The role of vein in microvascular decompression for hemifacial spasm: a clinical analysis of 15 cases

Objectives: The objective of this study is to investigate the clinical characteristics, intraoperative findings, complications, and outcomes in these patients with hemifacial spasm (HFS) caused by venous compression. Methods: We analyzed 15 patients who underwent microvascular decompression (MVD) for HFS caused by venous compression performed at the University of Pittsburgh Medical Center between 1 January 2000 and 31 December 2007. Thirteen of 15 patients underwent repeat MVD, and two patients underwent their first MVD. Clinical data were collected to verify vein as real offending vessel for all of 15 patients with HFS. The mean follow-up period was 4.13 years (range: 1.29-6.76 years). Results: Thirteen patients with repeat MVDs had vein as the offending vessel, such as series of small venule, small veins, and dilated venous stump. The remaining two patients who underwent the first MVD had vein as the only offending vessel. In the first MVD for 13 patients, lateral spread response (LSR) disappeared in five patients (38.5%). In the repeat MVD for these 13 patients, LSR disappeared after the vein was decompressed completely in nine patients (69.2%). An excellent surgical outcome was observed in all the 11 patients with four patients lost during the follow-up period. Post-operative complications were observed in 12 patients included hearing loss, cerebrospinal fluid leakage, worsening facial palsy, difficulty swallowing, dilpopia, and ataxia. Conclusions: Vein can play an important role and can be the offending vessel in MVD for HFS. Women with platysmal involvement and tonus seem to have higher chance of vein as an offending vessel. These patients that have residual LSR at the end of the procedure should undergo exploration for a vein to prevent persistent HFS. Intraoperative monitoring with LSR is an effective tool to evaluate adequate decompression to vein. Although the long-term outcome is excellent for venous compression, the complication rate is much higher. To decrease the complication rate, gentle retraction of the cerebellum and 'low-power' coagulation of the vein might be helpful.