Sleep disorders and diaphragmatic function patients with amyotrophic lateral sclerosis

In amyotrophic lateral sclerosis (ALS), the progressive loss of upper and l ower motor neurons leads to respiratory failure, often with predominant dia phragm dysfunction, and death. Because the diaphragm is the only active ins piratory muscle during rapid eye movement (REM) sleep, there is a high theo retical risk of respiratory disorders during REM sleep in patients with ALS . To assess this hypothesis, we studied sleep characteristics (polysomnogra phy) in 21 patients with ALS, stratified according to the presence or absen ce of diaphragmatic dysfunction. Diaphragmatic dysfunction was defined as a n absent or delayed diaphragm response to cervical or cortical magnetic sti mulation, abdominal paradox, or respiratory pulse (Group 1, 13 patients). T hese patients did not differ in age, clinical course, or form (bulbar or sp inal) from the eight others, who did not have diaphragmatic dysfunction (Gr oup 2). REM sleep was reduced in Group 1 (7 +/- 7% of total sleep time; mea n +/- SD) and normal in Group 2 (18 +/- 6%, p = 0.004). Apneas or hypopneas were rare in both groups. In Group 1, REM sleep was absent or minimal (les s than 3 min) in five patients. An unusual and remarkable preservation of p hasic inspiratory sternomastoid activation during REM was associated with l onger REM sleep duration in six of the other patients with diaphragmatic dy sfunction. Median survival time was dramatically shorter (217 d) in Group 1 than in Group 2 (619 d, p = 0.015).