Results and Sensitivity of a Comprehensive Audiological and Vestibular Work-Up in 100 Patients Presenting with a Vestibular Schwannoma

Abstract

Purpose: To determine the results and sensitivity of a comprehensive audiological and vestibular work-up in 100 patients presenting with a vestibular schwannoma (VS). Material and Methods: One hundred consecutive cases of VS diagnosed from January 2004 to May 2005 were prospectively studied. Tumor size was classified according to the Koos classification and hearing was assessed according to the five-step Kanzaki classification. A comprehensive work-up was conducted in all patients, including complete tone and speech audiometry, brainstem evoked audiologic potentials (BEAP), vestibular evoked myogenic potentials (VEMP), and bithermal caloric testing using videonystagmography on both sides. BEAP responses were considered as normal or endocochlear when interwave intervals were normal, absent because of a poor hearing, or retrocochlear when interval between, wave 1 and 5 > 4.3 ms and/or when it differed > 0.25 ms between sides, or when no response was recorded when hearing was preserved. VEMP were considered as normal, absent, or diminished (amplitude 30%) or arreflexia (diminished > 80%). Results: Fifty-six females and 44 males were examined (mean age, 57.8 yrs). Left and right sides were equally affected. Vertigo, tinnitus, and hearing loss were the main presenting symptoms in 21%, 32%, and 68% of cases, respectively. Eighty-two percent were operated, 17% simply monitored, and 1% irradiated. The tumor was Stage 1, 2, 3, and 4 in 14%, 28%, 21%, and 37%, respectively. Hearing was class A in 9%, class B in 34%, class C in 14% and class E-D in 43% of the cases. Globally, BEAP showed a retrocochlear pattern in 64% of the cases and no response in 30%. Abnormal VEMP responses were observed in 94% of the cases. Caloric testing was abnormal in 61% and normal in 11%. Responses could not be analyzed in 28% of patients. Only one patient showed normal responses to the whole work-up (99% sensitivity); she suffered a very small intrameatal tumor and complained of contralateral audiological symptoms. Conclusion: An integrated neurotologic work-up is a powerful tool to diagnose all sizes of VS and is useful in predicting postoperative outcome. However, false-negative results remain possible in small intrameatal tumors (1%).