Understanding the floppy baby.

Muscle tone develops in a orderly sequence through gestation and continues to change after birth. Hypotonia is frequently found in infants, and pathological degrees must be differentiated from normal variations. This distinction is possible if the clinician understands how muscle tone is regulated and modifies his examination to include some special clinical signs. A variety of pathological conditions can influence muscle tone, and hypotonia can be an early and valuable clue to recognizing neuromuscular, CNS, metabolic, and other disease states in this age group.