Background: Epileptiform K-complex is spike/polyspike discharges overlap K-complex. The variable appearance of the K-complex makes the epileptiform abnormality difficult to recognize.

Objective: To recognize and raise attention for epileptiform K-complexes.

Case Report: A 35-year-old man with a history of juvenile absence epilepsy had 2 new onset generalized convulsions. EEG (Electroencephalogram) recorded 95 K-complexes periodically during sleep, 22 of which were epileptiform K-complexes. Small spike and polyspike were superimposed on either the ascending or the descending limb of the slow wave of K-complex. In addition, spike/polyspike-wave discharges were immediately preceding the K-complex to form a polyphasic slow wave with long duration of K-complex.

Summary: In generalized epilepsy, epileptiform K-complexes have superimposed spike/polyspike with sharper morphology and faster frequency than normal intra-K-complex oscillation. Epileptiform K-complexes may also have a relatively higher amplitude and longer duration when pike/polyspike-wave preceding K-complex, distorts the morphology of K-complex. The most helpful recognition of the epileptiform K-complex is the similar morphology of spike/ polyspike-wave recorded during photic stimulation, hyperventilation, or awake period.

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