Audiological Findings and Non-Audiological Correlates in Individuals with Acoustic Neuroma: A Systematic Review

Abstract

Tumors affecting the eighth cranial are often referred to as eighth nerve tumors, acoustic neuromas or vestibular schwannoma, acoustic neurilemomas, acoustic neurinomas, and acoustic tumors. Many individuals with vestibular schwannoma experience hearing loss along with tinnitus and dizziness. The accurate diagnosis of acoustic neuromas requires audiological evaluation, radiological evaluations, and other brain imaging findings. This review study aims to compile the articles comprising audiological and non-audiological evaluations of computed tomography (CT) and Magnetic resonance imaging (MRI) and their correlations in individuals with acoustic neuroma. The full-length articles published in the English language during the past ten years (2011 – 2021) were selected for this systematic review. These selected studies were analyzed using the CASP (Critical Appraisal Skills Programme) checklist for qualitative research to avoid the risk of bias. Of 38 full-length articles, 13 studies were included in the systematic review. The results of these articles reported that most patients with acoustic neuroma have significant unilateral hearing loss, mostly descending or sloping type. Along with the hearing loss, these individuals showed marked abnormality in auditory brainstem response (ABR) peaks and a decrement in the speech discrimination scores. About 4 to 6% of the patients with acoustic neuroma did not show any symptoms of hearing loss. The audiological test results did not significantly correlate with the tumor size or the site. However, small tumors or tumors at the early stage are difficult to find and diagnose through audiological tests alone. Non-audiological evaluations such as CT and MRI have increased the diagnosis of acoustic neuroma at the early stage. The incidence of vestibular schwannoma has increased globally during the past thirty years. This systematic review insists on the utility of non- audiological evaluation in diagnosing acoustic neuroma, even though the patient shows no audiological symptoms such as hearing loss and tinnitus. Also, it recommends the audiologist consider the radiological findings while determining the diagnosis in patients indicating unilateral hearing loss, sudden SNHL, tinnitus, reduced speech understanding, and dizziness.