People with migraines are more likely to have lowered otoacoustic emissions (OAE) and auditory brainstem responses (ABR), which are early indicators of impending auditory dysfunction that can lead to hearing loss, the study shows.
In addition, nearly two-thirds of the migraine patients had one or more abnormality in auditory electrophysiological testing, despite almost all of them being classified as having a normal hearing level. Auditory dysfunction symptoms such as phonophobia (fear of loud noises) and tinnitus were present in 20.7% and 13.8% of individuals, respectively.
Compared with a control group, migraine patients had significantly lower amplitudes of transient evoked OAE (TEOAE) at frequencies of 1 kHz, 3 kHz, and 4 kHz.
They also had significantly lowered amplitudes of distortion product OAE (DPOAE) at frequencies of 1 kHz, 2 kHz, 3 kHz, and 5 kHz.
TEOAE and DPOAE are generated when the ear's outer hair cells, which are responsible for cochlear sound amplification, move in response to acoustic stimuli - a process known of as electromobility.
"Otoacoustic emissions permit sensitive assessment of cochlear function and objectively monitor dynamic changes in cochlear responsiveness before functional and significant hearing loss occurs from any cause," explains Sherifa Ahmad Hamed (Assiut University Hospital, Egypt) and colleagues.
Patients with migraines also reported prolonged latency of wave III and I-V interpeak latency of ABR at high rate frequencies, indicating central auditory dysfunction.
The report was published in the American Journal of Otolaryngology.