Spinal accessory nerve meningioma at the foramen magnum with medullar compression: a case report and literature review.

BACKGROUND: Meningiomas that arise from the cranial nerve are rare. We present a case with an intradural extramedullary tumor at the foramen magnum originating from the spinal accessory nerve. CASE DESCRIPTION: The patient was a 69-year-old woman with dizziness and pain in the bilateral shoulder for 2 years. Neurologic examination revealed spinal accessory nerve palsy (difficult in raising the shoulder, deficit of 3/5) on the left side without further deficits. Magnetic resonance imaging showed medullar compression because of a left intradural extramedullary foramen magnum lesion dorsolateral to the medulla. Surgical exposure via a midline suboccipital approach with C1 laminectomy revealed that the lesion arises from the left accessory nerve without dural attachment. The tumor was resected without injury to the spinal accessory nerve, and histologic examination revealed that it was a meningothelial meningioma. The spinal accessory nerve palsy improved to 4 of 5 after 3 months after surgery. CONCLUSIONS: To our knowledge, this is the first report of an accessory nerve meningioma at the foramen magnum in which the spinal accessory nerve palsy appeared before operation and improved after tumor resection.