Hearing improvement following gamma knife radiosurgery for an intra-canalicular vestibular schwannoma

Abstract

Pure tone audiometry revealed a moderate sensorineural hearing loss (50 dB) in the left ear [Figure 1]a. Contrast magnetic resonance imaging (MRI) of the brain revealed a small left intracanalicular VS [Figure 2]a. After appropriate counseling, primary GKRS was performed using a Leksell gamma knife unit B model. {Table 1} Various factors have been implicated in hearing preservation in GKRS for VS, which include grade 1 pre-operative Gardner-Robertson hearing, speech discrimination score >80%, age <60 years, intracanalicular tumor location, low intracanalicular dose, tumor volume <0.75 cc, ventral cochlear nucleus dose ranging from <9 Gy to <10 Gy, lesser tumor coverage, normal auditory brainstem response and early resection of intracanalicular VS when acutely symptomatic.