The fate of spinal schwannomas following subtotal resection: a retrospective multicenter study by the Korea spinal oncology research group

A Complete Facet Resection and Cervical Pedicle Screw Placement Enhances Both Gross Total Resection and Motion Preservation for the Cervical Spinal Dumbbell Tumor

OBJECTIVE

To describe single-index-level fusion surgery using a cervical pedicle screw (CPS) after the complete facet resection of spinal dumbbell tumors and to compare it with partial facet resection without fusion.

METHODS

We retrospectively reviewed patients who underwent surgery for dumbbell-shaped cervical spine tumors. They were categorized into the fused group (complete facet resection with fusion using CPS) and the unfused group (partial facet resection without fusion). We compared demographics, tumor characteristics, resection rates (gross total, subtotal, or partial), and regrowth rates between the groups. Complete facet resection was performed for maximal tumor removal. In the fused group, single-index-level fusion was achieved using CPS. Despite tumor-associated erosion of the index vertebra's pedicle and/or lateral mass, the CPS was directly inserted into the vertebral body through an imaginary virtual pedicle without a lateral mass or pedicle purchase.

RESULTS

A total of 34 patients underwent surgery for dumbbell-shaped cervical tumors; half were classified into each group. There were no significant differences in demographic or tumor characteristics, including Asazuma classification, or histological diagnosis (P > 0.05). However, the gross total resection rate was significantly higher in the fused group (16/17, 94.1% vs. 9/17, 52.9%; P value = 0.011). Tumor recurrence was observed in 3 (17.6%) patients in the unfused group; no recurrence (0%) occurred in the fused group.

CONCLUSIONS

Complete facet resection with fusion using CPS significantly increased the gross total tumor removal rate, compared with partial resection without fusion. Therefore, CPS improved fusion surgery for maximal motion preservation, resulting in single-level fusion surgery.

Epidemiology, tumour characteristics, treatment and outcomes associated with spinal nerve sheath tumours: a systematic review protocol

INTRODUCTION

Nerve sheath tumours arise from both the central and peripheral nervous systems. In particular, cases of spinal or paraspinal origins are scarce and poorly covered in the literature. This systematic review aims to summarise the body of evidence regarding spinal nerve sheath tumours and assess its quality, to provide the current knowledge on epidemiology, tumour characteristics, diagnostics, treatment strategies and outcomes.

METHODS AND ANALYSIS

Databases including PubMed, Web of Science and Embase will be searched using keywords such as "spinal", "nerve sheath", "neurofibroma", "schwannoma", "neurinoma" and "neurilemoma". The search will be limited to studies published no earlier than 2000 without language restrictions. Case reports, editorials, letters and reviews will be excluded. Reference lists of identified studies will be searched to find possible additional relevant records. Identified studies will be screened for inclusion, by one reviewer at first and then two independent ones in the next step to increase the external validity. The Rayyan platform will be used for the screening and inclusion process. Data extraction within several predetermined areas of interest will proceed. Subjects of interest include epidemiology, histopathology, radiological diagnostics, surgery, complications, non-surgical treatment alternatives, disease outcomes and predictors of outcome, and recurrence rates. On satisfactory amount of homogenous data, a meta-analysis of key outcomes such as recurrence risk or postoperative neurological improvement will be performed. This systematic review will primarily serve as a reference guide to aid in diagnosis and treatment of patients with spinal schwannomas, while also spotlighting the knowledge gaps in the literature to help guide future research initiatives.

ETHICS AND DISSEMINATION

Ethics approval is not required for the protocol or review as both are based on existing publications. For dissemination, the final manuscript will be submitted to a peer-reviewed journal.

Spinal Schwannoma Classification Based on the Presumed Origin With Preoperative Magnetic Resonance Images

OBJECTIVE

Classification guides the surgical approach and predicts prognosis. However, existing classifications of spinal schwannomas often result in a high 'unclassified' rate. Here, we aim to develop a new comprehensive classification for spinal schwannomas based on their presumed origin. We compared the new classification with the existing classifications regarding the rate of 'unclassified'. Finally, we assessed the surgical strategies, outcomes, and complications according to each type of the new classification.

