REM sleep atonia in patients with pediatric acute-onset neuropsychiatric syndrome (PANS): implications for pathophysiology.

Study objectives: Sleep disorders and/or disordered sleep represent common clinical presentations of pediatric acute-onset neuropsychiatric syndrome (PANS), occurring in up to 80% of affected children, with REM sleep motor disinhibition being a prevalent feature. To date, limited polysomnographic (PSG) studies have been conducted. Therefore, the objective of this study was to evaluate the PSG characteristics of a cohort of children with PANS, focusing particularly on REM sleep without atonia (RSWA) as assessed by the REM atonia index (RAI), and to compare these characteristics with those of a control group.

Methods: Sixty-nine patients diagnosed with PANS were consecutively recruited who underwent comprehensive PSG examinations following standard criteria. Chin muscle tone during REM sleep was evaluated using RAI. Forty-four healthy subjects, matched for age and sex, were used as controls.

Results: RAI was significantly lower in patients compared to controls. In controls, RAI showed a significant progressive increase with age from preschool to adolescence. Conversely, this age-related trend was absent in patients, with no significant correlation between RAI and age, with a random distribution of values. Only one control subject (1/43) but 25 patients (25/57) exhibited a RAI below the lower limit of the predicted range obtained from controls.

Conclusions: Our findings underscore the significance of REM sleep abnormalities in children with PANS. The substantial reduction in RAI and the lack of correlation between RAI and age observed in patients suggest a potential pathological mechanism leading to dysfunction in brainstem structures regulating REM sleep atonia in this population.