[Is the current level of investigation for vestibular schwannoma reasonable?]

The main aim of this study was to evaluate if the level of investigation with MRT or BRA (Brainstem Response Audiometry) is adequate in relation to the number of vestibular schwannomas (VS) found in a county like  Dalarna (277 000 inhabitants) in Sweden. The reason to investigate was asymmetrical sensorineural hearing loss (ASHL) defined as a one-sided hearing loss exceeding 10 dB compared to the contralateral side. Between 2007-2014 a total of 55 patients (incidence 2.5/100 000) were diagnosed with a VS in the county. The local ENT department found two thirds of these patients. In the year of 2010, MRT was advocated by SBU (Swedish Agency for Health Technology Assessment and Assessment of Social Services) as the primary step of investigation. During 2011-2014, 981 patients underwent MRT and 482 patients BRA, because of ASHL. Seventeen VS were found, meaning that 58 MRT and 29 BRA were conducted to find one VS. According to earlier studies, only one third of VS show growth tendency. Taking this into consideration, 174 (58 × 3) investigations with MRT will only diagnose approximately 1 patient with a growing VS. We therefore question today's level of investigation and ask for new uniform recommendations on how to investigate for VS in cases of ASHL.