A Huge Posterior Fossa Arachnoid Cyst with Cervicothoracic Syringomyelia

The authors report a surgically treated patient with very unusual combination of a giant posterior fossa cyst in cerebellopontine area, Chiari I malformation and syringomyelia in cervico-thoracic area. Ventricles were not dilated. He complained weakness and clumsiness on the right upper extremity. His symptom was attributable to the syringomyelia of cervical spinal cord. The authors managed this patient by removing the arachnoid cyst and cystoperitoneal shunt on the assumption that this cyst has an influence on the formation of Chiari malformation and syringomyelia. After operation there was marked improvement in the motor power in the arm, and a follow-up MRI one month later showed a disappearance of syringomyelia. The authors believe that this very unusual condition is of interest in making the pathogenesis of syringomyelia clear.

Modified Transcondylar Approach for a Case of Hypoglossal Neurinoma: Technique

Hypoglossal neurinomas are very rare and those which simultaneously involve the intracranial and extracranial portions are extremely unusual. Using the modified transcondylar approach, the authors successfully removed a dumbbell-shaped hypoglossal neurinoma at the intracranial portion and extending to the anterior upper portion of the axis through the hypoglossal canal. After dividing the cervical musculatures into layers, the vertebral artery was mobilized by opening the foramen transversarium and removing the postero-lateral part of the right occipital condyle, the lateral mass of the atlas and the mastoid tip by means of a small lateral suboccipital craniotomy. This approach offers a wide surgical field and a direct approach to the skull base and upper anterior cervical spine. After total removal of the hypoglossal neurinoma, a very simple supplementary autogenous bone graft was performed between the occipital bone and the lateral mass of the atlas, using the corticocancellous bone fixed with small screws. Postoperatively, the tumor was removed totally and there was no limitation on the cervical rotatory movement. A review of cases of hypoglossal neurinomas and the surgical approaches employed is included in this paper.