Microvascular Decompression for Hemifacial Spasm Associated with Bilateral Vertebral Artery Compression

Abstract

Microvascular decompression (MVD) has been established as an effective treatment for hemifacial spasm (HFS). However, replacement of bilateral vertebral arteries (VAs) from the root exit zone (REZ) is difficult and requires special techniques. Reports of HFS cases associated with bilateral VA compression are quite rare. This study investigated the characteristics of these arteries and methods for safe and definite decompression. Among 131 patients who underwent MVD for HFS, 33 patients (25.2%) had associated VA compression; 4 patients (3.1%) had bilateral VA compression. Sufficient dissection of the arachnoid membrane allowed good visualization around the REZ, and the dolichoectatic VAs were successfully transposed and fixed to the nearby dura mater in 3 cases. The offending arteries were bilateral VAs plus the posterior inferior cerebellar artery in 2 cases, bilateral VAs plus the anterior inferior cerebellar artery-posterior inferior cerebellar artery in 1 case, and bilateral VAs in 1 case. The contralateral VA of the symptomatic side was more ectatic, dolichoectatic, and tougher than the ipsilateral VA in 3 patients and was difficult to remove. In 3 patients treated with the transposition method, complete resolution of spasm was experienced immediately after surgery. Minimal residual spasm occurred in 1 patient treated with the interposition method. Transient facial palsy developed in 1 case, and moderate hearing loss developed in another case. HFS caused by bilateral VA compression is rare; however, replacement of VAs from the REZ is not easy because such VAs are invariably dolichoectatic and tough. Treatment of such cases requires special techniques.