Movement zyxwvutsrqponmlkji Disorders zyxwvutsrqponm Vol. 8, No. 2, zyxwvutsrqpon 1993, zyxwvutsrqponm pp. 191-194 zyxwvutsrqpon 0 1993 Movement Disorder Society Benign Neonatal Sleep Myoclonus: Clinical Video-Polygraphic Recordings Features and Matteo Di Capua, Lucia Fusco, Stefan0 Ricci, and Federico Vigevano Section of Neurophysiology, Bambino Gesu Children’s Hospital, National Medical Research Institute, Rome, Ztaly Summary: Benign neonatal sleep myoclonus is a syndrome characterized by the occurrence of repetitive myoclonic jerks of the extremities exclusively during non-rapid eye movement sleep in the early life of healthy newborns. No etiological factors are present. The onset is within the first 15 days of life with spontaneous disappearance within 3-4 months. These myoclonic events are commonly diagnosed as epileptic seizures. We observed 12 newborns with this clinical pattern; the follow-up ranges from 12 to 60 months. Long-term vid- eopolygraphic electroencephalographic (EEG) monitoring demonstrated nor- mal EEG activity, thus confirming that these unusual events were nonepilep- tic. Key Words: Neonatal myoclonus-Nonepileptic disorder-Non-rapid eye zyx - movement sleep. Myoclonus has been defined as a brief, shocklike, involuntary movement caused by muscular contrac- tions (positive myoclonus) or inhibitions (negative myoclonus) arising from the central nervous system (1). In a newborn, myoclonic manifestations are usually warning symptoms, because they may indi- cate the presence of brain damage or the onset of a progressive encephalopathy . The repetitive jerking occurring exclusively dur- ing quiet sleep [non-rapid eye movement (NREM) sleep] in a healthy newborn and described here is a rarely reported harmless phenomenon generally identified as benign neonatal sleep myoclonus (BNSM) (2-6). Prompt recognition of this benign form of myoclonus will avoid unnecessary diagnos- tic tests and possibly harmful treatment. METHODS Between January 1986 and February 1990, 12 newborns with BNSM were referred to us for in- vestigation of convulsions (Table 1). All were born Videotape segments accompany this article. Address correspondence and reprint requests to Dr. Matteo Di Capua, Section of Neurophysiology, Bambino Gesh Children’s Hospital, Piazza S. Onofrio, 4, 00165 Rome, Italy. at term after a normal pregnancy and delivery; their birth weights ranged from 2,950 to 4,500 g. None had a family history of convulsions, epilepsy, or sleep disturbances. Jerks first appeared during sleep in these infants during the early neonatal stage: the ages at onset of myoclonus ranged from 1 to 15 days (average 6.3). All the parents reported that when they took the baby in their arms, as soon as the baby woke up the shaking stopped. The my- oclonus occurred daily, always during sleep. Neurological cerebral ultrasound and routine he- matochemical findings were normal in all cases. Videopolygraphic monitoring recordings were obtained during wakefulness and active and quiet sleep. Sleep recordings lasted 22 h. Polygraphic studies included electroencephalogram (EEG), electrooculogram, pneumogram, and electromyo- graphic (EMG) recordings from surface electrodes on the right and left biceps. The 12 infants were observed for periods ranging from 12 to 60 months (average 33). In seven cases the frequency and intensity of myoclonus progres- sively increased, reaching a peak between 15 and 35 days (average 21.6), thereafter gradually declining. The phenomenon disappeared within 3&135 days of age (average 77.5). Psychomotor development was normal in all 191