Abstracts

Rationale: Automatisms are common in absence seizures. This study examines the frequency and nature of automatisms in new onset absence seizures and the influence of state of arousal, provocation, age and epilepsy syndrome. Methods: Children presenting with untreated absence seizures were studied using video-EEG recording. Each seizure was analysed for the presence and characteristics of automatisms. The influence of the following variables on the presence of automatisms was analysed: state of arousal (awake, drowsy, sleep), provocation (hyperventilation, photic stimulation), age and epilepsy syndrome. Results: Automatisms were observed in 163 of 405 (40%) seizures in 53 of 70 (76%) children. Automatisms were more likely in longer seizures and during hyperventilation. Only 23% of spontaneous awake seizures had automatisms. The automatisms tended to be similar for an individual child, however, automatisms were not consistently present in all of their seizures. There was no effect of age, epilepsy syndrome or state of alertness on the presence of automatisms. Conclusions: The high frequency of automatisms during routine EEG recordings is predominantly due to the effect of hyperventilation. Their preponderance during longer seizures may relate to opportunity for automatisms to occur. The characteristic pattern of automatisms in absence seizures suggests a reactive phenomenon to internal and external stimuli.