We describe a 2-year-old baby affected by
Smith-Magenis syndrome (SMS), due to 17p11.2 deletion, who presented repeated episodes of
hemoglobin desaturation during REM sleep. The boy, aged 14 months, presented a phenotype characterized by psychomotor delay, right posterior
plagiocephaly,
telecanthus,
strabismus, upslanting palpebral fissures, broad hypoplastic nasal bridge, short philtrum, deep ring shaped skin creases around the limbs, proximal
syndactyly, bilateral hypoacusia. Polysomnographic (PSG) recording showed episodes of REM-related
hypoventilation (
hemoglobin desaturations without
apneas or hypopneas).
Sleep disorders are present in almost all the cases of SMS, but very few reports describe the sleep-related respiratory patterns. The finding of REM
hypoventilation in SMS does not allow an unequivocal interpretation. It could reflect a subclinical restrictive respiratory impairment or, alternatively, an impairment of central respiratory control during REM sleep. In SMS children, respiratory abnormalities during sleep, and in particular during REM sleep, may cause sleep disruption, reduction of time spent in REM sleep, and
daytime sleepiness. We therefore suggest that some sleep abnormalities described in SMS could be consequent to
Sleep Disordered Breathing, and in particular to REM
hypoventilation. Sleep studies in SMS should include the recording of respiratory parameters.