Changes in blood flow of the middle cerebral artery during absence seizures.

Blood flow velocities (BFVs) of the middle cerebral artery were measured by transcranial Doppler blood flowmeter in 2 patients with childhood absence epilepsy; a total of 8 absence seizures were recorded. BFV began to decrease 7-9 sec after the appearance of diffuse bilateral 3 Hz spike-and-wave bursts on electroencephalography, reaching the trough 0-8 sec after the disappearance of spike-and-wave bursts which was followed by BFV recovery with rebound phenomenon. BFV then returned to the pre-ictal value within 1 min after the seizure ended. Pulsatility index increased in accordance with BFV decrease.