[Effect of hyperlipidemia and hypothyroidism on auditory evoked brain stem responses].

Temporary changes in audiometry have been reported in hypercholesterolaemia and in hypo- and hyperthyroidism. The purpose of the present prospective and controlled study was to record changes in conduction time of auditory brain-stem response (ABR) in patients with hyperlipidaemia and hypothyroidism before and after therapy over a period of 6 months. The acoustic evoked brain-stem response Jewett waves I-V were delayed in patients with hypercholesterolaemia, hypertrigliceridaemia and hypothyroidism in comparison with an age-matched control group. The changes in pure-tone threshold and brain-stem responses correlated with the degree of hyperlipidaemia or hypothyroidism. After treatment the brain-stem responses of hypothyroid patients tended to return to normal, and in a few cases normal pure-tone thresholds were achieved. Of the patients with hypercholesterolaemia and hypertrigliceridaemia, 28% had improvements in pure-tone thresholds, whereas no significant changes were found in the ABR following therapy.