METHODS

A new classification with 9 types was created by analyzing the anatomy of spinal nerves and the origin of significant tumor portions and cystic components in preoperative magnetic resonance images. A total of 482 patients with spinal schwannomas were analyzed to compare our new classification with the existing classifications. We defined 'unclassified' as the inability to classify a patient with spinal schwannoma using the classification criteria. Surgical approaches and outcomes were also aligned with our new classification.

RESULTS

Our classification uniquely reported no 'unclassified' cases, indicating full applicability. Also, the classification has demonstrated usefulness in predicting the surgical outcome with the approach planned. Gross total removal rates reached 88.0% overall, with type 1 and type 2 tumors at 95.3% and 96.0% respectively. The approach varied with tumor type, with laminectomy predominantly used for types 1, 2, and 9, and facetectomy with posterior fixation used for type 3 tumors.

CONCLUSION

The new classification for spinal schwannomas based on presumed origin is applicable to all spinal schwannomas. It could help plan a surgical approach and predict its outcome, compared with existing classifications.

Surgical Strategy for Dumbbell-Shaped Cervical Schwannoma at the Vicinity of the Vertebral Artery: The Utilization of Anatomic Layer

BACKGROUND AND OBJECTIVES

In cases where dumbbell-shaped cervical schwannoma encases the vertebral artery (VA), there is a risk of VA injury during surgery. The objective of this study is to propose a strategy for preserving the VA during the surgical excision of tumors adjacent to the VA through the utilization of anatomic layers.

METHODS

A retrospective analysis was conducted on 37 patients who underwent surgery for dumbbell-shaped cervical schwannoma with contacting VA from January 2004 to July 2023. The VA encasement group consisted of 12 patients, and the VA nonencasement group included 25 patients.

RESULTS

The perineurium acted as a protective barrier from direct VA exposure or injury during surgery. However, in the VA encasement group, 1 patient was unable to preserve the perineurium while removing a tumor adjacent to the VA, resulting in VA injury. The patient had the intact dominant VA on the opposite side, and there were no new neurological deficits or infarctions after the surgery. Gross total resection was achieved in 25 patients (67.6%), while residual tumor was confirmed in 12 patients (32.4%). Four patients (33.3% of 12 patients) underwent reoperation because of the regrowth of the residual tumor within the neural foramen. In the case of the 8 patients (66.7% of 12 patients) whose residual tumor was located outside the neural foramen, no regrowth was observed, and there was no recurrence of the tumor within the remaining perineurium after total resection.

CONCLUSION

In conclusion, when resecting a dumbbell-shaped cervical schwannoma contacting VA, subperineurium dissection prevents VA injury because the perineurium acts as a protective barrier.

Quantitative Analysis of the Effect of Stereotactic Radiosurgery for Postoperative Residual Cervical Dumbbell Tumors: A Multicenter Retrospective Cohort Study

OBJECTIVE

Stereotactic radiosurgery (SRS) has been performed for spinal tumors. However, the quantitative effect of SRS on postoperative residual cervical dumbbell tumors remains unknown. This study aimed to quantitatively evaluate the efficacy of SRS for treating postoperative residual cervical dumbbell tumors.

METHODS

We retrospectively reviewed cases of postoperative residual cervical dumbbell tumors from 1995 to 2020 in 2 tertiary institutions. Residual tumors underwent SRS (SRS group) or were observed with clinical and magnetic resonance imaging (MRI) follow-up (observation group). Tumor regrowth rates were compared between the SRS and observation groups. Additionally, risk factors for tumor regrowth were analyzed.

