Aim: Mowat–Wilson Syndrome (MWS) is a genetic rare disease. Epilepsy is present in 70–75% of Patients and an age-dependent
electroclinical pattern has been described. Up to date, there are studies with overnight sleep EEGs, probably because of the severe
intellectual disability (ID) and hyperactivity of these Patients.
Our purpose was to verify the hypothesis that MWS Patients might have electrical status epilepticus in slow wave sleep (ESES
pattern).
Methods: A retrospective analysis of anamnestic and electrographic data was performed on 7 consecutive MWS Patients followed
between 2007 and 2016. Only Patients with at least one overnight sleep EEG were included in the study.
Results: Five out of 7 Patients had overnight sleep EEG studies and were included in this study. All of them had an anterior
ESES pattern with spike-and-wave index > 85%. The architecture of sleep was abnormal. An ESES related regression of cognitive
and motor functions with impact on daily activities (ESES-related syndrome) was demonstrated in 3 out of 5 (60%) Patients. In two
Patients marked improvement of cognitive and motor performances was observed when the epileptiform activity during sleep was
successfully controlled or it was spontaneously reduced.
Conclusions: The clinical significance of the ESES pattern is hard to assess in MWS Patients due to severe ID, but changing in
behaviour or in motor and cognitive functions should mandate sleep EEG investigation and, if ESES is present, an appropriate
treatment should be tried. Furthermore, overnight sleep EEG recordings, if regularly performed in the follow up, might help to
understand if ESES pattern hampers the cognitive and communicative profile in MWS.
