Comparative analysis of MRI features and surgical outcomes between intramedullary and extramedullary schwannomas in the spinal cord.

Abstract

A retrospective comparative study. To clarify the distinctive magnetic resonance imaging (MRI) features and surgical outcomes of intramedullary schwannoma (IMS) compared to extramedullary schwannoma (EMS) in the spinal cord. Hospital in Tokyo, Japan. 19 cases each of IMS and EMS were matched by propensity score from a cohort of spinal cord tumor patients treated between 2008 and 2022. Preoperative MRI images were meticulously analyzed for general values and distinctive features at the tumor-spinal cord interface. Surgical outcomes were assessed based on neurological function, visual analogue scale (VAS), and recurrence rates. IMS and EMS exhibited similar MRI intensity patterns on T1- and T2-weighted images, but differed significantly in features surrounding the tumor, such as rough boarder (IMS: 78.9%, EMS: 5.3%, P value < 0.001) and peritumoral edema (IMS: 57.9%, EMS: 10.5%, P value = 0.005). Postoperatively, IMS cases showed substantial neurological improvement, with no recurrences following gross total resection (GTR). However, residual pain at the segmental level persisted more commonly in IMS compared to EMS (postoperative VAS, IMS: 45.0 ± 34.3, EMS: 19.7 ± 26.8, P value = 0.017). The distinct MRI features identified, particularly the observation of the border with the spinal cord, offer valuable insights for differentiating IMS from EMS preoperatively. Although IMS results in improved neurological function with no recurrence following GTR, attention must be given to residual pain.