RESULTS

A total of 28 cervical dumbbell tumors were incompletely resected. Eight patients were in the SRS group, and 20 in the observation group. The mean regrowth rate was not significantly lower (p = 0.784) in the SRS group (0.18 ± 0.29 mm/mo) than in the observation group (0.33 ± 0.40 mm/mo). In the multivariable Cox regression analysis, SRS was not a significant variable (hazard ratio [HR], 0.57; 95% confidence interval [CI], 0.18-1.79; p = 0.336).

CONCLUSION

SRS did not significantly decrease the tumor regrowth rate in our study. We believe that achieving maximal resection during the initial operation is more important than postoperative adjuvant SRS.

Long-Term Functional Outcomes Following Surgical Treatment of Spinal Schwannomas: A Population-Based Cohort Study

Spinal schwannomas are the second most common form of primary intradural spinal tumor. Despite being benign, they may cause spinal cord compression and subsequently acute or chronic neurological dysfunction. The primary treatment is surgical resection. The aim of this study was to identify pre- and postoperative predictors of favorable outcomes after surgical treatment for spinal schwannoma. All adult patients surgically treated for spinal schwannoma between 2006 and 2020 were eligible for inclusion. Medical records and imaging data were retrospectively reviewed. The primary outcome measures were neurological improvement according to the modified McCormick Scale (mMC) and changes in motor deficit, sensory deficit, gait disturbance, bladder dysfunction, and pain at long-term follow-up. In total, 180 patients with a median follow-up time of 4.4 years were included. Pain was the most common presenting symptom (87%). The median time between symptom presentation and surgery was 12 months, while the median time between diagnosis (first MRI) and surgery was 3 months. Gross total resection (GTR) was achieved in 150 (83%) patients and the nerve root could be preserved in 133 (74%) patients. A postoperative complication occurred in 10 patients (5.6%). There were significant postoperative improvements in terms of motor, sensory, gait, and bladder functions, as well as pain (p < 0.001). Of these symptoms, bladder dysfunction was the one most often improved, with complete symptom resolution in all cases. However, no other predictors of improvement could be identified. There were three cases of recurrence after GTR and nine cases of regrowth after STR. Reoperation was performed in six (3.3%) cases. GTR was associated with a significant improvement in neurological status at long-term follow-up and increased the chance of progression-free survival.

Factors predicting recurrence in benign spinal nerve sheath tumors: A retrospective study of 457 patients from a single institution

BACKGROUND

Benign Nerve sheath tumors (NST) comprise almost one-third of primary spinal tumours. The majority are sporadic. They have low rates of recurrence but an occasional recurrence may need re-surgery. The present study was designed to identify the variables that can predict the risk of their recurrence.

METHODS

A retrospective chart review was done including all the histologically proven benign spinal NSTs operated between 2001 and 2019 in our institute. Demographic, operative and postoperative follow-up data were recorded. Recurrence was defined as local reappearance after definite surgical excision or symptomatic increase in size of a residual tumour on follow-up imaging studies. Statistical analysis was done to determine the significant variables associated with local recurrence.

RESULTS

457 patients with a median age of 38 years operated for 459 NSTs qualified for the study. The most frequent location of occurrence of tumours was found to be Low Cervical level (C3-C7 levels). Majority of Schwannoma were located intradurally while Neurofibroma were dumb-bell shaped and extradural. Most of the tumours had solid consistency. Post operatively, 7.7% patients developed complications. 7.8% tumours developed local recurrence after median period of 12 months. The patients developing recurrence were younger compared to nonrecurring tumors. On univariate analysis, male gender, Low cervical and Cervicothoracic junction location were associated with higher recurrence. On multivariate analysis, location at Cervicothoracic junction reached significance.

CONCLUSION

Overall recurrence risk among all NST was 7.8% with a median progression free survival of 36 months. The location of tumour at cervicothoracic location was the significant risk factors for recurrence of tumour in our study.

