Functional changes in the brainstem auditory pathways following open-heart surgery.

Measurements of the auditory brainstem responses (ABR) were used to assess the functional integrity of the brainstem auditory pathways following open-heart surgery. Recording of ABR was performed in 31 patients before and after open-heart surgery. The values of ABR measurements were compared to those of a control group of normal-hearing subjects. Postoperative aberrations in ABR were observed in 12 patients. Brainstem transmission time measured as wave I to wave V interpeak latency (I-V IPL) was prolonged in 6 patients and shortened in 8 patients. Concomitant impairment in hearing function was not present, and therefore, these changes most probably reflected a functional alteration in the neurological status of the brainstem. Possible explanations of the postoperative changes in I-V IPL are discussed, however, further studies are needed to clarify the pathogenesis of these changes. Measurement of ABR may prove to be an important adjunct in the overall assessment of the neurological status following open-heart surgery.