Benign neonatal sleep myoclonus was diagnosed in 10 infants at the Children’s Hospital, Winnipeg, Manitoba. The neonates were referred for assessment of seizures. The myoclonus increased with gentle restraint and in 2 patients it worsened in spite of anticonvulsant therapy. None of the clinical events was associated with EEG seizure phenomena. All infants were neurodevelopmentally normal between the ages of 4 months and 5 years. The myoclonus remitted by age 6 months in all but 2 infants. [1]

COMMENT. Benign neonatal sleep myoclonus has the following characteristics: 1) neonatal onset, 2) myoclonic jerks only during sleep, 3) abrupt and consistent cessation with arousal, 4) absence of EEG seizure activity and 5) good prognosis. This entity must be distinguished from benign familial neonatal seizures and anticonvulsants should be withheld. The condition should also be differentiated from neonatal hyperekplexia which is characterized by massive jerks in response to sudden tactile and acoustic stimuli and long lasting myoclonic jerks closely resembling epileptic seizures. [2]

Benign myoclonic epilepsy of early childhood reported in 20 children from Riyadh, Saudi Arabia [3] was considered a phenotype differing only in the age of onset, but sharing the same genotype as benign infantile myoclonic epilepsy and juvenile myoclonic epilepsy.

Benign myoclonus of early infancy was reported in 6 cases from Milan, Italy [4]. The sudden onset of monoclonic jerks mainly involving the trunk and upper limbs, normal developmental milestones, absence of EEG abnormalities and self limited course were consistent with the diagnosis as described initially by Lombroso and Fejerman.