[Ultrastructural changes in the facial nerve root in patients with hemifacial spasm]

Ten facial nerve root specimens obtained from patients with hemifacial spasm were observed under the electronmicroscopy. The axons showed a particular degeneration. Axonal mitochondria and smooth endoplasm showed irregular vacuolization. In severe cases, the mitochondria and smooth endoplasm disappeared. The myelin sheath showed irregular vacuolization, replication, convolution and extensive segmental demyelination. Schwann cells were apparently in a state of degeneration. These changes were not seen in the normal subject. The causes and mechanism of the hemifacial spasm were discussed.