Hyperventilation is a very effective means of eliciting absence seizures in children with absence epilepsy. Worldwide EEG protocols for routine EEG recording include 3 minutes of hyperventilation. The whole EEG recording, including hyperventilation, is performed with the child lying down on a bed/coach. Our clinical experience suggests that the body position may affect the yield of hyperventilation in provoking the absence event. That is, hyperventilation may be more effective when the child is sitting up, Therefore, children referred for a routine EEG for suspected absence seizures will add 3 minutes of hyperventilation on a sitting position to the routine 3 minutes of supine hyperventilation. At least 5 minutes of rest will be allotted between both procedures.
Patients' caregivers will sign an informed consent form. Patients will randomly be divided into 2 groups: one group will first perform supine hyperventilation followed by sitting hyperventilation; the second group will perform hyperventilation in the opposite order, ie, first sitting up and then in supine position.
