Hearing loss commonly occurs after radiation therapy for an acoustic neuroma, and it is highly unusual for hearing to return after a prolonged period of time. We report the case of a 12-year-old boy with neurofibromatosis 2 who underwent fractionated stereotactic radiotherapy for the treatment of a left-sided vestibular schwannoma. Following treatment, he demonstrated an elevation of pure-tone audiometric thresholds and a sudden decrease in speech discrimination score (SDS) to 0%. However, 20 months postoperatively, his SDS suddenly and spontaneously rose to 92%, although there was no improvement in his speech reception threshold. We discuss the possible reasons for the unusual outcome in this patient.