Spinal Nerve Sheath Tumors: Factors Associated with Postoperative Residual and Recurrent Tumors: A Single-Center Experience

BACKGROUND

Spinal schwannomas (SSs) are usually benign tumors with a good prognosis when treated by surgical excision. However, complete resection can be complicated by factors such as the tumor location and configuration. In the present study, we sought to identify the factors associated with incomplete surgical resection (residual) and the factors associated with tumor recurrence.

METHODS

We performed a retrospective review of 113 cases of SSs treated surgically from 2008 to 2021.

RESULTS

Of the 113 SSs, 102 were benign and 2 were malignant nerve sheath tumors. Of the 102 benign SSs, gross total resection (GTR) was performed for 87, with 8 displaying residual and 7, recurrent tumor. We found a significantly higher ratio of cervical and sacral tumors (P = 0.008 and P = 0.004, respectively), dumbbell and foraminal configurations (P < 0.0001 and P = 0.0006, respectively), and larger tumor volumes (P = 0.003) in the residual and recurrent cohorts compared with the GTR cohort. A second operation was performed for 2 patients in the residual and 4 patients in the recurrent cohorts. The total complication rate was 6%.

CONCLUSIONS

We found that most benign SSs will be amenable to GTR (85% of cases), with an excellent prognosis. The patients with residual or recurrent tumor were more likely to have had a cervical or sacral location, a dumbbell or foraminal configuration, and a larger tumor volume. Except for 1 new SS and 1 recurrent tumor that had necessitated a lateral approach, the remainder had been treated using a posterior approach. At surgery, ultrasonography of the canal is advisable to ensure that the intra- and extraspinal components of dumbbell lesions have both been entirely removed.

Risk factors for recurrence and regrowth of spinal schwannoma

BACKGROUND

Spinal schwannoma recurs after initial surgery at a rate of 4%-6%, with known risk factors including subtotal resection, multilevel involvement, large tumor size, and malignant histopathology. This study examined risk factors for schwannoma recurrence and residual tumor regrowth.

METHODS

Sixty-five patients who underwent resection of spinal schwannoma in our department between July 2010 and December 2018 and were followed up for more than 1 year were retrospectively analyzed for age, sex, follow-up duration, imaging and surgical data, recurrence, reoperation, and Japanese Orthopaedic Association scores before and 1 year after surgery. Patients with postoperative recurrence or residual tumor regrowth of >10% at the final visit (R+ group) were compared with patients without recurrence or regrowth (R- group). Multivariate logistic regression analysis was performed to analyze concurrent effects of risk factors on recurrence and regrowth.

RESULTS

The 65 patients (mean age 52.4 years at surgery) had schwannomas involving cervical (n = 14), thoracic (n = 25), and lumbar (n = 26) spinal levels. Mean follow-up duration was 58 months. Location was intradural in 65%, extradural in 17%, and both intradural and extradural in 18%. There were 4 recurrences (6.2%), and the mean interval between surgery and recurrence was 18.8 months. Seven patients (10.8%) experienced regrowth. Comparing group R+ (n = 11) and group R- (n = 54), univariate analysis showed significant differences in Sridhar tumor classification, giant tumor (Sridhar classification II, IVb, and V), left-right and cranial-caudal tumor size, largest diameter, operative time, blood loss, subtotal resection, reoperation, fusion surgery, and follow-up duration. Multivariate logistic regression analysis revealed giant tumor (Sridhar classification types II, IVb, and V) as an independent risk factor for recurrence and regrowth.

CONCLUSIONS

This retrospective review of 65 consecutive patients with spinal schwannoma in a single institution demonstrated that 16.9% had recurrence or regrowth, demonstrating that this potential risk should be kept in mind.

Remnant Tumor Margin as Predictive Factor for Its Growth After Incomplete Resection of Cervical Dumbbell-Shaped Schwannomas

Objective

The purpose of our study was to investigate the risk factors of remnant tumor growth after incomplete resection (IR) of cervical dumbbell-shaped schwannomas (DS).

