A Case-Case Analysis of Intralabyrinthine Schwannoma Versus Intracanalicular Vestibular Schwannoma.

Abstract

Determine the differences in presentation of intracanalicular and intralabyrinthine schwannomas. Retrospective chart review at a single center. Tertiary academic referral center. Eighteen subjects with an intralabyrinthine schwannoma (ILS) and 216 patients with an intracanalicular vestibular schwannoma (VS). Variables collected included age at diagnosis, gender, presenting signs and symptoms, imaging findings, treatment modality, pure-tone average (PTA), and word recognition scores (WRS) at presentation and at follow-up visits. Incidence of subjective hearing loss was 100% in the ILS group and 80.6% in the intracanalicular VS group. The degree of hearing loss was significantly worse in the ILS group (average PTA of 83.9 dB; average WRS of 46.9%) compared with the VS group (average PTA of 38.7 dB; average WRS of 71.8%) (PTA p = 0.000006; WRS p = 0.007). Other subjective signs and symptoms, including vestibular symptoms, did not differ significantly between the two groups. Approximately one-third of both groups underwent microsurgical resection. 22.2% of ILSs were missed on initial imaging by radiologists. Intralabyrinthine schwannomas differ from intracanalicular schwannomas in the severity of hearing loss at presentation. Otherwise, these two tumors present in a very similar fashion-age at presentation, presenting signs and symptoms-and are treated comparably. Otolaryngologists should maintain a high degree of suspicion for ILS in patients presenting with an asymmetric hearing loss, vertigo, and tinnitus.