REM sleep physiology and selective neuronal vulnerability in amyotrophic lateral sclerosis

The widespread and relentless progression of skeletal muscle weakness secondary to motor neuronal degeneration in amyotrophic lateral sclerosis (ALS) is all the more striking in the relative preservation of those motor neurons subserving oculomotor function and continence. The molecular and broader physiological basis for selective neuronal vulnerability in ALS remains a subject of intense study and speculation. We note significant similarities with the pattern of muscle involvement associated with rapid eye movement (REM) sleep, raising the possibility of shared motor networks and so novel avenues for study. The stage of normal sleep associated with REM involves a temporary but profound state of motor paralysis during which there is, by definition, preservation of eye movements, and also continence. Respiration enters a more wakeful pattern of …