Prevalence and characteristics of sleep-disordered breathing in familial dysautonomia.

Objective: Familial dysautonomia (FD) is an autosomal recessive disorder characterized by impaired development of sensory and afferent autonomic nerves. Untreated sleep-disordered breathing (SDB) has been reported to increase the risk of sudden unexpected death in FD. We aimed to describe the prevalence and characteristics of SDB in FD.

Patients/methods: Seventy-five patients with FD (20 adults and 55 children) underwent in-lab polysomnography, including peripheral capillary oxygen saturation (SpO) and end-tidal capnography (EtCO) measurements. A t-test and Spearman's correlation analysis were performed to evaluate the impact of age on sleep, occurrence of apneas, SpO and EtCO levels; and to determine the relationship between apneas and SpO/EtCO measurements during different sleep stages.

Results: Overall, 85% of adults and 91% of pediatric patients had some degree of SDB. Obstructive sleep apneas were more severe in adults (8.5 events/h in adults vs. 3.5 events/h in children, p = 0.04), whereas central apneas were more severe (10.8 vs. 2.8 events/h, p = 0.04) and frequent (61.8% vs. 45%, p = 0.017) in children. Overall, a higher apnea-hypopnea index was associated with increased severity of hypoxia and hypoventilation, although in a significant fraction of patients (67% and 46%), hypoxemia and hypoventilation occurred independent of apneas.

Conclusion: Most adult and pediatric patients with FD suffer from some degree of SDB. There was a differential effect of age in the pattern of SDB observed. In some FD patients, hypoventilation and hypoxia occurred independently of apneas. Therefore, we recommend including EtCO monitoring during polysomnography in all patients with FD to detect SDB.