Mobilization of the Anterior/Posterior Inferior Cerebellar Artery on the Cerebellar Surface in Microvascular Decompression Surgery for Hemifacial Spasm: Potential Effect on Hearing Preservation.

Abstract

The infrafloccular approach in microvascular decompression (MVD) for hemifacial spasm (HFS) reduces the risk of postoperative hearing impairment. However, location of the anterior/posterior inferior cerebellar artery (AICA/PICA) on the cerebellar surface in the surgical route requires mobilization to maintain the approach direction for the protection of hearing function. To evaluate the effectiveness of mobilization of the AICA/PICA on the cerebellar surface in the surgical route. Retrospective review of 101 patients dividing their cases into 2 groups, the mobilized group and nonmobilized group. Surgical results, brainstem auditory evoked potentials (BAEPs), age, and duration of microsurgery were compared. In the mobilized group, whether the artery was responsible for the HFS or not, and whether the artery branched perforators to the cerebellar surface or choroid plexus or not, were analyzed. No permanent hearing impairment occurred in any patient. The AICA/PICA was mobilized in 26 patients. No significant difference was found in surgical results, BAEP findings, and duration of microsurgery between the 2 groups, but age was younger in the mobilized group (P<.01). The mobilized artery was responsible in 14 cases and branched perforators in 7 cases in the mobilized group. The perforators did not obstruct mobilization. Mobilization of the AICA/PICA from the cerebellar surface is a useful technique to maintain the infrafloccular approach in MVD for HFS. This technique reduces the risk of postoperative hearing impairment.