The Circadian Rhythm of Typical Absence Seizures - The Frequency and Duration of Paroxysmal Discharges

Abstract

Twelve patients with typical absence seizures, aged five years two months to 10 years, were examined to clarify the circadian rhythm of 3 c/s spike-and-wave paroxysms (s-w paroxysms), by means of video-electroencephalography with telemetry. S-w paroxysms combined with clinical symptoms and continuing for more than four seconds were fewer during the afternoon than the morning and, moreover, during sleep. The correlation ratio between the frequency and duration of s-w paroxysms was r=-0.74, which was statistically significant (p<0.02). The duration of s-w paroxysms evoked by hyperventilation or photic stimulation did not differ from that of spontaneous s-w paroxysms. The s-w paroxysms were shorter and deformed in sleep. Therefore, the observation of typical absence seizures during the morning should be regarded as important. In patients with modified s-w paroxysms during sleep, it is important that electroencephalographic recording with stimulation, such as hyperventilation, is performed sufficiently.

Key words

Circadian rhythm - Absence seizures - Ambulatory electroencephalography