Periodic sighs

A 2 year-old girl, affected by achondroplasia, underwent an overnight, laboratory-based video-polysomnographic study aimed to study the respiratory pattern in sleep. The parents reported repeated episodes of ‘respiratory pauses’ during sleep. No parasomnia, rhythmic movements during sleep, snoring or noisy breathing was reported; otorhynolaringoiatric evaluation was unremarkable, body mass index was 21.5, no diurnal symptoms of sleepiness or other behavioral modifications were present. Neurological examination was normal, and no evidence of cardiac or respiratory pathologies were present. Sleep EEG was normal, and NREM and REM sleep stages were recorded. During all NREM sleep stages, PSG recording showed recurrent sighs, characterized by increase of the airflow signal. Sighs repeated periodically, were associated in most cases with an EEG arousal, and were followed by a short respiratory pause (a brief apnea of central type, not associated with EEG arousal and not followed by modifications in peripheral haemoglobin desaturations). Video recording confirmed that PSG sighs consisted in a deep breath, followed by a short lasting (2-4 seconds) respiratory pause.