Surgical strategies for removal of intra- and extraforaminal dumbbell-shaped schwannomas in the subaxial cervical spine.

Abstract

Spinal dumbbell-shaped schwannoma is common neoplasm, usually occurring in the cervical spine. Posterior or anterolateral approaches are frequently used to remove this benign tumor. We analyzed how much amount of tumor could be possible to be totally removed with posterior approach. Surgery was performed on 41 cases of cervical, dumbbell-shaped subaxial schwannomas with both intra- and extraforaminal involvement. The same surgeon performed all the procedures. Mean follow-up was 42.5months (24-108months). A combined anterolateral and posterior approach was used if the extraforaminal tumor was larger than 10mm. A posterior approach and unilateral facet removal were used if it was smaller than 10mm. We performed MRI and serial dynamic X-rays for postoperative 2years. We used the posterior approach with facetectomy in 35 cases and the combined approach in six. Complete removal was achieved with the combined approach in all six, and with the posterior approach in 28 of 35 cases. With the posterior approach, the extraforaminal dimension of totally resected tumors ranged from 3 to 5.4mm. Subtotal resection was limited to extraforaminal tumors larger than 5.7mm. On follow-up, instability on dynamic X-ray was not observed before 24months in any patient after unilateral facetectomy. Total removal of intra- and extraforaminal cervical subaxial schwannomas could be possible using a posterior approach with facet removal if the size of extraforaminal tumor was less than 5.4mm.