Journal of neurosurgery
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Journal of neurosurgery · May 1987
ReviewVertebrobasilar insufficiency. Part 2. Microsurgical treatment of intracranial vertebrobasilar disease.
Posterior circulation transient ischemic attacks have an associated risk of subsequent infarction of approximately 5% per year. Intracranial vertebrobasilar thrombo-occlusive lesions appear particularly likely to result in repetitive ischemic symptoms and in infarction due to hemodynamic insufficiency. The authors present their experience with 45 patients with symptomatic intracranial vertebrobasilar vascular disease despite maximal medical therapy. The specific operative approaches for intracranial vertebral artery endarterectomy and extracranial to intracranial posterior circulation revascularization procedures are outlined.
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Journal of neurosurgery · May 1987
Monitoring facial EMG responses during microvascular decompression operations for hemifacial spasm.
Facial electromyographic (EMG) responses were monitored intraoperatively in 67 patients with hemifacial spasm who were operated on consecutively by microvascular decompression of the facial nerve near its exit from the brain stem. At the beginning of the operation, electrical stimulation of the temporal or the zygomatic branch of the facial nerve gave rise to a burst of EMG activity (autoexcitation) and spontaneous EMG activity (spasm) that could be recorded from the mentalis muscle in all patients. In some patients, the spontaneous activity and the autoexcitation disappeared after the dura was incised or when the arachnoid was opened, but stimulation of the temporal branch of the facial nerve caused electrically recordable activity in the mentalis muscle (lateral spread) with a latency of about 10 msec that lasted until the facial nerve was decompressed in all but one patient, in whom it disappeared when the arachnoidal membrane was opened. ⋯ Of the 44 patients in whom the lateral spread response disappeared totally, 42 were free from spasm and two had occasional mild spasm at 6 and 13 months, respectively, after the operation. Monitoring of facial EMG responses is now used routinely by the authors during operations to relieve hemifacial spasm, and is performed simultaneously with monitoring of auditory function for the purpose of preserving hearing. The usefulness of monitoring both brain-stem auditory evoked potentials recorded from electrodes placed on the scalp and compound action potentials recorded directly from the eighth cranial nerve is evaluated.