[Disappearance of hemifacial spasm following spinal drainage: a case report].

This report is concerned with a case of right hemifacial spasm (HFS) occurring in a 65-year-old woman, who incidentally had a left internal carotid-ophthalmic artery aneurysm. The aneurysm was successfully treated by clipping its neck. However, spinal drainage had to be performed postoperatively in order to prevent possible cerebrospinal fluid (CSF) rhinorrhea, as the roof of the sphenoid sinus was accidentally opened during the aneurysm surgery. Liquorrhea was observed and stopped on the 5th postoperative day. The drain was then removed only to be reset because CSF rhinorrhea recurred 8 days later, when the HFS began to subside. When the spinal drain was finally removed 9 days later, the HFS was scarcely seen. The HFS was thought to be due to the compression of the right facial nerve by the ipsilateral AICA. The draining of the CSF might have changed the amount and flow of the liquor and consequently the positional relationship among the facial nerve, the AICA and the arachnoid membrane, resulting in neurovascular decompression.