Methods

Twenty-one patients with IR of cervical DS with at least 2 years of follow-up were included and were divided into 2 groups: the remnant tumor growth (G) (n = 10) and no growth (NG) (n = 11) groups. The tumor location in the axial plane according to Toyama classification, the location of the remnant tumor margin, and the tumor growth rate (MIB-1 index) index were compared.

Results

No significant differences in Toyama classification and MIB-1 index were found. Age was significantly higher in the G group (61.4 years vs. 47.6 years; p=0.030), but univariate logistic regression analysis revealed little correlation to the growth (odds ratio [OR], 1.08; 95% confidence interval [CI], 1.001–1.166; p=0.047). Seventeen patients (9 in the G and 8 in the NG group) underwent the posterior one-way approach, and significant differences in the location of the remnant tumor margin were confirmed: within the spinal canal in 1 and 0 case, at the entrance of the intervertebral foramen in 7 and 1 cases, and in the foramen distal from the entrance in 1 and 7 cases, in the G and NG groups, respectively (p=0.007). The proximal margin was identified as a significant predictor of the growth (OR, 56.0; 95% CI, 2.93–1,072; p=0.008).

Conclusion

Remnant tumors with margins distally away from the entrance of the foramen were less likely to grow after IR of cervical DS.

Surgical Management of Giant Thoracic Paraspinal Schwannomas

BACKGROUND

Giant paraspinal thoracic schwannomas (GPTSs) are benign, slow-growing, encapsulated lesions. They can be intracanalicular, span more than 2 vertebral bodies, and/or have a foraminal component with extraspinal extension >2.5 cm. They pose surgical challenges because of the often unfamiliar complex regional anatomy. We report the largest series of GPTSs and discuss regional surgical strategies for tumors in the thoracic spine.

METHODS

We conducted a retrospective review of GPTSs operated at a national spinal referral center between December 2008 and October 2019. Inclusion criteria included World Health Organization grade 1 GPTS. Patient demographics, clinical features, radiology, and histopathology were assessed.

RESULTS

Seventeen patients (12 females, 5 males) had a mean age of 48.1 years (range 21-65 years). Five GPTS (29%) were located at T1-T3, 6 (35%) at T4-6, and 6 (35%) below T6. The mean maximum diameter was 58.5 ± 19.1 mm (range 30-91 mm). Mean volume was 90.9 cm³ (range 19.1-350.6 cm³). Twelve (70%) had a fluorodeoxyglucose positron emission tomography scan showing low (25%) or moderate to high (75%) uptake. Six patients (35%) had preoperative computed tomography-guided biopsy. Surgical approaches included 1) manubriotomy and variations (4/17); 2) high lateral thoracotomy (4/17); 3) posterior parascapular (1/17); 4) standard lateral thoracotomy (3/16); 5) posterior/posterolateral (2/17); and 6) combined posterior and thoracotomy (3/17). All patients had gross total resection and were grade 1 cellular schwannomas. No recurrence at final follow-up (mean 36.1 months, range 8-130 months).

CONCLUSIONS

A number of approaches are available to resect GPST in specific locations in the thoracic spine. Total resection is achievable despite complex regional anatomy, location, and tumor extension but often requires anterior or combined approaches.

Subtotal resection of cervical schwannomas and growth rate of residual tumors

OBJECTIVE

The objective of this study was to elucidate the features and surgical outcomes of cervical schwannomas.

METHODS

The authors retrospectively reviewed the records of 90 patients who underwent surgically treated cervical schwannomas from January 1995 to December 2017, with an emphasis on MRI findings such as tumor location, tumor size, extent of tumor resection, and growth of a residual tumor.

