Benign neonatal sleep myoclonus

Abstract

Benign neonatal sleep myoclonus (BNSM), first described in 1982 by Coulter and Allen [1], is the non-epileptic condition most frequently confused with epileptic seizures during infancy. The etiology is uncertain: transient dysfunction of the serotoninergic system, a benign disturbance of the brainstem reticular activating system involved with initiation and synchronization of sleep and a genetic predisposition have been suggested by some authors. However none of these mechanisms has been proved [1,2]. The prevalence is also unknown, but it is thought that the condition is under-recognized. It was first described in three boys and in most subsequent publications, the condition was more commonly described in boys. Very recently, it has been shown that BNSM is extremely frequent in the newborn offspring of opiate-dependent mothers [3]. Myoclonic jerks usually present within a few days of birth. In a detailed study of 38 patients with BNSM the jerks appeared within the first 16 days, (median 3 days) and remitted in the first 10 months (median 2 months) of life [4]. It is usually said that the jerks disappear by the age of 3 months, but Egger et al. [5] demonstrated that the condition could persist for months and years. In the first description of BNSM myoclonus was reported to be bilateral, synchronous, and to mainly involve the distal parts of the upper extremities, with flexion of fingers, wrist, and elbow [1]. It is usually de-