[Disturbance of active sleep components in neonates with congenital hypothyroidism].

In order to investigate the effect of hypothyroidism during the early development on the functional brainstem maturation, polysomnograms were recorded on 7 patients with congenital hypothyroidism detected by neonatal screening before treatment. The following two sleep indices for phasic muscle activity during rapid eye movement (REM) sleep were evaluated: dissociation index (DI) and % body movements in REMs burst (% BM). The DI is defined as the ratio of the number of twitch movements (TMs) during REM sleep to the sum of TMs and localized movements (LMs) during REM sleep. The % BM is the percentage of TMs and LMs which occur during bursts of REMs in relation to the sum of TMs and LMs during REM sleep. The DI and % BM can reflect maturation of the tonic and phasic inhibitory system functioning during REM sleep, respectively. In congenital hypothyroidism, DI was lower than that in controls, while % BM was identical. The tonic inhibitory system was specifically involved, whereas the phasic one was preserved. It is suggested that thyroid hormone could play an important role on the functional brainstem maturation. We propose to investigate their neuropsychological development over the long term to elucidate the influence of hypothyroidism.