CSA 5 – Answer

Abnormal beta activity – the raw EEG is in keeping with beta activity (frequency – 24 Hz). As the patient is deeply sedated this beta activity is abnormal (beta activity normally occurs in awake patients). Common causes of abnormal beta activity in PICU include underlying brain injury and as in this case the use of midazolam for sedation. The bolus of thiopentone caused brief suppression of brain wave activity followed by return of the abnormal beta activity secondary to the midazolam. This can be differentiated from seizure activity by the appearance of the raw EEG and also by the fact that only the frequency is increased and not the power (seizure activity is sudden onset increase in both frequency and power).