In Billiard's (1982) study of 127 patients, 9.4% had sleep-related complex partial seizures. In a study of 50 patients with sleep-related complex partial seizures, Cadilhac (1982) found that 32 patients had seizures in NREM sleep, 8 in REM sleep, and 10 in both states. However, in a study of 10 patients with a diagnosis of mesial temporal lobe epilepsy, Montplaisier (1985) found that none of these patients had seizures in NREM sleep. In a study of 15 patients with temporal lobe epilepsy, only 7 of the 67 seizures (10.9%) occurred in sleep (Crespel et al., 1998). All the seizures occurred during stage 2 NREM sleep, except for one seizure that occurred from stage 3-4 NREM sleep. Quigg and colleagues (1998) studied the time of day when seizures occurred in patients with mesial temporal lobe epilepsy and found the majority of seizures happened during the waking hours with a peak incidence at 3 p.m.
In terms of the presence of the IEA, most studies of temporal lobe epilepsy have found that there is an increase in interictal epileptiform discharges in NREM sleep with a decrease in REM sleep. There appears to be a maximal peak in the rate of spikes occurring in stage 2 or stage 3-4 NREM sleep (Lieb et al., 1980; Rowan, 1982; Rossi, 1984). In patients with temporal lobe epilepsy, spikes were found in 53% in stage 1, 95% in stage 2, 98% in stage 3, and in all patients in whom stage 4 was recorded (Sammaritano et al., 1991). The spike frequency was highest in the deepest stage of sleep (3 or 4). The spike frequency was greatest in NREM sleep in 85% of patients and in REM in 12.5% of patients. In addition, the extent of the distribution of the electrical field of the unilateral foci was studied as a function of the sleep state. It was found that the extent of the electrical field increased in more than 75% of the spikes in NREM sleep compared with the wake state. In the patient's EEG demonstrated in Figs. 1.4A and 1.4B, unilateral focal sharp waves were seen in the left posterior temporal region while awake (Fig. 1.4A), and bilateral posterior temporal sharp waves occurred during sleep (Fig. 1.4B). In REM sleep, Sammaritano (1991) reported a restriction of the electrical field of the epileptiform activity. In 53% of the group of patients studied, spike foci that were not seen in the awake state were activated in NREM sleep. In contrast to this in REM sleep, 42.5% of patients showed disappearance of foci observed. Depth electrode recording studies have also shown maximal spiking rates in NREM sleep and decrease in REM sleep (Lieb et al, 1980). Restriction of the field of distribution of the interictal discharges during REM sleep observed by Sammaritano was previously reported by Montplaisier (1985). In the study of Malow and colleagues (1997), they determined log delta power (LDP) that was computed by the fast Fourier transform and then used this as an indicator of the depth of sleep. They studied eight pa-
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