Background: Meningiomas arising from cranial nerves with no dural attachment are exceedingly rare. The authors present a patient with bilateral meningiomatous lesions originating symmetrically from both spinal accessory nerves.
Case report: A 61-year old woman presented with a one-year history of spinal ataxia and minimal left-sided motor impairment. Magnetic resonance imaging demonstrated two extrinsic lesions dorsolaterally of the medulla. Surgical exposure via a midline suboccipital approach with C1 laminectomy revealed the lesions arising from the spinal accessory nerves and in direct contact with the vertebral arteries. Histological investigation showed hypocellular fibrous lesions with proliferating meningothelial cells, psammoma bodies and immunoreactivity for vimentin, S-100 protein and epithelial membrane antigen.
Interpretation: To the authors' knowledge this is the first report of intradural tumours of the spinal accessory nerves not derived from Schwann cells and the first report of bilateral intracranial meningiomatous lesions without dural attachment.