BREATHING PATTERN AWAKE AND ASLEEP IN MYOTONIC-DYSTROPHY

Because myotonic dystrophy patients show marked irregularities of brea thing both awake and asleep, variables related to breathing pattern un der both conditions were measured in 11 patients, together with pulmon ary function indices, ventilatory CO2 response and maximal mouth press ures. The aim of the study was to detect and explain a possible interr elationship between daytime and nocturnal irregularity. Awake, patient s demonstrated significantly more variability in tidal volume and resp iratory cycle time than controls. Asleep, periodic breathing occurred during up to 100% of the time spent in light sleep, but not during dee p sleep. A strong correlation was found with age (r = 0.73, p = 0.01). No relationship was found between disturbed breathing awake and aslee p. There was a tendency for increased variability of tidal volume awak e in cases with a decreased ventilatory CO2 response (p = 0.1). The re sults indicate that different mechanisms may be involved in daytime an d nocturnal irregularity. It is hypothesized that brain stem integrati ve functions may be impaired in myotonic dystrophy.