcomes of noninstrumented and instrumented posterolateral lumbar fusion. Methods. The study protocol and methods were critically examined. The results as originally reported and as verified or modified by the reanalysis are discussed in their original context and based on ensuing studies. Results. The original paper reported a benefit with rigid pedicle screw fixation in both the proportion of patients achieving fusion and clinical outcome in patients with degenerative lumbar disease. The reanalysis demonstrated that the difference between the rigid fixation and noninstrumented groups persisted even after accounting for the postrandomization reassignment of patients. Although the difference in clinical outcome between the rigidly instrumented and noninstrumented groups was statistically significant, a nonvalidated, physician-based measure was used. Subgroup analyses of fusion did not reach statistical significance. Conclusions. This prospective, randomized trial demonstrated that, compared with noninstrumented posterolateral lumbar fusion, rigid pedicle screw fixation results in an increase in the proportion of patients achieving arthrodesis from 64% to 88%. It is not possible to generalize these results to other patient populations. Subsequent research by other investigators has generally confirmed the beneficial effect of rigid segmental fixation on achieving fusion, but a positive relationship between rigid fixation and clinical outcome has yet to be definitively demonstrated.

✓The long-anticipated results of the Spine Patient Outcomes Research Trial (SPORT) were recently published in the Journal of the American Medical Association. In this trial the investigators compared operative and nonoperative care in patients with symptomatic lumbar disc herniation. Despite the expenditure of several million dollars on this multi-center, prospective, randomized, controlled clinical trial, the SPORT investigators admitted, “conclusions about the superiority or equivalence of the treatments under study are not warranted based on the intent-to-treat analysis.” In the present article the author provides a critical review of the SPORT formulation and hypothesis, study design and methodology, and results and interpretations in an attempt to explain why the authors of this study were unable to assess the study's only intended null hypothesis that there would be no difference in outcomes between operative and nonoperative management of herniated lumbar discs. Issues related to misrepresentation and misinterpretation of the SPORT results for herniated lumbar discs are also assessed.

The risk of postoperative cancer following the use of recombinant human bone morphogenetic protein (BMP)–2 in spinal fusion is one potential complication that has received significant interest. Until recently, there has been little clinical evidence to support the assertion of potential cancer induction after BMP use in spinal surgery. This report aims to summarize the findings from clinical data available to date from the Yale University Open Data Access (YODA) project as well as more recently published large database studies regarding the association of BMP use in spinal fusion and the risk of postoperative cancer. A detailed review was based on online databases, primary studies, FDA reports, and bibliographies of key articles for studies that assessed the efficacy and safety of BMP in spinal fusion. In an analysis of the YODA project, one meta-analysis detected a statistically significant increase in cancer occurrence at 24 months but not at 48 months, and the other meta-analysis did not detect a significant increase in postoperative cancer occurrence. Analysis of 3 large health care data sets (Medicare, MarketScan, and PearlDiver) revealed that none were able to detect a significant increase in risk of malignant cancers when BMP was used compared with controls. The potential risk of postoperative cancer formation following the use of BMP in spinal fusion must be interpreted on an individual basis for each patient by the surgeon. There is no conclusive evidence that application of the common formulations of BMP during spinal surgery results in the formation of cancer locally or at a distant site.

