AUDITORY BRAIN-STEM RESPONSES (ABRS) IN SLEEP RESPIRATORY DISORDERS

Neurophysiological repercussions of sleep respiratory disorders (SRDs) are still unclear. It has been shown that SRDs induce disturbance on auditory event-related potentials with a delayed latency of the cognit ive P300 potentials. Since the Auditory Brainstem Responses (ABRs) exp lore the auditory brainstem structures and an independent on cognition , we evaluated the neurological impact of SDRs on central nervous syst em by AB Rs in these patients. Four groups of patients were studied: s norers (S, 17 subjects), sleep apnoea syndrome (SAS, 48 subjects), apn oeic patients with respiratory insufficiency (SAI, 17 patients) and pa tients with respiratory insufficiency alone (RI, 12 subjects). A stand ard polysomnographic study was done in each patient with further quant itative analysis of sleep, respiratory events, and oxygen arterial sat uration. ABRs were recorded before the study night and interpeak laten cies (IPLs) between waves I, III and V were measured. Results were exp ressed as the mean of each group for all the different parameters. ABR IPL latencies (IPL(I-III), IPL(III-V), IPL(I-V)) of the four groups w ere within the normal range. However, comparing groups between themsel ves, there were significant differences (ANOVA) between groups. Longer IPL(III-V) and IPL(I-V) (which explored the central conduction time) were observed in group SAI compared to group SAS. No evidence on the o rigin of this elongation was found; the level of hypoxia, in particula r, was not related to IPL values. These results show that SAS alone do not affect lower brainstem auditory function, in contrast to the asso ciation of SAS and RI.