[Microvascular decompression for hemifacial spasm induced by vertebral artery dissecting aneurysm: one case report].

A 61-year-old female presented with 4 years history of left-sided hemifacial spasm. Head MRI and angiography indicated left vertebral artery dissecting aneurysm which compressed ipsilateral cranial nerves Ⅶ and Ⅷ. Microvascular decompression was performed. The dissecting aneurysm was pushed apart and the distal part of the parent artery was adhered to the dura on the petrosum. The compressed nerves were totally decompressed. The symptom of facial spasm was completely resolved immediately after surgery and did not recur during 6 months of follow up.