To the Editor.
—Movement disorders in infancy may indicate a serious underlying disturbance of the CNS. Coulter and Allen1 described three infants with jerking of the limbs during sleep, which they termed "benign neonatal sleep myoclonus." They stressed the need for accurate diagnosis because of the associated excellent prognosis.We recently observed two siblings with this condition. In the older child, rhythmic twitching of the limbs began on the fifth day of life and persisted intermittently during sleep until he was 9 days old. This twitching never recurred, and his development, at age 2.5 years, was normal. His younger sister had similar episodes from 7 days to 5 weeks of age. The rhythmic twitching of all four limbs occurred only during sleep and ceased if the child was aroused. Her neurologic examination results and developmental status were normal at 4 months of age. Both children had normal EEGs.