Relation of spasms and myoclonus to suppression-burst on EEG in epileptic encephalopathy in early infancy.

PURPOSE: This study was intended to clarify the relation between spasms in series and a suppression-burst (SB) EEG pattern which have a common nature of repetitive bursting activity in epileptic encephalopathy in early infancy.

METHODS

The ictal EEG traces of spasms were temporally compressed and expanded to study the beginning and ending phases of series along with their spectral analysis in two patients with Ohtahara syndrome (OS) and one with early myoclonic encephalopathy (EME). The EEG bursts associated with myoclonus were also investigated.

RESULTS

A mutual transition was indicated between the ictal activity of spasms and the bursts in the peri-series SB on EEG. Gamma rhythm was detected in common in the ictal activity and the peri-series and interictal bursts on EEG, and also in the bursts with myoclonus.

CONCLUSION

The relation between the ictal activity of spasms and SB on EEG was shown to be close. The generative mechanisms of spasms and myoclonus might be linked to the bursting tendency intrinsic to immature brain function.