RESULTS

This study included 51 men (56.7%) and 39 women (43.3%) with a mean age of 44.5 years (range 7-77 years). Dumbbell-shaped tumors comprised 62 (68.9%) of 90 cases and gross-total resection (GTR) was achieved in 59 (65.6%) of 90 cases. All nondumbbell tumors (n = 28) underwent GTR. Only 1 case of recurrence in the GTR group showed a gradual increase in size (by 8.9 mm) during the 150-month follow-up period. For the regrowth patients in the subtotal resection group, the mean percentage increase in tumor size was 47.5% ± 33.1% and the mean growth rate was 5.8 ± 4.6 mm/year during the 20.3-month follow-up period. However, the size of residual tumor spontaneously decreased by a mean of 8.3% ± 11.1% during the 48.4-month follow-up period in the nonregrowth group.

CONCLUSIONS

These findings suggested that frequent MRI follow-up examinations are required for residual schwannomas in the cervical spine for at least 2 years, and continuous MRI follow-ups are also required thereafter.

Giant spinal nerve sheath tumours - Surgical challenges: case series and literature review

Background: Giant nerve sheath tumours (GNST) are rare and literature on their management is scant. Spinal GNST present as a surgical challenge due to the involvement of anatomical regions often outside the "comfort zone" of a spinal surgeon. This case series aims to identify challenges in the surgical management of GNSTs. Methods: Retrospective case note review of all spinal GNST cases from 2010 to 2016 managed in Sheffield Teaching Hospitals identified 8 patients, 3 of whom were incidental findings (kept under surveillance) and were excluded. 5 cases were treated surgically. Data collected included patient demographic, presenting symptom(s), radiological data, surgical approach to the tumour and challenges encountered, histopathology report and follow up. Results: Our cohort consisted entirely of females (N = 5) with a mean age of 56.4 years (range 45-70). Imaging studies and histopathological diagnoses confirmed 5 GNSTs (four benign schwannomas and one ganglioneuroma). A Single-stage anterior approach was adopted for three patients while a combined anterior-posterior approach was adopted for the remaining two. In one patient, a posterior approach was initially planned, but this was abandoned and converted to an anterior approach following onset of acute superior vena cava (SVC) syndrome secondary to SVC compression by the giant tumour on prone positioning of the patient. PET imaging of case 3 showed intense tracer uptake consistent with malignancy, however histology confirmed WHO grade 1 Schwannoma. The other three non-operated GNSTs are kept under yearly radiological and clinical surveillance. Conclusions: GNSTs are surgically challenging as they often invade territories that are beyond the comfort zone of one single specialty. A multidisciplinary approach with careful pre-operative surgical planning is recommended. Patients in whom a posterior approach is planned should have a trial of prone positioning pre-operatively. Careful interpretation of FDG-PET imaging is recommended due to the possibility of false positive result.

Spinal Cord Subependymoma Surgery : A Multi-Institutional Experience

OBJECTIVE

A spinal cord subependymoma is an uncommon, indolent, benign spinal cord tumor. It is radiologically similar to a spinal cord ependymoma, but surgical findings and outcomes differ. Gross total resection of the tumor is not always feasible. The present study was done to determine the clinical, radiological and pathological characteristics of spinal cord subependymomas.

METHODS

We retrospectively reviewed the medical records of ten spinal cord subependymoma patients (M : F=4 : 6; median 38 years; range, 21-77) from four institutions.

RESULTS

The most common symptoms were sensory changes and/or pain in eight patients, followed by motor weakness in six. The median duration of symptoms was 9.5 months. Preoperative radiological diagnosis was ependymoma in seven and astrocytoma in three. The tumors were located eccentrically in six and were not enhanced in six. Gross total resection of the tumor was achieved in five patients, whereas subtotal or partial resection was inevitable in the other five patients due to a poor dissection plane. Adjuvant radiotherapy was performed in two patients. Neurological deterioration occurred in two patients; transient weakness in one after subtotal resection and permanent weakness after gross total resection in the other. Recurrence or regrowth of the tumor was not observed during the median 31.5 months follow-up period (range, 8-89).