STUDY DESIGN Cost-effectiveness analysis with retrospective cost analysis and literature review. OBJECTIVE To determine the relative cost-effectiveness of anterior cervical discectomy and fusion (ACDF) with autograft, allograft, and allograft with plating for single-level anterior cervical spondylosis. SUMMARY OF BACKGROUND DATA There are several accepted methods of surgically treating single-level cervical spondylosis anteriorly. No study has clearly demonstrated the superiority of one method over the alternatives. The techniques may differ in their operative risks and resource use, perioperative complications, short-term outcome, and long-term outcome and complications. Formal cost-effectiveness analysis (CEA) provides a structure for analyzing many variables and comparing different treatment outcomes. Sensitivity analysis is used to test the robustness of the model and to determine variables that have significant effects on the results. Future areas of research and refinements of the CEA model can be developed from these findings. METHODS A retrospective review of hospital charges was performed for 78 patients who underwent single-level ACDF with allograft alone or ACDF with allograft and plating (ACDFP). The charges were converted to estimated costs for fiscal year 2000 using the ratio of costs to charges method. A CEA model was developed consisting of a decision-analysis model for the first year postsurgery and a Markov model for the next 4 years after surgery. Probabilities and outcome utilities were estimated from the literature. Outcome was measured in quality-adjusted life years (QALYs), and incremental CEA was performed. Several variables were tested in one-way sensitivity analysis. RESULTS Compared with ACDF with autograft, ACDF with allograft offered an improvement in quality of life at a cost of 496 dollars per QALY. ACDFP provided additional gains in quality of life compared with ACDF with allograft at a cost of 32,560 dollars per QALY in the base case analysis. In sensitivity analysis, these estimates varied between 417 dollars and 741 dollars per QALY and between 19,090 dollars per QALY and domination of ACDFP by ACDF with allograft, respectively. The results were most sensitive to assumptions regarding differences in the length of the postoperative recovery period. CONCLUSIONS ACDF with allograft offers a benefit relative to ACDF with autograft at a cost of 496 dollars per QALY. ACDFP has a benefit relative to ACDF with allograft at an approximate cost of 32,560 dollars per QALY. CEA provides a method for comparing the benefits and risks of these three procedures. Further research needs to be performed regarding these procedures, particularly examining the postoperative recovery period.

The management of patients with intradural spinal tumors differs in many respects from approaches taken for patients with intracranial tumors. Intramedullary lesions are often completely surrounded by normal spinal cord, displacing vital functional tracts eccentrically. Extramedullary lesions can drastically compress the spinal cord and nerve roots, reducing normal tissue to a ribbon-like consistency. The small amount of normal tissue relative to tumor has implications for surgery and postoperative adjuvant therapy. In addition, operative intervention must take spinal stability into consideration. In this report, we describe the current best care practices and strategies for patients with a diagnosis of spinal astrocytoma, ependymoma, hemangioblastoma, schwannoma, and meningioma. Treatment of patients with intradural tumors of the spinal cord and adjoining structures has changed over the past 20 years. Advances in many disciplines including neuroradiology, neurosurgery, neurooncology, and neuropathology have contributed to expediting diagnosis and improving outcomes.

OBJECTIVE AND IMPORTANCE: Spinal cord schwannomas are intradural nerve sheath tumors that almost universally occupy a dorsolateral, lateral, or ventrolateral position. Therefore, resection of these lesions typically proceeds via a posterior or posterolateral approach. CLINICAL PRESENTATION: We present a case of a midline ventral intradural schwannoma of the cervical spinal cord causing myelopathy. To the best of our knowledge. no previous reparts specifically discuss purely midline ventral intradural schwannomas. INTERVENTION: Resection of the tumor was performed via an anterior cervical corpectomy with spinal arthrodesis and fixation. We review possible causes for such corpectomy with spinal arthrodesis and fixation. We review possible causes for such an anomaious location for schwannoma as well as the advantages and disadvantages of various surgical strategies for removing the tumor. CONCLUSION: This case exemplities the usefulness of anterior approaches to the cervical spine in treating unusual intradural spinal cord tumors.

