Don’t perform auditory brainstem responses (ABR) in patients with asymmetrical hearing loss. Asymmetrical hearing loss is defined as bone conduction threshold difference of: (a) 20 dB threshold difference at a single frequency, (b) 15 dB threshold difference at 2 frequencies, (c) 10 db threshold difference at 3 frequencies.

If there is no obvious cause of the asymmetry such as unilateral trauma or unilateral noise exposure like gun blasts, a MRI should be ordered. MRI scans are superior in sensitivity for detecting retrocochlear pathologies such as vestibular schwannoma when compared to ABR testing.

 

Sources:

Bozorg Grayeli A, et al. Diagnostic value of auditory brainstem responses in cerebellopontine angle tumours. Acta Otolaryngol. 2008 Oct;128(10):1096-100. PMID: 18607985.

Fortnum H, et al. The role of magnetic resonance imaging in the identification of suspected acoustic neuroma: a systematic review of clinical and cost effectiveness and natural history. Health Technol Assess. 2009 Mar;13(18):iii-iv, ix-xi, 1-154. PMID: 19358774.

Koors PD, et al. ABR in the diagnosis of vestibular schwannomas: a meta-analysis. Am J Otolaryngol. 2013 May-Jun;34(3):195-204. PMID: 23332407.