A case of intracranial hypoglossal neurinoma

: A case of intracranial hypoglossal neurinoma is reported. A 32-year-old man with a history of unsteady gait and headache for one and a half years was admitted to our hospital on September 23, 1983. Neurological findings on admission were nystagmus toward the left, left IXth and Xth cranial nerve paresis, left cerebellar signs, paresthesia of the left upper and lower extremities on neck flexion, and left pyramidal signs. Atrophy or fasciculation of the tongue was not noted. Computed tomography demonstrated a large isodensity and partially low density mass in the posterior fossa which was markedly enhanced and sharply margined with contrast medium. The tumor extended 45 mm over the edge of the foramen magnum. The maximum size was 45 mm X 40 mm. The coronal and sagittal reconstruction CT scan clearly demonstrated the attachment and extension of the tumor. Enlargement of the hypoglossal canal was clarified by changing the window level, window width and using 2 mm slice CT scan. Anterior-posterior x-ray view of the skull tomography showed enlargement of the hypoglossal canal, as indicated by the CT scan. The left hypoglossal canal was 7 mm and right was 3 mm in diameter. Vertebral angiography demonstrated that the tumor was located in the left posterior fossa, but no tumor stain appeared. This patient did not have XIIth cranial nerve palsy, but the neuroradiological findings strongly suggested a hypoglossal neurinoma, especially the findings of the CT scan and the anterior-posterior x-ray view of the skull tomography. On October 5, suboccipital craniotomy with Cl laminectomy was performed in prone position.(ABSTRACT TRUNCATED AT 250 WORDS)