STUDY DESIGN: A national hospitalization database was used to determine rates and trends in the treatment of cervical disc disease. OBJECTIVE: To examine the temporal and geographic variations in hospitalizations and surgical procedures for cervical disc disease. SUMMARY OF BACKGROUND DATA: Studies of spinal surgery during the 1980s showed significant increases in the rates for all procedures, particularly those involving fusion. The management of cervical disc disease continues to be controversial. METHODS: Data from the National Hospital Discharge Survey from 1990 through 1999 were analyzed. Records were selected and categorized according to an algorithm of International Classification of Diseases (ICD-9) procedure and diagnosis codes. RESULTS: During the study period, the rate of hospitalization for surgical and nonsurgical treatment of cervical disc disease did not increase significantly. There was, however, a statistically significant increase in the proportion of hospitalizations for the surgical treatment of cervical disc disease that included a fusion procedure. There also was significant geographic variation in the rate of fusion procedures, with the South having the highest rate. CONCLUSIONS: Although the rate of surgery for cervical disc disease did not increase significantly during the 1990s, the rate of fusion procedures did rise significantly.

Ependymomas are the most common intramedullary spinal cord tumor in adults. With complete microsurgical resection, the recurrence rate of these tumors is very low. The strongest predictor of postoperative neurological function is preoperative disability. All intramedullary spinal cord tumors that may prove to be ependymomas should be approached with the goal of total resection. Intraoperative monitoring may help surgeons to preserve neurological function. Histological examination of the tumor intraoperatively may assist surgical decision-making, but it must be considered in the context of the gross appearance of the tumor, particularly the existence of a dissectable plane between the tumor and the spinal cord. If gross total resection is achieved, postoperative adjunctive therapy is unnecessary, and the patient should be followed radiographically for recurrence.

OBJECTIVE: Expansile laminoplasty has been successfully used to treat cervical myelopathy attributable to canal stenosis. However, detachment of the posterior cervical muscles is thought to contribute to postoperative axial neck pain and kyphosis. Minimizing the amount of muscular dissection might reduce the likelihood of these sequelae. METHODS: Six human cadaveric spines were used to assess the feasibility of a minimally invasive laminoplasty technique. A 22-mm tubular dilator port was used to access the lamina-facet junctions from C2 to C7, through bilateral stab incisions at C4-C5 and C5-C6. Troughs at the lamina-facet junctions were drilled bilaterally, and the contiguous laminae were lifted en bloc from one side. Ten-millimeter rib allograft spacers were inserted to maintain a gap on the open side. RESULTS: Exposure of six cervical levels was easily accomplished with two small incisions on each side. Drilling was achieved without dural violations. The midsagittal spinal canal diameter was increased by a mean of 38% and the spinal canal area was increased by an average of 43% at the level of C5. CONCLUSION: A minimally invasive approach for cervical laminoplasty could be performed in human cadavers. The measured increases in spinal canal space approximated those demonstrated to be associated with stabilization or improvement of neurological status.

OBJECTIVE Several authors have noted increased neurological deficits and worsening dysesthesia in the postoperative period in patients with spinal cord ependymoma. We describe the neurological progression and pain evolution of these patients over the 1-year period after surgery. In addition, our favored method of en bloc tumor resection is illustrated, and the rate of complications, recurrence, and survival in this group of patients is addressed. METHODS We operated on 26 patients (12 male and 14 female) with low-grade spinal cord ependymomas between 1975 and 2001. The median age at diagnosis was 42 years. Tumors extended into the cervical cord in 13 patients, the thoracic cord in 7 patients, and the conus medullaris in 6 patients. Eleven patients had previous surgery and/or radiation therapy. RESULTS We achieved a gross total resection in 88% of patients, whereas 8% had a subtotal resection and 4% had a biopsy. Only 1 patient developed a recurrence over a mean follow-up period of 31 months. CONCLUSION We conclude that radical surgical resection of spinal cord ependymomas can be safely achieved in the majority of patients. A trend toward neurological improvement from a postoperative deficit can be expected between 1 and 3 months after surgery and continues up to 1 year. Postoperative dysesthesias begin to improve within 1 month of surgery and are significantly better by 1 year after surgery. The best predictor of outcome is the preoperative neurological status.

