Hemifacial spasm

✓ Patients with hemifacial spasm were treated by three different surgical procedures: 1) partial sectioning of the facial nerve just distal to the stylomastoid foramen; 2) selective neurectomy of facial nerve branches; and 3) microvascular decompression. A retromastoid craniectomy with microvascular decompression was most effective in relieving hemifacial spasm and synkinesis. In a postmorten examination on one patient, microscopic examination of the facial nerve, which was compressed by an arterial loop of the posterior inferior cerebellar artery at the cerebellopontine angle, revealed fascicular demyelination in the nerve root. On the basis of surgical treatment, electromyography, and neuropathological findings, the authors conclude that compression of the facial nerve root exit zone by vascular structures is the main cause of hemifacial spasm and synkinesis.