NEONATAL SLEEP MYOCLONUS – A BENIGN SHAKING DURING NEONATAL PERIOD

Objectives: Benign neonatal sleep myoclonus (BNSM) is still considered as an under recognized, non-epileptic condition during early life. The clinical picture is well known however, there is lack of literature and it is often labeled as seizures even by highly experienced staff. The diagnosis is usually made “per exclusionem”, and all examinations are normal. We report this entity in eight newborns, referred to us for evaluation of seizures.

Methods: We studied eight term infants, referred for assessment of seizures but were considered to have BNSM after thorough medical history, clinical observation, neurological evaluation and polygraphic and/or EEG recordings. All had normal antenatal and delivery history and no history of epilepsy. The myoclonic jerks started between third and 13th day of life. The description of events was obtained from parents, nurses, physicians, or home-video recordings as myoclonic jerks of focal, multifocal or bilateral synchronous and symmetrical distribution. Each jerk lasted few seconds but tended to recur during up to 20 minutes' period. All jerks occurred only during sleep, never appeared in facial muscules and could not be stopped by gentle restraint but with awakening of the child. Three infants were unsuccessfully treated with anticonvulsant therapy. Myoclonic jerks remitted between two and seven months of age and all infants were neurodevelopmentally normal on follow-up.

Conclusion: We believe that BNSM during neonatal and early infantile period occurs appears immediately after a newborn or a small infant fall asleep (REM sleep). Finally we can say that the diagnosis depends entirely on the clinical grounds and all persons working in the neonatal units should be aware of this entity and should recognize and avoid unnecessary investigations and treatment.