Intralabyrinthine Schwannoma of the Intravestibular Subtype: A Difficult Diagnosis

Intralabyrinthine schwannoma is a rare, slow-growing, benign tumor that affects the most terminal portions of the vestibular and cochlear nerves. It can be located in the vestibule, cochlea, or semicircular canals. In 2004, Kennedy et al proposed a classification system which recognized 7 subtypes of intralabyrinthine schwannoma; in 2013, Abel et al1 modified the Kennedy classification,2 which included intracochlear, intravestibular (IV), intravestibulocochlear, transmodiolar, transmacular, transotic, and tympanolabyrinthine, to also include translabyrinthine, tumors extending into the CPA, and tumors not otherwise specified. They also proposed to rename intralabyrinthine schwannoma as primary inner ear schwannoma to permit clear subsite categorization. Patients usually have nonspecific symptoms, including hearing loss, tinnitus, and only single episode of vertigo. Among the resulting symptoms, the most frequent is hearing loss, which affects 95% of the patients. Most times, this loss is slow and progressive, but it may be sudden or fluctuating. Less common symptoms include tinnitus (51%), imbalance (35%), vertigo (22%), and ear fullness (2%), which may be present alone or in combination.3-7 We report a rare case of a patient with hearing loss and single episode of vertigo secondary to the intralabyrinthine schwannoma of the IV subtype.