Electrocochleography and Auditory Brainstem Responses in Persons with Non-Optimal Blood Pressure

Abstract

Background Numerous cardiometabolic factors may underlie risk of hearing loss. Modifiable risk factors such as non-optimal blood pressure (BP) are of interest. Purpose To investigate early auditory evoked potentials (AEPs) in persons with nonoptimal BP. Research Design A cross-sectional nonexperimental study was performed. Study Sample Fifty-two adults (18–55 years) served as subjects. Individuals were classified as having optimal (systolic [S] BP < 120 and diastolic [D] BP < 80 mm Hg, n = 25) or non-optimal BP (SBP ≥=120 or DBP ≥=80 mm Hg or antihypertensive use, n = 27). Thirteen subjects had hypertension (HTN) (SBP ≥130 or DBP ≥80 mm Hg or use of antihypertensives). Data Collection and Analysis Behavioral thresholds from 0.25 to 16 kHz were collected. Threshold auditory brain stem responses (ABRs) were recorded using rarefaction clicks (17.7/second) from 80 dB nHL to wave V threshold. Electrocochleograms were obtained with 90 dB nHL 7.1/second alternating clicks and assessed for summating and compound action potentials (APs). Outcomes were compared via independent samples t tests. Linear mixed effects models for behavioral thresholds and ABR wave latencies were constructed to account for potential confounders. Results Wave I and III latencies were comparable between optimal and non-optimal BP groups. Wave I was prolonged in hypertensive versus optimal BP subjects at stimulus level 70 dB nHL (p = 0.016). ABR wave V latencies were prolonged in non-optimal BP at stimulus level 80 dB nHL (p = 0.048) and in HTN at levels of 80, 50, and 30 dB nHL (all p < 0.050). DBP was significantly correlated with wave V latency (r = 0.295; p = 0.039). No differences in ABR amplitudes were observed between optimal and non-optimal BP subjects. Electrocochleographic study showed statistically comparable action and summating potential amplitudes between optimal and non-optimal BP subjects. AP latencies were also similar between the groups. Analysis using a set baseline amplitude of 0 μV showed that hypertensive subjects had higher summating (p = 0.038) and AP (p = 0.047) amplitudes versus optimal BP subjects; AP latencies were comparable. Conclusion Elevated BP and more specifically, HTN was associated with subtle AEP abnormalities. This study provides preliminary evidence that nonoptimal BP, and more specifically HTN, may be related to auditory neural dysfunction; larger confirmatory studies are warranted.