Evaluating Transient Hemifacial Spasm that Reappears After Microvascular Decompression Specifically Focusing on the Real Culprit Location of Vascular Compression

Abstract

Even although microvascular decompression is the standard treatment for hemifacial spasm (HFS), the treatment is not always 100% successful. Some patients experience the reappearance of HFS after temporary relief after surgery. We analyzed our data to elucidate the reasons for and prognosis of HFS reappearance, specifically focusing on exact compressive location of the facial nerve. The patients were divided into 2 groups: group A, the patients whose symptoms of spasm disappeared immediately after surgery but recurred within a month, and group B, the patients whose symptoms of spasm completely disappeared and never recurred. We adopted the terms of subdivision in the facial nerve root exit zone: RExP, root exit point; AS, attached segment; RDP, root detachment point; TZ, transition zone; and CP, distal cisternal portion. Among 115 patients, 56 (48.7%) belonged to group A and 59 (51.3%) to group B. In 54 of the 56 patients in group A (96.4%), the reappearing HFS disappeared gradually over several weeks. The precise location of compression in group A was at the RExP in 46.4% of the patients, AS in 33.9%, RDP in 16.1%, and TZ in 3.6%, and the RExP compression was significantly more frequent compared with in group B. After microvascular decompression for HFS, almost half of the patients experienced transient HFS recurrence despite sufficient decompression of the facial nerve. However, in most cases, recurrent HFS gradually resolved over a period. Based on the compression location, the surgeon could anticipate recurrence of transient HFS.