A Case Report of Hemifacial Spasm Caused by Vestibular Schwannoma and Literature Review

Background: Most cases of hemifacial spasm result from mechanical compression at the root exit zone of the facial nerve by vascular loops, and only a few cases are caused by vestibular schwannoma. Case presentation: We report a case of symptomatic hemifacial spasm induced by a small vestibular schwannoma that was totally resected. A 64-year-old man was admitted to our department with a 14-month history of symptomatic right-sided hemifacial spasm. During the process of microvascular decompression, no definite vessel was found to compress the facial nerve. By further exploration of regions other than root exit zone, a small vestibular schwannoma compressing the internal auditory canal portion of facial nerve from the ventral side was discovered. Resection of the tumor was then conducted. The symptoms of hemifacial spasm disappeared immediately after surgery. Conclusions: We should be aware that magnetic resonance imaging is not always precise and perhaps misses some miniature lesions due to present image technique limitations. A small vestibular schwannoma might be the reason for HFS, although preoperative magnetic resonance tomography angiography showed possible vascular compression at the facial nerve root. More importantly, a full-length exploration of the facial nerve is in urgent need to find potential compression while performing microvascular decompression for HFS patients.