Microsurgical management of non-neurofibromatosis spinal schwannoma

Percutaneous Full Endoscopic Management of Spinal Foraminal Schwannomas: Case Series

BACKGROUND

Schwannoma, a benign peripheral nerve sheath tumor, is perhaps only secondary to degenerative pathology as the most common lesion at neural foramen. The surgical dilemma here is either risking nerve injury because of inadequate exposure or the need for internal fixation because of facet joint sacrifice.

OBJECTIVE

To evaluate the feasibility and safety of management of foraminal schwannomas by percutaneous full-endoscopic technique.

METHODS

A single-center retrospective review was conducted on patients who underwent full-endoscopic resection of neural foraminal schwannomas. Tumors were grouped into either medial type or lateral type based on relevant location to the neural foramen, and respective surgical approaches were adopted. Data including preoperative neurological status, tumor size, surgery time, the extension of resection, and clinical outcomes were collected. The learning curve was plotted as surgical time/tumor size against case number.

RESULTS

A total of 25 patients were treated between May 2015 and March 2022. Gross total resection was achieved in 24 patients, and near-total resection in 1 case, with 1 patient experienced transient voiding difficulty. No tumor recurrence or spinal instability was detected in the short-term follow-up (median follow-up 22 months, range 3 months-6 years). Surgical efficiency improved with the number of cases operated on and remained stable after the initial 10 cases.

CONCLUSION

Percutaneous full-endoscopic technique is a safe and minimally invasive technique for the resection of foraminal schwannomas.

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.

Surgical resection of intradural extramedullary tumors in the atlantoaxial spine via a posterior approach

BACKGROUND

The anatomical features of the atlantoaxial spine increase the difficulty of complete and safe removal of atlantoaxial intradural extramedullary (IDEM) tumors. Studies concerning surgical interventions via a posterior approach are limited.

AIM

To investigate the safety and efficacy of atlantoaxial IDEM tumor resection using a one-stage posterior approach.

METHODS

We retrospectively analyzed clinical databases for one-stage atlantoaxial IDEM tumor resection via a posterior approach between January 2008 and January 2018. The analyzed data included tumor position, histopathological type, pre- and post-operative Japanese Orthopedic Association (JOA) scores and Nurick grades, postoperative complication and recurrence status.

RESULTS

A total of 13 patients who underwent C1-C2 Laminectomy and/or unilateral facetectomy via the posterior approach were enrolled in the study. In all cases reviewed, total tumor resection and concomitant C1-C2 fusion were achieved. The average follow-up was 35.3 ± 6.9 mo (range, 26-49 mo). A statistically significant difference was noted between the preoperative JOA score (11.2 ± 1.1) and the score at the last final follow-up (15.6 ± 1.0) (P < 0.05). A statistically significant difference was noted between the preoperative Nurick grade (2.3 ± 0.9) and that at the last follow-up (1.2 ± 0.4) (P < 0.05). However, no statistically significant difference was noted between the preoperative and last follow-up C1-2 Cobb angle and C2-7 Cobb angle (P > 0.05). No mortalities, severe complications or tumor recurrence were observed during the follow-up period.

CONCLUSION

Total resection of atlantoaxial IDEM tumors is feasible and effective via a posterior approach. Surgical reconstruction should be considered to avoid iatrogenic kyphosis and improve spinal stability and overall clinical outcomes.

Giant schwannoma of thoracic vertebra: A case report

BACKGROUND

It is relatively rare for schwannomas to invade bone, but it is very rare for a large mass to form concurrently in the paravertebral region. Surgical resection is the only effective treatment. Because of the extensive tumor involvement and the many important surrounding structures, the tumor needs to be fully exposed. Most of the tumors are completely removed by posterior combined open-heart surgery to relieve spinal cord compression, restore the stability of the spine and maximize the recovery of nerve and spinal cord function. The main objective of this article is to present a schwannoma that had invaded the T5 and T6 vertebral bodies and formed a large paravertebral mass with simultaneous invasion of the spinal canal and compression of the spinal cord.

CASE SUMMARY

A 40-year-old female suffered from intermittent chest and back pain for 8 years. Computed tomography and magnetic resonance imaging scans showed a paravertebral tumor of approximately 86 mm × 109 mm × 116 mm, where the adjacent T5 and T6 vertebral bodies were invaded by the tumor, the right intervertebral foramen was enlarged, and the tumor had invaded the spinal canal to compress the thoracic medulla. The preoperative puncture biopsy diagnosed a benign schwannoma. Complete resection of the tumor was achieved by a two-step operation. In the first step, the thoracic surgeon adopted a lateral approach to separate the thoracic tumor from the lung. In the second step, a spine surgeon performed a posterior midline approach to dissect the tumor from the vertebral junction through removal of the tumor from the posterior side and further resection of the entire T5 and T6 vertebral bodies. The large bone defect was reconstructed with titanium mesh, and the posterior root arch was nail-fixed. Due to the large amount of intraoperative bleeding, we performed tumor angioembolization before surgery to reduce and avoid large intraoperative bleeding. The postoperative diagnosis of benign schwannoma was confirmed by histochemical examination. There was no sign of tumor recurrence or spinal instability during the 2-year follow-up.

CONCLUSION

Giant schwannoma is uncommon. In this case, a complete surgical resection of a giant thoracic nerve sheath tumor that invaded part of the vertebral body and compressed the spinal cord was safe and effective.

Single root multiple spinal schwannomas: Case report, treatment strategy and review of literature

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Schwannomatosis is defined as multiple schwannomas without presence of neurofibromatosis and this is a relatively rare pathology.

