Abstracts

The last ten months we carried out a total of 440 recordings of which more than 200 had a manifold increase of epileptic activity during sleep. The majority of these patients had a seizure disorder, but some had only cognitive and/or behavioural disorders. The purpose of this study was to characterize the epileptic activity and relate it to the clinical diagnosis. All recordings, including at least one night, with epileptic activity during sleep were included. Since many patients had recordings before and after start of drug treatment, only the first recording was included, in total 114. Referrals, and other available information were used for diagnosis. The patients were grouped as having epilepsy, attention deficit (ADHD), autism spectrum disorder (ASD) or Landau-Kleffner syndrom (LKS). Spike index was calculated as the fraction of time when there was less than 3 s between spikes in 10-minutes epochs. The mean age of the patients was 11 years. There was only one patient below the age of five and three above 17. The mean spike wave index for the whole group was 45.6% during slow wave sleep, 15.8% during REM-sleep and 9.4% awake. The mean number of detected spikes was 15872 during sleep. In the patient group with seizures the mean increase in epileptic activity from awake to sleep was 81.4 times. In patients without seizures the mean increase was 51 times (n=16). The difference is not significant (p=0.33). ADHD, ASD and LKS in patients without seizures had a mean increase of 38.1 (n=5), 9.5 (n=2) and 22.9 (n=4) times respectively. The mean inter spike interval during slow sleep was 1.1 s in the seizure group and 2.4 in the non-seizure group (p=0.0034). There was a significant longer inter spike interval in the group without seizures compared to the epilepsy group. This may indicate that higher spike frequency increases the change of clinical seizures. The increase in epileptic activity during sleep was highest in the ADHD group without seizures, but the difference did not reach significance compared to the epilepsy group. The suprisingly high increase in epileptic activity during sleep in the ADHD group warrants further studies. All groups showed large spread that partly reflects the age differences and partly may be due to heterogeneity in the groups.