Benign myoclonus of early infancy is a paroxysmal phenomenon in neurologically healthy infants with onset in the first year of life and a benign self-limited course. It was first described by Lombroso and Fejerman (1977) with the presentation of 16 cases based mainly on anamnestic features. The first polygraphic study on BM was reported by Dravet et al. (1986), who decided to call the phenomenon benign non-epileptic infantile spasms because of the close relationship with the clinical picture of epileptic spasms of West syndrome. We illustrated the clinical and neurophysiological study of 5 patients with BM (Pachatz et al., 1999) and showed that the so-called myoclonus is not a myoclonus in neurophysiological terms, and that it is also clearly distinguishable from epileptic spasms at electromyography and even from a clinical point of view. Since that report, we obtained additional clinical and neurophysiological data in another three children, confirming that BM in its most typical form is characterized by a brief shudder-type axial motor manifestation, which can superimpose a series of other paroxysmal motor phenomena.
Clinical and video-polygraphic findings from a recent series
Between the years 1994 and 1999 we studied eight children, three girls and five boys, at the Division of Neurology, Bambino Gesù Children's Hospital, Rome, Italy, using video-EEG recording in all eight patients and polygraphic recording in four of eight cases. Scalp electrodes were placed according to the International 10–20 System. Polygraphic recordings included surface electromyographic (EMG) recording from the two deltoid muscles, channels for respirogram and electrocardiogram.
In all patients we studied, family or personal history was negative for neurological pathologies.