Disordered breathing during sleep in patients with mucopolysaccharidoses

Obstructive sleep apnoea (OSA) has been reported as a feature of children with mucopolysaccharidoses (MPS). However, the incidence and severity of OSA with respect to disease type is poorly defined. The aim of the present study was to measure objectively the degree of OSA in a group of children with a range of MPS syndromes.

In a cross-sectional study, cardiopulmonary sleep studies were performed during unsedated sleep in 26 children with MPS over a period of 2 years. Scores of OSA severity based upon clinical history and upon objective sleep study data were made in each case and compared.

OSA was present in 24/26 patients, and ranged in severity from mild to severe. OSA was most marked in MPS type IH (Hurler syndrome) followed by types IHS (Hurler--Scheie syndrome) and II (Hunter syndrome). Frequent arousals and poor sleep quality, not suspected clinically, were noted in several patients. There was agreement between the clinical and objective scoring systems in only 17/26 patients (65%) with clinical history scores tending to underestimate the most severe cases (5/26 cases) and overestimate the severity in the mild cases (4/26 cases).

Obstructive respiratory problems are frequent in MPS patients and there are differences in severity of OSA between the different MPS types. Assessments of the severity of OSA based upon clinical history alone are inadequate. Our results suggest that objective sleep studies are necessary to evaluate these cases, to monitor clinical outcome and to assess the effects of therapeutic intervention. Prospective studies in larger numbers of patients are needed to validate these observations.