Characteristics of pure tone audiogram in patients with untreated sporadic vestibular schwannoma: Analysis of audiometric shape and interaural differences stratified by age and mode of onset.

ABSTRACT

OBJECTIVE: Asymmetric sensorineural hearing loss (ASHL) is the most common symptom of sporadic vestibular schwannoma (VS). However, there is still no universally accepted MRI protocol for diagnosing VS. This study identified the characteristics of pure tone audiogram (PTA) in patients with VS. METHODS: We conducted a retrospective chart review of patients diagnosed with sporadic unilateral VS. In the analysis, we focused on the shape and interaural differences of PTA, stratified by the mode of onset and patient age. RESULTS: In total, 390 patients met the inclusion criteria. The U-shaped audiogram showed the highest proportion in patients with the onset of sudden sensorineural hearing loss (SSNHL). In patients with SSNHL, U-shaped audiograms were younger than other audiograms, and 86.7 % of patients under 40 had U-shaped audiograms. Patients with VS were more likely to have interaural differences at higher frequencies than at lower frequencies. Patients with SSNHL had a significantly higher percentage of interaural differences at 500-4000 Hz than those with onset other than SSNHL (non-SSNHL patients). In addition, non-SSNHL patients had a significant trend toward a higher percentage of interaural differences at all frequencies with increasing age. CONCLUSION: MRI screening can be considered in patients with SSNHL with U-shaped audiograms under 40 years of age. In ASHL, not SSNHL, MRI screening can be considered for older patients with interaural differences at wider continuous frequencies. Patients with interaural differences at high frequencies had a higher priority than those with interaural differences at low frequencies as indications for MRI screening for VS.