Last Updated: 2008-04-11 17:06:46 -0400 (Reuters Health)

NEW YORK (Reuters Health) – Otoacoustic emission testing, which allows monitoring of minute changes in cochlear status, shows dysfunction of cochlea and cochlear efferents in patients with migraine, Turkish researchers report in the April issue of Cephalalgia.

"We unraveled a mechanism that leads to problems with discrimination of tones and lateralization of sound, particularly in a noisy environment, in patients with migraine," lead investigator Dr. Hayrunnisa Bolay told Reuters Health.

"This novel finding," she added, "could be one of the mechanisms underlying increased sensitivity and discomfort to auditory stimuli in migraineurs."

Dr. Bolay and colleagues at Gazi University Hospitals, Ankara, conducted otoacoustic emission and other testing in both ears of 53 patients with migraine and 41 controls. Both groups showed normal distortion product otoacoustic emission functioning of the inner ear at frequencies between 1 and 4kHz.

Among other findings were that in controls, the mean amplitudes of transiently evoked otoacoustic emissions showed a significant decrease in response to contralateral sound stimulus. However, this was not the case in the migraineurs.

"The data," continued Dr. Bolay, "provide evidence for subclinical nervous system abnormality that is widely distributed from the cerebral cortex to the neuromuscular junction, and would probably be a characteristic underlying susceptibility to migraine attacks."

"I think," she concluded, that "dysfunctional central mechanisms modulating the cochlear activity demonstrate another aspect of the migrainous brain in handling sensory signals."

Cephalalgia 2008;28:309-317.

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