Date of Graduation

Spring 2023

Degree

Doctor of Audiology

Department

Communication Sciences and Disorders

Committee Chair

Wafaa Kaf

Abstract

Migraine is a disabling neurological disease that is characterized by prominent auditory symptoms, including hyperacusis, which is defined as extreme sensitivity to sounds. The goal of this study was to investigate changes in hearing sensitivity and neural changes in the brainstem by measuring neural activity of the auditory brainstem in an established preclinical model of chronic migraine. To induce a chronic migraine state within the trigeminal system, male and female Sprague Dawley rats were subjected to three known human risk factors including neck muscle tension and REM sleep deprivation that promote latent sensitization, and exposure to a pungent odor, which acts as a trigger to stimulate trigeminal activation and pain signaling. Tone burst auditory brainstem responses (ABRs) were measured using the Duet device (Intelligent Hearing Systems, Miami, FL) to determine the effects of migraine pathology on brainstem auditory pathways in eight male and six female rats at baseline (naïve) condition and post migraine condition. Tone burst ABR was recorded in each ear to 4 kHz, 12 kHz, 22 kHz, and 32 kHz stimuli. To assess neural changes in the brainstem, suprathreshold ABRs were recorded at 80 dB sound pressure level and waveform morphology, latency, and amplitude responses were analyzed. To determine the threshold, tone burst ABR was recorded at 50 dB and 20 dB and then at 30 dB or 10 dB depending on the response at 20 dB. The threshold value was defined as the lowest intensity to elicit a reliable wave II, which is the largest wave in rats. At baseline (naïve condition), the 80 dB ABR morphology exhibited the presence of distinct waves I, II, and III at lower frequencies (4 kHz and 12 kHz) and waves I, II, III, IV, and V at higher frequencies (22 kHz and 32 kHz), with wave II being the largest wave. As the frequencies increased from 4 kHz to 32 kHz, latencies decreased, and amplitudes increased with a larger amplitude observed in the right ear at 4 kHz and 12 kHz (wave II mean = 1.98 µV) compared to the left ear (wave II mean = 1.65 µV). After induction of migraine pathology, ABR thresholds were elevated to mild-moderate degree, latencies decreased at 4 kHz, 12 kHz, 22 kHz, and 32 kHz and amplitudes increased, mainly wave II, at 4 kHz and 32 kHz. Results from this novel study provide, to our knowledge, the first evidence of neural changes in auditory brainstem response and changes in high frequency hearing sensitivity in a preclinical chronic migraine model.

Keywords

migraine, hearing sensitivity, hyperacusis, rat, auditory brainstem response

Subject Categories

Animal Sciences | Communication Sciences and Disorders | Laboratory and Basic Science Research | Neurosciences

Copyright

© Megan Huelsing

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