Department of Neurosurg Sino-Japanese Friendship Hospital. Zuo Huan Zong A microsurgical vascular decompression technique through the posterior cranial fossa with no section of nerve -was carried out in the treatment of 7 cases of trigeminal neuralgia and 5 cases of hemifacial spasm. At operation it was found that in the trigeminal neuralgia patient

the nerve root of the trigeminal at the exit zone was compressed by directly adjacent arteriole in 6 cases and by the petrosal vein in the remaining case. In the hemifacial spasm patients similar compression of the facial nerve root at the exit zone was observed in 4 cases and in the remaining case no evidence of compression was demonstrated. Postoperatively all seven patients of trigeminal neuralgia were immdiately relieved of their neuralgia symptoms. The 4 patients of hemifacial spasm with demonstrable nerve root compression clearly showed a symptomatic remission and the case showing no compression remained unrelieved.The present report apparently indicates that vascular compression is an important cause of trigeminal neuralgia and hemifacial spasm. The immediate effect of microsurgical vascular decompression is excellent. Remote result await further observation.