Sleep in Mowat-Wilson syndrome (MWS): Clinical and polysomnografic study

Objective: In a recent study we described the electroclinical phenotype of epilepsy in MWS. The aim of the current study was to define sleep patterns in children with MWS and to evaluate age-related architectural and EEG evolution of sleep in this syndrome. Methods: Prospective study. Fourteen patients with molecularly confirmed MWS were included (age range 2–25 y, median 10 y). We administred to all parents the “Sleep Disturbances Scale for Children (SDSC)” questionnaire and all patients performed a full- night video-EEG-polysomnography. Results: SDSC questionnaires disclosed a high level of sleep disturbances: in 8/14 patients (57%) we found scores in pathological range in 2 subscales (“sleep–wake transition” and “initiating and maintaining sleep disorders”). Polysomnographic studies documented a reduction in sleep efficiency in 7/14 patients (50%), a decreased percentage and duration of REM sleep and an increased awakening index compared with normative values. In all patients we observed an EEG pattern characterized by slowing of background activity and poverty of physiological sleep features. Moreover in patients with age >4 y, anterior predominant spike and waves (SW) were observed. These abnormalities were markedly activated by sleep, in particular in the first cycle of NREM sleep, configuring a near-to-continuous SW activity. Moreover we recorded a subclinical frontal seizure in 1 patient. Conclusion: Our data (both clinical and polysomnographic) documented the presence of important and clinically relevant sleep disturbances in MWS patients. Moreover, we verified also during full-night sleep the presence of an age-dependent EEG pattern, as already described in our former study. We suggest that this pattern could be ascribable to a genetic etiology rather than a structural cause.