CONCLUSION

Spinal cord subependymoma should be considered when the tumor is located eccentrically and is not dissected easily from the spinal cord. Considering the rather indolent nature of spinal cord subependymomas, subtotal removal without the risk of neurological deficit is another option.

Spinal Nerves Schwannomas: Experience on 367 Cases-Historic Overview on How Clinical, Radiological, and Surgical Practices Have Changed over a Course of 60 Years

Background

Spinal schwannomas are common benign spinal tumors. Their treatment has significantly evolved over the years, and preserving neurological functions has become one of the main treatment goals together with tumor resection.

Study Design and Aims

Retrospective review focused on clinical assessment, treatment techniques, and outcomes.

Methods

A retrospective study on our surgical series was performed. Clinical and operative data were analyzed. In regard to neurophysiologic monitoring, patients were retrospectively divided into two groups comparing the outcomes before and after introduction of routine intraoperative neurophysiology tests.

Results

From 1951 to 2010, 367 patients overall were treated. Diagnosis was obtained using angiography and/or myelography (pre-CT era), MRI, or CT scan. A posterior spinal approach was used for most patients; complex approaches were adopted for treatment of giant/dumbbell tumors. A trend of neurophysiology monitoring decreasing the rate of post-op neurological deficits was observed but was not statistically significant enough to draft evidence-based conclusions.

Conclusions

Clinical and radiological assessment of spinal schwannomas has markedly changed over the course of 50 years. Diagnostic tools have improved, and detection of recurrence has become way more sensitive. Neurophysiologic monitoring has become a useful intraoperative tool to guide resection and prevent post-op neurological impairment.

Clinical outcomes following resection of giant spinal schwannomas: a case series of 32 patients

OBJECTIVE

The objective of this study was to review clinical outcomes following resection of giant spinal schwannomas.

METHODS

The authors conducted a retrospective review of a case series of patients with giant spinal schwannomas at a tertiary cancer hospital.

RESULTS

Thirty-two patients with giant spinal schwannomas underwent surgery between September 1998 and May 2013. Tumor size ranged from 2.5 cm to 14.6 cm with a median size of 5.8 cm. There were 9 females (28.1%) and 23 males (71.9%), and the median age was 47 years (range 23–83 years). The median follow-up duration was 36.0 months (range 12.2–132.4 months). Three patients (9.4%) experienced recurrence and required further treatment. All recurrences developed following subtotal resection (STR) of cellular or melanotic schwannoma. There were 3 melanotic (9.4%) and 6 cellular (18.8%) schwannomas included in this study. Among these histological variants, a 33.3% recurrence rate was noted. In 1 case of melanotic schwannoma, malignant transformation occurred. No recurrence occurred following gross-total resection (GTR) or when a fibrous capsule remained due to its adherence to functional nerve roots.

CONCLUSIONS

Resection is the treatment of choice for symptomatic or growing giant schwannomas, frequently requiring anterior or combined approaches, with the goals of symptom relief and prevention of recurrence. In this series, tumors that underwent GTR, or where only capsule remained, did not recur. Only melanotic and cellular schwannomas that underwent STR recurred.

Clinical Features and Prognostic Factors of Patients With Nerve Sheath Tumors in the Cervical Spine

STUDY DESIGN

A retrospective study was performed.

OBJECTIVE

The aim of the study was to illustrate the long-term follow-up results and discuss the possible factors that may affect outcomes of patients with cervical spinal nerve sheath tumors (CSNSTs).

SUMMARY OF BACKGROUND DATA

Nerve sheath tumors are the most common neoplasms in the spine, but minimal information was published in the literature, especially when regarding to prognostic factors due to the benign nature. The objective of our study was to present long-term follow-up results and discuss the possible factors that may affect outcomes of patients with CSNSTs.

