Involved Small Arteries in Patients Who Underwent Microvascular Decompression for Hemifacial Spasm.

BACKGROUND: Microvascular decompression (MVD) has become widely accepted as first-line therapy for hemifacial spasm. However, not all patients are candidates for the procedure, and some surgeons ignore arterioles that represent the actual underlying cause of the condition. The aim of this study was to address the role of involved arterioles in management of MVD in patients with hemifacial spasm.

METHODS: Data were collected from 765 consecutive patients who underwent MVD from January 2009 to August 2010 in our hospital. Electromyographic abnormal muscle response and Z-L response were used to identify the involved arterioles. All patients were followed for 25-35 months.

RESULTS: Compression by the involved arterioles was identified in 20 patients. The most commonly involved arteriole was a branch of the anterior inferior cerebellar artery, followed by the posterior inferior cerebellar artery. During follow-up, effective outcomes were achieved in 93.6% of patients with involved arterioles. There was no MVD-related mortality.

CONCLUSIONS: The main reason for failed MVD is that the involved offending vessel is not correctly identified. Intraoperative abnormal muscle response and Z-L response are good supplementary measures to identify involved arterioles. In addition, not isolating or coagulating the involved arterioles increases the risk associated with the operation.