We have operated on nine patients with a prepontine epidermoid extending to the bilateral cistern or the unilateral middle fossa using the anterior transpetrosal approach since 1986. The preoperative symptoms were unilateral trigeminal neuralgia, hearing disturbance, gait disturbance, double vision, facial hypesthesia, hemifacial spasm, and dysphagia. The most common neurological sign was unilateral trigeminal nerve disturbance. In two patients with useful hearing preoperatively lost, the labyrinth and mastoid air cells as well as the petrous apex were resected to extend the surgical field. Tumors were to tally removed, except for capsules that were tightly adhered to the brain stem, cranial nerve, and vessels. The trigeminal neuralgia, hemifacial spasm, and dysphagia disappeared, but double vision improved only one out of three cases, and facial hypesthesia was unchanged in all cases. There were no postoperative deaths. New abducens palsy appeared in four eases and cerebrospinal fluid (CSF) leakage appeared in three cases postoperatively, but later these symptoms disappeared. In one case, postoperative chemical meningitis developed, and a ventricular shunt was required later to treat hydrocephalus. Postoperative follow-up, an average of 5.7 years, did not show any increases in any of the tumors. Based on our experience, we conclude that the anterior transpetrosal approach is more useful than the retromastoid suboccipital suboccipital approach to resect the epidermoid located mainly in the prepontine cistern.
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