Microvascular decompression for hemifacial spasm associated with the vertebral artery.

In patients with vascular compression syndromes, the preoperative recognition of the cranial nerves and compressed vessels will contribute to improved surgical results. The aim of this study was to clarify the pathophysiology of hemifacial spasm (HFS) associated with the vertebral artery (VA) and to assess the value of preoperative imaging. Fifty-three consecutive patients with HFS underwent microvascular decompression (MVD). Of these, 18 cases of HFS were associated with the VA; this case series was compared with the remaining non-VA-associated HFS. For preoperative assessment, magnetic resonance imaging (MRI) was performed. Since January 2006, fusion imaging has been performed by combining MRI and computed tomography angiography. Of the 18 cases of VA-associated HFS, 17 (94.4 %) were on the left side; this was significantly higher than in the non-VA-associated HFS cases (p < 0.0001). The VA was attached to the root exit zone (REZ) directly in three cases. In the other 15 cases, the VA was compressing the REZ indirectly as a result of other intervening vessels. In all cases, preoperative imaging fully simulated the status of the REZ. The symptom disappeared in 17 cases (94.4 %) after MVD, and there was no significant difference in the surgical results between the VA-associated group and the non-VA-associated group (p = 0.9925). HFS associated with VA is not a rare condition. Preoperative recognition is thus important to the improvement of surgical results. Fusion imaging is useful to determine the status of the REZ, especially in indirect VA-associated HFS.