OBJECTIVEResection of intramedullary spinal cord tumors may result in transient or permanent neurological deficits. Intraoperative somatosensory evoked potentials (SSEPs) and motor evoked potentials are commonly used to limit complications. We used both antidromically elicited SSEPs for planning the myelotomy site and direct mapping of spinal cord tracts during tumor resection to reduce the risk of neurological deficits and increase the extent of tumor resection.METHODSIn two patients, 3 and 12 years of age, with tumors of the thoracic and cervical spinal cord, respectively, antidromically elicited SSEPs were evoked by stimulation of the dorsal columns and were recorded with subdermal electrodes placed at the medial malleoli bilaterally. Intramedullary spinal cord mapping was performed by stimulating the resection cavity with a handheld Ojemann stimulator (Radionics, Burlington, MA). In addition to visual observation, subdermal needle electrodes inserted into the abductor pollicis brevis-flexor digiti minimi manus, tibialis anterior-gastrocnemius, and abductor halluces-abductor digiti minimi pedis muscles bilaterally recorded responses that identified motor pathways.RESULTSThe midline of the spinal cord was anatomically identified by visualizing branches of the dorsal medullary vein penetrating the median sulcus. Antidromic responses were obtained by stimulation at 1-mm intervals on either side of the midline, and the region where no response was elicited was selected for the myelotomy. The anatomic and electrical midlines did not precisely overlap. Stimulation of abnormal tissue within the tumor did not elicit electromyographic activity. Approaching the periphery of the tumor, stimulation at 1 mA elicited an electromyographic response before normal spinal cord was visualized. Restimulation at lower currents by use of 0.25-mA increments identified the descending motor tracts adjacent to the tumor. After tumor resection, the tracts were restimulated to confirm functional integrity. Both patients were discharged within 2 weeks of surgery with minimal neurological deficits.CONCLUSIONAntidromically elicited SSEPs were important in determining the midline of a distorted cord for placement of the myelotomy incision. Mapping spinal cord motor tracts with direct spinal cord stimulation and electromyographic recording facilitated the extent of surgical resection.

Lumbar discectomy is generally performed to reduce pain or disability and thereby improve quality of life. Important surgery-related results, therefore, include the patients' perceptions of the effect of surgery on their health and ability to perform daily tasks. Spine surgeons should have an understanding of basic concepts of outcome measurement and be able to select appropriate questionnaires and incorporate them into their clinical practices and research. A brief review of the fundamental principles of outcome research is presented, and the recent lumbar discectomy literature concerning these ideas is summarized. Properly designed, conducted, and reported outcome studies of lumbar discectomy will assist the spine surgeon in selecting appropriate patients for surgery, educating them regarding expected results, and comparing this procedure with novel treatments for lumbar disc disease.

Ventral thoracic spinal cord herniation is a rare but increasingly recognized cause of progressive myelopathy. This video demonstrates the imaging characteristics and surgical techniques for release and reduction of the spinal cord herniation as well as primary repair and reinforcement of the ventral dural hernia defect through an extended posterior approach. An instrumented fusion was concomitantly performed.The video can be found here: http://youtu.be/6Pcokep6Tug.

Dumbbell tumors of the cervical spine can present considerable management challenges related to adequate exposure of both intraspinal and paraspinal tumor components, potential injury to the vertebral artery, and spinal stability. This video demonstrates the microsurgical removal of a large cervical dumbbell schwannoma with instrumented fusion via a single stage extended posterior approach. The video shows patient positioning, tumor exposure, and the sequence and techniques of tumor resection, vertebral artery identification and protection, and dural repair.The video can be found here: http://youtu.be/3lIVfKEcxss.

There are several non-neoplastic lesions which may mimic intramedullary spinal cord neoplasm in their radiographic and clinical presentation. These can be classified as either infectious (TB, fungal, bacterial, parasitic, syphilis, CMV, HSV) and non-infectious (sarcoid, MS, myelitis, ADEM, SLE) inflammatory lesions, idiopathic necrotizing myelopathy, unusual vascular lesions (amyloid, infarct, isolated intramedullary vascular lesions) and radiation myelopathy. Although biopsy may be indicated in many cases, the mistaken diagnosis of intramedullary neoplasm can often be eliminated pre-operatively.

