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Epileptiform K-Complexes and Sleep Spindles: An Underreported Phenomenon in Genetic Generalized Epilepsy

Seneviratne, Udaya; Cook, Mark; D'Souza, Wendyl

Journal of Clinical Neurophysiology: April 2016 - Volume 33 - Issue 2 - p 156–161
doi: 10.1097/WNP.0000000000000239
Original Research

Purpose: To study the frequency of epileptiform K-complexes and sleep spindles as well as clinical variables influencing those abnormalities.

Methods: We prospectively performed 24-hour ambulatory EEGs in a cohort of patients with genetic generalized epilepsy diagnosed and classified according to the International League against Epilepsy criteria. Overlapping of epileptiform discharges with K-complexes and sleep spindles was defined as epileptiform K-complexes and epileptiform sleep spindles. The presence of epileptiform K-complexes and sleep spindles was tabulated for each patient, and frequencies were calculated. We performed multiple regression analysis to study the influence of clinical predictors on the occurrence of epileptiform K-complexes and sleep spindles. The predictor variables tested in the model were seizure-free duration, epilepsy duration, genetic generalized epilepsy syndrome, number of antiepileptic drugs, use of sodium valproate, and use of lamotrigine.

Results: A total of 107 patients (37 males and 70 females) were studied. The mean age was 28.5 ± 10.7 years (range, 13–58). Juvenile absence epilepsy was the most common epilepsy syndrome in the cohort (31.8%), followed by generalized epilepsy with tonic-clonic seizures only (26.2%), juvenile myoclonic epilepsy (26.2%), and childhood absence epilepsy (14%). Epileptiform K-complexes and sleep spindles were seen in 65.4% and 10.3% of patients, respectively. None of the clinical variables had any significant impact on the occurrence of epileptiform K-complexes and sleep spindles in our multivariable analysis.

Conclusions: Epileptiform K-complexes are common in the sleep EEGs of patients diagnosed with genetic generalized epilepsy. This underreported phenomenon highlights the important association of arousals and epileptiform discharges in genetic generalized epilepsy.

*Department of Medicine, St. Vincent's Hospital, University of Melbourne, Melbourne, Australia; and

Department of Neuroscience, Monash Medical Centre, Melbourne, Australia.

Address correspondence and reprint requests to Udaya Seneviratne, FRACP, Department of Neuroscience, St. Vincent's Hospital, PO Box 2900, Fitzroy VIC 3065, Melbourne, Australia; e-mail:

© 2016 by the American Clinical Neurophysiology Society