Sleep disordered breathing in myotonic dystrophy: A consecutive prospective cohort study

Abstract

Introduction: Excessive daytime hypersomnolence and tiredness contributes significantly to functional limitation in myotonic dystrophy. Sleep related disordered breathing (SRDB) contribution to EDS is poorly understood.(1) Methods: We recruited 21patients (10 males) with myotonic dystrophy. Baseline characteristics including Age, Body mass index (BMI) and neck circumference were noted. Patients completed STOPBANG, Epworth Sleepiness Score (ESS), Functional Outcome of Sleep Quality score (FOSQ) and underwent overnight oximetery. Results: Mean (95% CI)age was 45yrs (38-53),mean BMI 28 kg/m2(26-31)with mean duration of diagnosis 13.5 yrs(7-19.8). Mean reported ESS was 8.7(6.6-10.7) and STOPBANG of 2.3(1.7-2.9). All patients indicated significant impairment on FOSQ. Mean Mallapatti score was 1.8(1.4-2.3),mean neck circumference of 38.2cm (36.6-39.7). Sleep scores co-related poorly with ODI >15/hr. Discussion: SRDB did not account for high FOSQ/ESS in all patient9s ( r=0.007) implying role of disease process in causation. Neck circumference > 17in did not corelate with either EDS or dip rate of >15/hr on overnight oximetry. All patient9s with BMI>30 reported EDS but this corelated poorly with ODI>15/hr. Conclusions: Our results indicate that SRDB does not contribute significantly to EDS in patients with MD.This has potential implications in selecting treatment option (NIV versis Modafinil). Reference 1. Bhat, S etal;2012, Sleep disordered breathing in myotonic dystrophy type 2: Sleep Med,v. 13, p. 1207-8.