Monitoring auditory nerve potentials during operations in the cerebellopontine angle.

Direct monitoring of auditory nerve potentials was performed in 19 patients undergoing retromastoid craniectomy and microvascular decompression of cranial nerves. In addition, brain stem auditory evoked potentials (BSEPs) were monitored in these patients. No patient suffered significant hearing loss. Direct monitoring of auditory nerve potentials complements the recording of BSEPs because the auditory nerve potentials can be visualized without averaging many responses. Therefore the effect of any intraoperative manipulation that is harmful to the auditory nerve can be detected instantaneously.

Microvascular decompression for trigeminal neuralgia in patients with multiple sclerosis.

BACKGROUND: Microvascular decompression (MVD) of the trigeminal nerve is a well-established procedure for the treatment of idiopathic trigeminal neuralgia. Multiple sclerosis (MS) has long been considered a contraindication for this procedure, due to the known polycentric nature of the disease. Medical treatment followed by percutaneous procedures provide relief for the great majority of these patients. There exists a small subgroup of patients with trigeminal neuralgia who are diagnosed with MS only after a microvascular decompression procedure has been performed. Furthermore, management of the patient with known MS whose pain continues to recur, despite maximal medical therapy and multiple percutaneous procedures, can be exceedingly difficult. METHODS: Five patients with MS, three who had undergone multiple unsuccessful percutaneous procedures and two in whom the diagnosis of MS had not been established, underwent exploration of the cerebellopontine angle. Three patients underwent MVD alone, and two (both with known MS) underwent MVD and partial section of the trigeminal nerve. RESULTS: Patients who underwent microvascular decompression alone did not have satisfactory relief of pain. Patients who underwent partial sectioning of the nerve did better. CONCLUSIONS: Patients with MS and symptoms of typical trigeminal neuralgia may benefit from exploration of the cerebellopontine angle and partial sectioning of the nerve. MVD alone fails to provide adequate or reliable relief of pain.

Paradoxical effects of interferon on reactivation of oral infection with herpes simplex virus after microvascular decompression for trigeminal neuralgia.

Fifty-five patients undergoing microvascular decompression for trigeminal neuralgia were divided into three groups in a two-stage placebo-controlled study. All groups received two injections a day for five days beginning the day before surgery. Twenty-one patients received 10 placebo injections, 11 in the presurgical treatment group received three injections of 3.5 X 10(4) units of leukocyte interferon/kg before surgery, and 23 in the postsurgical treatment group received seven injections after surgery. The remaining injections in the two treatment groups were placebos. In the first stage, with 30 patients, 91% of the presurgical treatment group had reactivated oral herpesvirus infections (manifested by herpetic lesions and/or oral viral shedding) significantly more often than did concurrent controls (P less than .05). In the second stage, only the postsurgical treatment and placebo groups were studied, with no difference in reactivation of herpesvirus infection between the postsurgical treatment and placebo groups. Thus presurgical treatment with interferon alone may actually precipitate and accentuate herpesvirus infection.