Hypoglossal Neurinoma without Preoperative Hypoglossal Nerve Palsy - Report of 2 Cases -

Intracranial hypoglossal neurinomas are rare and only about fifty cases have been reported worldwidely. They usually present with hypoglossal nerve palsy preoperatively. The authors experienced, however, two cases of intracranial hypoglossal neurinomas without preoperative hypoglossal nerve palsy. One patient was operated using transcondylar retrosigmoid approach with C1 laminectomy and the other using midline suboccipital craniectomy with C1 laminectomy. Postoperatively hypoglossal nerve palsy was developed in both cases. Absence of preoperative hypoglossal palsy seemed to be related to somewhat different growth pattern in these two cases. When the tumor shows typical radiological findings of hypoglossal neurinoma, it must be included in differential diagnosis despite absence of preoperative hypoglossal nerve palsy.

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.

Intracranial Hypoglossal Neurinoma: A Case Report

Hypoglossal neurinoma is vary rare cranial base neoplasm. With the recent advances in the neuroimaging and surgical technique, radical surgical resection is amenable. A case of hypoglossal neurinoma which is located ventral to the medulla is reported. The patient was presented with right hypoglossal nerve palsy, glossal hemiatrophy, and decreased gag reflex on the right side. Magnetic resonance imaging(MRI) revealed an ovoid mass ventral to the medulla with enlarged hypoglossal canal. Because of the ventral location of the mass, far lateral transcondylar approach was selected to minimize the postoperative morbidity. Radical total resection was achieved. This report describes that far lateral transcondylar approach is better than conventional suboccipital approach in regards to satisfactory exposure of the hypoglossal canal and prevention of excessive retraction of the neuraxis.

Dumbbell-Shaped Hypoglossal Neurinoma: Case Report and One-stage Operation

A case of dumbbell-shaped hypoglossal neurinoma is reported. Neurinomas of the hypoglossal nerve are very rare, only 35 cases reported. Of these cases, most are intracranial and only 7 were dumbbell-shaped with both intracranial and extracranial components. The clinical feature of the patient was marked ipsilateral atrophy of the tongue. Magnetic resonance imaging should be included in the examination of tumors, and great aids in planning the radical removal of the tumor. In this one-stage operation which was modified lateral inferior suboccipital craniectomy, the most important aspect was removal of the posterior wall of anterior condylar canal and lateral mass of C1. This approach requires a thorough understanding of microsurgical anatomy of the region of foramen magnum. Patient's postoperative course was uneventful. The literatures concerning this lesion were reviewed.