Power spectrum auditory brainstem response: novel approach to the evaluation of patients with unilateral auditory symptoms.

ABSTRACT

BACKGROUND: Unilateral hearing loss and audiovestibular symptoms are common in the population and can be associated with retrocochlear tumours such as acoustic neuroma (AN). In order to rule out AN, many patients with asymmetric hearing loss are referred for magnetic resonance imaging (MRI). Recent work with modifications of auditory brainstem response (ABR) protocols has improved the ability of ABR to detect small acoustic tumours. This study presents our initial results using the power spectrum ABR (PSABR) as another tool in detecting patients at higher risk for AN. METHODS: A prospective, observational cohort design was employed and a total of 53 subjects were recruited (19 subjects were normal controls and 34 subjects were patients with unilateral audiovestibular symptoms). All subjects underwent complete auditory testing, standard ABR, stacked ABR, and power spectrum ABR. The 34 patients also underwent gadolinium enhanced MRI. RESULTS: Using logistic regression, our data showed that wave I-V latency was most highly predictive of tumour presence or absence. However, both stacked ABR and power spectrum ABR were predictive. Stacked ABR was also able to differentiate symptomatic patients with tumours from those without. CONCLUSIONS: This study was not designed to compare PSABR to other more established methods. Rather, our intent was to establish PSABR as a valid and practical addition to other ABR tools. More research is needed to optimize PSABR algorithms, and the method also needs to be tested and validated in larger populations of patients. Early results do indicate that PSABR could be a valid and reliable method of identifying subgroups of patients with unilateral auditory dysfunction who would best benefit from MRI.