Thoracic subpial intramedullary schwannoma involving a ventral nerve root: A case report and review of the literature

Background: Subpial intramedullary schwannoma of the spine is a rare tumor. A few case reports have revealed that the tumor originates from around the ventral nerve exit zone, with only one case confirming involvement of the ventral root. Case Description: A 72-year-old female with a 10-month history of Brown-Séquard-type monoparesis is described. On neurological examination, the left leg motor function was grade 3 or 4/5, and dysthesia with low pinprick sensation at the right side below the T8 and T9 dermatome was identified. There were no signs of multiple neurofibromatosis. Magnetic resonance imaging demonstrated a well-demarcated round mass with high enhancement and moderate peritumoral edema, but no combined syrinx. The mass (1.5 × 1 × 1.5 cm) was located at the anterior part of the spinal canal on the left of the midline of the T8 and T9 space. A left-sided unilateral approach was performed with osteoplastic laminotomy of T8 and T9 vertebrae, and radical removal of a subpial tumor was achieved. Pathological examination revealed subpial intramedullary schwannoma. The patient improved postoperatively and at discharge was able to walk without any support. Conclusion: The authors emphasize that the differential diagnosis of intramedullary schwannoma should be included when peritumoral edema is moderately present to provide appropriate preoperative preparations, even if a tumor is seemingly located in the intradural extramedullary space.