The patient's audiogram shows a moderately severe to severe sensorineural hearing loss on the right. Even though the hearing loss is significant on that side, there is asymmetry, with even worse hearing loss on the left. Asymmetric hearing loss has been defined as a difference of 15 dB between the right and left ears at three contiguous frequencies.No matter the degree of loss, asymmetric hearing loss requires further evaluation. Generally, this workup includes auditory brainstem response (ABR) testing or MRI. While ABR testing has the advantage of a much lower cost compared with MRI, its sensitivity also is a lot lower for small tumors.The patient's MRI, which is shown in figure 1, reveals a large cerebellopontine angle tumor on the side of the asymmetric loss. The most common tumor in the cerebellopontine angle is a vestibular schwannoma.
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