Internal Auditory Canal Glioneural Hamartoma: A Rare Mass Masquerading as a Vestibular Schwannoma

Glioneural hamartomas are exceedingly rare lesions. When localized to the internal auditory canal (IAC), they can cause symptoms referrable to seventh and eighth cranial nerve compression. Here, the authors present a rare case of an IAC glioneural hamartoma. A 57-year-old male presented for evaluation of presumed intracanalicular vestibular schwannomas found on work-up of dizziness and progressive right-sided hearing loss. Surgical intervention pursued progressive symptoms and new onset headaches. The patient underwent uncomplicated retrosigmoid craniectomy for gross total resection. Histopathological evaluation revealed a glioneural hamartoma. A MEDLINE database search used the terms' cerebellopontine angle' OR 'internal auditory canal' AND 'hamartoma' OR 'heterotopia'. Clinicopathological characteristics and outcomes of the present case were compared to those in the literature. The literature review yielded nine articles describing 11 cases (eight females, three males; median age 40 years, range 11-71) of intracanalicular glioneural hamartomas. Patients most commonly presented with hearing loss and were presumed to have a diagnosis of vestibular schwannoma before histologic diagnosis. Glioneural hamartomas are rare lesions that may be found in the IAC. Although benign, they may be safely resected for cranial nerve function preservation goals with a low risk of recurrence.