METHODS

A retrospective analysis of patients with CSNSTs was performed by survival analysis. The local relapse-free survival (LRFS) and overall survival (OS) rates were estimated using the Kaplan-Meier method to identify potential prognostic factors. Factors with P values ≤0.1 were subjected to multivariate analysis by Cox regression analysis. P values ≤0.05 were considered statistically significant.

RESULTS

A total of 169 patients with CSNSTs were included in the study. All patients received surgical treatment. The mean follow-up period was 72.1 months (median 62.0, range 1-158). Local recurrence was detected in 14 patients after surgery in our center, whereas death occurred in 9 patients with a mean follow-up of 27.2 months (median 24, range 1-84). The statistical analyses suggested that resection mode and pathology type were independent prognostic factors for LRFS and OS. In addition, postoperative recurrence was an adverse independent factor to OS.

CONCLUSION

Total resection could significantly improve the LRFS and OS for patients with CSNSTs, whereas malignant CSNST was associated with worse prognosis. Moreover, postoperative recurrence was an adverse independent factor to OS.

LEVEL OF EVIDENCE

4.

Risk Factors for Recurrence of Surgically Treated Conventional Spinal Schwannomas: Analysis of 169 Patients From a Multicenter International Database

STUDY DESIGN

A retrospective analysis of 169 adult patients operated for a conventional spinal schwannoma from the AOSpine Multicenter Primary Spinal Tumors Database.

OBJECTIVE

The aim of this study is to identify risk factors for local recurrence of conventional spinal schwannoma in patients who had surgery.

SUMMARY OF BACKGROUND DATA

Schwannomas account for up to 30% of all adult spinal tumors. Total resection is the gold standard for patients with sensory or motor deficits. Local recurrence is reported to be approximately 5% and usually occurs several years after surgery.

METHODS

Rates and time of local recurrence of spinal schwannoma were quantified. Predictive value of various clinical factors was assessed, including age, gender, tumor size, affected spinal segment, and type of surgery. Descriptive statistics and univariate regression analyses were performed.

RESULTS

Nine (5.32%) out the 169 patients in this study experienced local recurrence approximately 1.7 years postoperatively. Univariate analyses revealed that recurrence tended to occur more often in younger patients (39.33 ± 14.58 versus 47.01 ± 15.29 years) and in the lumbar segment (55.56%), although this did not reach significance [hazard ratio (HR) 0.96, P = 0.127; and P = 0.195, respectively]. Recurrence also arose in the cervical and sacral spine (22.22%, respectively) but not in the thoracic area. Tumors were significantly larger in patients with recurrence (6.97 ± 4.66  cm versus 3.81 ± 3.34  cm), with extent in the cranial caudal direction posing the greatest hazard (HR = 1.321, P = 0.002). The location of the tumor, whether epidural, intradural, or both (P = 0.246), was not significantly related to recurrence. Regarding surgical technique, over 4 times as many patients who underwent intralesional resection experienced a recurrence proportionally to patients who underwent en bloc resection (HR = 4.178, P = 0.033).

CONCLUSION

The pre-operative size of the conventional spinal schwannoma and intralesional resection are the main risk factors for local postoperative recurrence.

LEVEL OF EVIDENCE

3.

Long-term recurrence rates after the removal of spinal meningiomas in relation to Simpson grades

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 Strategies for Cervical Spinal Neurinomas

Cervical spinal neurinomas are benign tumors that arise from nerve roots. Based on their location, these tumors can also take the form of a dumbbell-shaped mass. Treatment strategies for these tumors have raised several controversial issues such as appropriate surgical indications and selection of surgical approaches for cervical dumbbell-shaped spinal neurinomas. In this report, we review previous literature and retrospectively analyze cervical spinal neurinoma cases that have been treated at our hospital. Surgical indications and approaches based on tumor location and severity are discussed in detail. Thus, with advances in neuroimaging and neurophysiological monitoring, we conclude that appropriate surgical approaches and intraoperative surgical manipulations should be chosen on a case-by-case basis.