Micro vascular Decompression of Cranial Nerves, Particularly of the 7th Cranial Nerve

Fifty-three patients with hemifacial spasm, six patients with trigeminal neuralgia and five patients with unilateral tinnitus were treated by a “microvascular decompression” method and follow-up results for more than one year were evaluated. Follow-up operative results of 44 patients with hemifacial spasm were : 1) excellent—24, 2) good—12, 3) fair—7 and 4) poor—1. The operative results of hemifacial spasm were evaluated according to Jannetta's classification17) combined with the degree of postoperative hearing reduction. Reduction of hearing acuity occurred in nine out of 53 patients. No recurrence of hemifacial spasm was encountered during follow-up period. It was interesting enough that the ipsilateral facial paresis which existed preoperatively gradually improved after decompressive surgery for hemifacial spasm. Eight out of 10 patients who developed facial paresis without having previous traumatizing surgical treatment and six out of 13 patients who had undergone previous peripheral surgical treatment for hemifacial spasm gradually improved after this decompressive surgery. All six patients with trigeminal neuralgia were completely cured and they noticed no sensory changes on the affected side of the face postoperatively. Four out of five patients with tinnitus were improved by the surgery. The most characteristic forms of compressing arteries were that the arteries crossdistorted the cranial nerves usually at their exit zones from the brain-stem and the arteries were angled and sclerotic focally at the compressing sites. Vertebral angiographic studies provided a key to solve the problem of why these arteries were sclerotic at the angular part and why hemifacial spasm affected one side of the face. Although the etiology of these hyperactive dysfunctions of the cranial nerves is still controversial, vascular compression-distortion seems very likely to be responsible for these syndromes. The “microvascular decompression” of cranial nerves is a refined and nontraumatic technique which seems to promise a stable and permanent cure of the hyperdysfunction of cranial nerves.