Schwannoma of the spinal accessory nerve in the cisterna magna.

BACKGROUND: Intracranial schwannoma of the accessory nerve can be divided into two types. One is a jugular foramen type arising from the accessory nerve of the jugular foramen, while the other is an intracisternal type, which arises from the spinal root of the accessory nerve and is separate from the jugular foramen. The latter type is rare, and only 9 cases have been reported previously. CASE DESCRIPTION: A 46-year-old female presented with a large, midline mass lesion in the posterior fossa manifesting as foramen magnum syndrome. Magnetic resonance imaging (MRI) revealed a huge tumor with cystic lesion located in the cisterna magna with extension to the C1 spinal level. The tumor was totally removed by a suboccipital craniectomy and C1 laminectomy. It originated from the spinal root of the right accessory nerve. Temporary slight atrophy of the right sternocleidomastoid muscle was observed, but the patient was free of disease 2 years after treatment. CONCLUSIONS: We report a schwannoma of the spinal accessory nerve in the cisterna magna. The clinical and neuroradiological findings are discussed with a review of the literature. The initial symptoms were variable without loss of function of the cranial nerve, and the tumor tended to grow in the cisterna magna without laterality. Because of the absence of typical neurologic symptoms, early neuroradiological investigation by MRI is recommended for accurate diagnosis of these tumors.