Ultradian characteristics of spontaneous seizures discharges recorded by radio telemetry in man

Abstract

Twenty-four hour EEG records were recorded by radiotelemetry during free behavior from five patients with seizures for a total of 18 days and nights. Quantitative measurements of duration of epileptiform bursts, frank seizures and inter-spike and inter-seizure intervals were made from magnetic tape and ink polygraph records. Total consecutive spikes per 4 min over 24 h were enumerated automatically by a specially designed spike recognition unit. Proportional relationships were demonstrated between seizure length and pre- and post-seizure intervals. A broad or quasi normal distribution was found for diurnal seizure and interval durations in contrast to a random (Poisson) distribution for corresponding nocturnal ictal events. A relatively constant inter-ictal spike rate, interrupted every 80 to 120 min was shown for most patients during both day and night. Nocturnally, the period of spike interruption coincided with rapid eye movement (REM) sleep, and spike recurrence with slow wave sleep. A tendency for clinical ictus to occur in relation to the REM periods was apparent.