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In vast majority of cases the schwannomas grew from different nerve roots.

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We present the case of a patient with six schwannomas of the cauda equina that grew from a single spinal root as well as discuss the treatment strategy.

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Multiple spinal cord schwannomas that are growing along the same part of the vertebral column can be safely removed by one side hemilaminectomy using a high-speed diamond drill with preservation of the integrity of the muscles and ligaments on the opposite side and thus maintain spinal stability.

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Neuromonitoring is mandatory for the surgical procedure to allow successful results and to prevent any neurological damage.

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The 30 degree endoscope can be a good tool for visual exploration of the spinal canal.

Introduction

Schwannomatosis is defined as multiple schwannomas without presence of neurofibromatosis and is a rare pathology. In vast majority of cases the schwannomas grow from different nerve roots or peripheral nerves.

Presentation of case

A 52-year-old woman presented with multiple intradural schwannomas arranged in a chain along the spinal canal causing significant compression. The lesions were successfully removed using a left side en-bloc hemilaminectomy technique in order to preserve maximal stability of the posterior column. Back and leg pain resolved completely. Tendon reflexes returned to normal shortly. There was decreased pain sensation in the distribution of the left L3 spinal root.

Discussion

The traditional surgical strategy for posterior approach by laminectomy or laminotomy is sometimes complicated with instability or deformation of the vertebral column that requires surgical stabilization. We performed a one side en-bloc hemilaminectomy thus maintaining the integrity of the muscles and ligaments on the opposite side and preserving maximal stability of the vertebral column. Densely adherent tumors required careful sharp dissection and separation under neurosurgical monitoring and stimulation for recognition and preservation of spinal roots. An additional tumor was discovered by exploration of the spinal canal using an endoscope.

Conclusion

Multiple spinal cord schwannomas that are growing along the same part of the vertebral column can be safely removed by one-sided hemilaminectomy with preservation of the integrity of the muscles and ligaments on the opposite side and thus maintain spinal stability. The 30° endoscope can be a good tool for visual exploration of the spinal canal.

Non-Syndromic Spinal Schwannomas: A Novel Classification

Schwannomas are the most frequent primary tumors of the spine with an incidence of 0.3-0.5/100,000 person per year. Current treatment for non-syndromic spinal schwannomas is total resection of the tumor with preservation of neurovascular structures. This study aims to report neurologic and radiologic outcome following treatment of non-syndromic spinal schwannomas along with a novel tumor classification used in our clinic. A retrospective case series was carried out with a patient sample of 82 male and female patients with non-syndromic spinal schwannomas. All patient data were retrospectively collected from the hospital records. As a routine procedure, after admittance and primary evaluation, patients' tumors were classified using CT or MRI in accordance with our proposed classification method, which employs a dual designation method with tree groups (A, B, and C) for tumor volume and four types (I, II, III, and IV) for tumor localization. Subsequent resection surgery was followed by neurological assessments and follow up at 45th, 180th, and 360th postoperative day. Along with Karnofsky performance status scale, pain, sensory deficits, and motor weakness were scored to assess neurologic recovery. Our finding indicates that patients with different tumor types significantly differ in their neurological scores and show consistent but differential neurological recovery at early and late time points postsurgery. Complications during and postsurgery were minimal, occurring only in two patients. Our findings further reinforce the established safety of total resection operations and indicate that our proposed classification is a simple, effective tool that has proven helpful in preoperative planning and avoiding unnecessary surgical approaches.

Minimally invasive removal of lumbar intradural extramedullary lesions using the interlaminar approach

OBJECT Posterior midline laminectomy or hemilaminectomy has been successfully applied as the standard microsurgical technique for the treatment of spinal intradural pathologies. However, the associated risks of postoperative spinal instability increase the need for subsequent fusion surgery to prevent potential long-term spinal deformity. Continuous efforts have been made to minimize injuries to the surrounding tissue resulting from surgical manipulations. The authors report here their experiences with a novel minimally invasive surgical approach, namely the interlaminar approach, for the treatment of lumbar intraspinal tumors. METHODS A retrospective review was conducted of patients at the Second Affiliated Hospital of Zhejiang University School of Medicine who underwent minimally invasive resection of lumbar intradural-extramedullary tumors. By using an operative microscope, in addition to an endoscope when necessary, the authors were able to treat all patients with a unilateral, paramedian, bone-sparing interlaminar technique. Data including preoperative neurological status, tumor location, size, pathological diagnosis, extension of resections, intraoperative blood loss, length of hospital stay, and clinical outcomes were obtained through clinical and radiological examinations. RESULTS Eighteen patients diagnosed with lumbar intradural-extramedullary tumors were treated from October 2013 to March 2015 by this interlaminar technique. A microscope was used in 15 cases, and the remaining 3 cases were treated using a microscope as well as an endoscope. There were 14 schwannomas, 2 ependymomas, 1 epidermoid cyst, and 1 enterogenous cyst. Postoperative radiological follow-up revealed complete removal of all the lesions and no signs of bone defects in the lamina. At clinical follow-up, 14 of the 18 patients had less pain, and patients' motor/sensory functions improved or remained normal in all cases except 1. CONClUSIONS When meeting certain selection criteria, intradural-extramedullary lumbar tumors, especially schwannomas, can be completely and safely resected through a less-invasive interlaminar approach using a microscope, or a microscope in addition to an endoscope when necessary. This approach was advantageous because it caused even less bone destruction, resulting in better postoperative spinal stability, no need for facetectomy and fusion, and quicker functional recovery for the patients. Individualized surgical planning according to preoperative radiological findings is key to a successful microsurgical resection of these lesions through the interlaminar space.

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.