Features of the K-complex waves in refractory nocturnal frontal lobe epilepsy

Abstract

To investigate the features of the K-complex (Kc) in refractory nocturnal frontal lobe epilepsy (NFLE) and its relationship with spike discharges (Sds) and clinical seizures. Long-term video-electroencephalographic (VEEG) monitoring was used to collect Kc data from NFLE patients and age- and sex-matched controls. We compared the morphological and frequency changes in Kcs between the intractable NFLE group and the control group. Also, the morphological changes in Kcs with Sds and seizures were compared with the other Kcs in NFLE patients. In the NFLE group, frequency, amplitude, and rising slope (except duration) were higher than in the control group. Out of the 30 seizures recorded, nine (30%) commenced after a Kc. These Kcs had higher amplitudes than the other Kcs in the NFLE group; there was no difference in duration or rising slope. Additionally, 28 (13.86%) of 202 Kcs of the NFLE group occurred in conjunction with Sds; there were no obvious morphological differences compared with other Kcs. Kc activity increases in NFLE, especially prior to a clinical seizure. This reflects an unstable sleep condition, which suggests a correlation between Kc and epileptic activities including seizures and Sds.