Otoacoustic emission in patients with neurological disorders who have auditory brainstem response abnormality

Otoacoustic emissions (OAEs) were evaluated in 51 ears of 30 patients with a severe auditory brainstem response (ABR) waveform abnormality. Thirteen ears showed no ABR to click sound of higher intensity than 100 dBSPL (group 1). Fourteen ears exhibited only wave V or a decreased amplitude pattern of ABR (group 2). Twenty-four ears showed a predominant wave I or no wave III pattern (group 3). Almost all the ears with absent ABR showed no OAE, which strongly suggested hearing loss of cochlear origin, although one patient with alternating hemiplegia of childhood exhibited definite OAEs and auditory reactions without ABR. One patient with mitochondrial myopathy, encephalopathy, lactic acidosis, and strokelike episodes (MELAS) and her mother in group 2 had OAE abnormalities, which also suggested mild to severe hearing impairment. When OAEs are present, an accompanying ABR abnormality may be produced by brainstem dysfunction of the underlying disorder such as Pelizaeus-Merzbacher disease. There was a significant relationship (chi-square test P<0.001) between the positivity of the distortion product OAE response and the clinical auditory reactions in 24 patients, although their ABR abnormalities did not reflect hearing impairment directly. Careful examination of both audiometry and OAEs might be necessary for further assessment of the hearing function in pediatric patients with neurological disorders and specific auditory nerve disease.