Electrical status epilepticus of sleep (ESES) and continuous spike and waves during slow wave sleep (CSWS) both describes a dramatic increase in interictal activity during sleep. ESES occurs when baseline epileptiform discharges are greatly activated by sleep and seen in >85% of the sleeping record.
Landau–Kleffner syndrome (LKS), affects 3 to 9-year-old children who were previously in good health. The first clinical sign is dysphasia (speech difficulty), which progressively worsens. Speech becomes progressively less intelligible and is eventually limited to only a few words.Hyperactivity and personality changes may appear as the aphasia worsens. About two thirds of patients have seizures of various types, including myoclonus, partial motor, akinetic/atonic, atypical absence, and GTC’s. The EEG in LKS is characterized by abundant epileptiform activity that is extremely variable in both location and volume. In the early stages, epileptiform activity may appear only in sleep. As the disease progresses, EEG abnormalities change considerably in terms of location, abundance, and pattern. Eventually, spikes and spike-wave discharges become continuous, resulting in an appearance of “electrographic status epilepticus”. This EEG feature is like that seen in the syndrome of continuous spike and wave during slow-wave sleep (CSWS). LKS and CSWS overlap in both clinical and electrographic features.