Hydrocephalus after Gamma Knife Radiosurgery for Schwannoma.

OBJECTIVE: Gamma Knife radiosurgery (GKRS) has been established as an effective and safe treatment for intracranial Schwannoma. However, communicating hydrocephalus can occur after GKRS. The risk factors of this disorder are not yet fully understood. The objective of the study was to assess potential risk factors for hydrocephalus after GKRS. METHODS: We retrospectively reviewed the medical radiosurgical records of 92 patients who underwent GKRS to treat intracranial Schwannoma and developed communicating hydrocephalus. The following parameters were analyzed as potential risk factors for hydrocephalus after GKRS: age, sex, target volume, irradiation dose, prior tumor resection, treatment technique, tumor enhancement pattern, and protein level of cerebrospinal fluid (CSF) after GKRS. RESULTS: Of the 92 patients, eight of them developed communicating hydrocephalus. Target volume and tumor enhancement pattern, and protein level of CSF ware associated with the development of hydrocephalus. CONCLUSION: In particular, patients with intracranial Schwannomas with large tumor size, ring enhancement patterns, and high protein level of CSF should be carefully observed.

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.