Intramedullary ependymomas are rare tumors but comprise the majority of intramedullary glial neoplasms in the adult. These tumors are benign, slow-growing lesions which are optimally treated with gross-total surgical resection without adjuvant therapy. This objective can be attained safely in a majority, of patients. Post-operative functional outcome is related to pre-operative functional status. Hence, early diagnosis, prior to symptomatic progression, is critical to the successful treatment of these tumors. Adjuvant therapy is indicated for the rare malignant or disseminated tumor or following sub-total resection.

The advent of molecular biology has provided tools to delineate genetic mutations that cause disease. Recently, several genetic mutations have been associated with intramedullary spinal cord tumors. Concurrently, advances in micro-neurosurgical techniques have significantly decreased the morbidity of surgical resection. In this review, we describe the current understanding of genetic mutations in sporadic and familial intramedullary spinal cord tumors. The future success of innovative gene therapy protocols may depend upon establishing a cause and effect relationship between these genetic mutations and disease progression. Successful gene therapy will also depend upon increasing the efficiency of gene therapy vector delivery.

Sagittal balance is a concept familiar to spine deformity surgeons. Postural imbalance with displacement of the patient’s center of gravity anteriorly to the sacrum due to spinal disease is biomechanically disadvantageous and may cause significant pain and ambulatory difficulty. The evaluation of patients with sagittal imbalance involves a careful assessment of the thoracic kyphosis, lumbar lordosis, and pelvic angulation. Surgical planning prior to operative treatment involves careful study to determine the correct location and amount of sagittal angulation that needs to be achieved to create neutral sagittal balance. Equally important is the preservation of neutral sagittal alignment in patients without sagittal imbalance who undergo fusion in which instrumentation is placed from the lumbosacral spine to the pelvis; these patients possess a

Surgical treatment of diseases involving the thoracolumbar spine offers a unique challenge to the spine surgeon. Although more familiar posterior techniques are useful for a variety of thoracolumbar problems, the management of disease in this region is often optimized by an anterior approach. Thoracolumbar surgery requires an understanding of the relevant surgical anatomy, the pathologic processes affecting this region, and the relative indications and contraindications for particular operative strategies. It is also essential to be familiar with the management of potential morbidity, methods for avoiding complications, and the selection of particular fusion techniques and instrumentation devices associated with specific operative strategies.

Patient care data will soon inform all areas of health care decision making and will define clinical performance. Organized neurosurgery believes that prospective, systematic tracking of practice patterns and patient outcomes will allow neurosurgeons to improve the quality and efficiency and, ultimately, the value of care. In support of this mission, the American Association of Neurological Surgeons, in cooperation with a broad coalition of other neurosurgical societies including the Congress of Neurological Surgeons, Society of Neurological Surgeons, and American Board of Neurological Surgery, created the NeuroPoint Alliance (NPA), a not-for-profit corporation, in 2008. The NPA coordinates a variety of national projects involving the acquisition, analysis, and reporting of clinical data from neurosurgical practice using online technologies. It was designed to meet the health care quality and related research needs of individual neurosurgeons and neurosurgical practices, national organizations, health care plans, biomedical industry, and government agencies. To meet the growing need for tools to measure and promote high-quality care, NPA collaborated with several national stakeholders to create an unprecedented program: the National Neurosurgery Quality and Outcomes Database (N2QOD). This resource will allow any US neurosurgeon, practice group, or hospital system to contribute to and access aggregate quality and outcomes data through a centralized, nationally coordinated clinical registry. This paper describes the practical and scientific justifications for a national neurosurgical registry; the conceptualization, design, development, and implementation of the N2QOD; and the likely role of prospective, cooperative clinical data collection systems in evolving systems of neurosurgical training, continuing education, research, public reporting, and maintenance of certification.