AB007. Intramedullary schwannoma: a rare case report

Background: Intramedullary schwannomas are a rare case, accounting for only 0.3% of all intraspinal neoplasms and 1.1% of spinal schwannomas. These tumors have most often been reported to involve a single lesion affecting the cervical spinal cord (63%), the thoracic spinal cord (26%), and the lumbar spinal cord (11%). Here we report a very rare case thoracic intramedullary schwannoma.

Case Description: A 24-year-old female patient was admitted with gradual onset weakness of both lower limbs for last 2 years with retention of urine. Neurological examination revealed the motor strengths on both legs were 2. There was a sensibility dissociation below Th8 dermatomal level. Magnetic resonance imaging shows an ill-demarcated intramedullary lesion extending from Th8 to Th9 accompanied by spinal cord edema along Th4 to Th11. The surgery was performed with standard posterior middle approach. Laminectomy decompression was performed and dura opened in the midline. Infiltrative nature of the mass made the total resection impossible. Histopathological result followed by immunohistochemistry confirmed the diagnosis of schwannoma. In the postoperative follow-up, the motor strengths of both legs are absent and no clinical improvement at all until now. Prior to surgery, intramedullary schwannoma is often misdiagnosed as other types of tumour, including ependymoma, astrocytoma and hemangioblastoma, due to its atypical imaging appearance and low incidence. Surgery for spinal intramedullary tumors remains one of the major challenges for surgeons, due to their relative infrequency, and surgical difficulty technique. Worse preoperative McCormick Scale, thoracic tumor location, partial resection, and lack of availability of intraoperative neurophysiology monitoring (IONM) were significant factors for poor prognosis.

Conclusions: Intramedullary schwannomas are slow-growing rare tumors and should be considered as one of the differential diagnoses for the intramedullary spinal lesions. Magnetic resonance imaging may be helpful for diagnosis however clear distinction cannot be made between the intramedullary spinal lesions. Total surgical resection is the treatment choice for this patient but infiltrative lesions cannot be resected completely for which radiotherapy has been suggested.

Keywords: Intramedullary schwannomas; McCormick Scale; laminectomy; case report