Abstracts

Dyshormia or epileptiform spikes occurring within K-complexes has been described in patients with generalized epilepsy, with one study reporting that generalized spikes occurred frequently in association with K-complexes. We report the rate and laterality of focal dyshormia in localization-related epilepsy. Pre-surgical or diagnostic long-term video-EEG results of 40 consecutive patients with epilepsy (13 patients with right temporal lobe epilepsy, 20 patients with left temporal lobe epilepsy, and 7 patients with frontal lobe epilepsy) were reviewed. Sleep samples were reviewed and the numbers of K-complexes, spikes and spikes within K-complexes were recorded. The comparison group consisted of 40 consecutive patients with non-epileptic events who were monitored with long-term video EEG. Focal dyshormia occurred in 2 of 13 (15%) right temporal lobe epilepsy patients, 6 of 20 (30%) left temporal lobe patients and 3 of 7 (42%) extratemporal lobe epilepsy patients. In most patients with focal dyshormia, spikes occurring during K-complexes were relatively rare.
The epileptiform activity occurred ipsilateral to the primary epileptogenic zone in each case. Not only did more patients with frontal lobe epilepsy have focal dyshormia but the percentage of K-complexes with associated focal epileptiform activity tended to be higher in these patients than in patients with temporal lobe epilepsy. We identified focal dyshormia, or spikes occurring during K-complexes, in patients with localization-related epilepsy. The sharply contoured components of K-complexes or associated sleep spindles may obscure focal spikes within K-complexes. Nevertheless, K-complexes may be associated with focal epileptiform discharges. Several authors suggested that dyshormia occurs only in patients with primary generalized epilepsy. We report focal dyshormia occurring ipsilateral to the primary epileptogenic zone, associated with localization related epilepsy. Given the predilection of the epileptiform discharges associated with K-complexes to occur ipsilateral to the side of ictal onset, the presence of focal dyshormia may assist in the identification of the primary epileptogenic zone. In general, there was a trend toward more K-complexes being associated with spikes in frontal lobe epilepsy than in temporal lobe epilepsy.
Malow et al. reported the presence of sleep spindles recorded from the hippocampus and the association with epileptiform activity in one patient. The association of K-complexes with epileptiform activity may also represent an effect of temporal modulation of the typical features of stage II sleep.