By Sally Robertson, MedWire Reporter
People who suffer from migraines are at an increased risk for developing hearing loss, report researchers.
Such individuals 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, they say.
As reported in the American Journal of Otolaryngology, an assessment of 58 migraine sufferers showed that auditory dysfunction symptoms phonophobia (fear of loud noises) and tinnitus were present in 20.7% and 13.8% of individuals, respectively.
In addition, nearly two-thirds of the migraine patients had one or more abnormalities in auditory electrophysiologic testing, despite almost all of them being classified as having a normal hearing level.
Compared with 40 matched controls, 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 electromotility.
"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," explain Sherifa Ahmad Hamed (Assiut University Hospital, Egypt) and colleagues.
Patients with migraine also reported prolonged latency of wave III and I-V interpeak latency of ABR at high rate frequencies, indicating central auditory dysfunction.
However, basic audiologic examination revealed that few patients had evidence suggesting a conductive hearing problem - otoscopy and standard aural imittance procedures confirmed normal middle ear status in all but five ears.
The finding that migraine patients are at high risk for peripheral and/or central auditory dysfunction is important for specialists caring for these patients, say Hamed and team.
In addition, migraine should be considered in patients with unknown hearing loss, they conclude.
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