Encephalopathy with status epilepticus during sleep: Unusual EEG patterns

• ESES is a well-defined epileptic syndrome, in the category of epileptic encephalopathies.
• ESES syndrome associated with unusual EEG patterns may be variants of this syndrome.
• Epileptic encephalopathy associated with focal ESES should be treated vigorously.

PurposeTo retrospectively analyze the electroclinical characteristics, etiology, treatment, and prognosis of patients with epileptic encephalopathy with status epilepticus during sleep (ESES) with unusual EEG features and to corroborate if this series of patients is part of the ESES syndrome.MethodCharts of 17 patients with typical clinical manifestations of the ESES syndrome with focal ESES of non-REM sleep at onset and during the focal ESES phase, or bilateral synchronic and asynchronic ESES with a symmetric or asymmetric morphology, continuous or subcontinuous and sometimes multifocal paroxysms with or without slow-wave activity during slow sleep seen between 2000 and 2012 were analyzed.ResultsMean patient follow-up from onset was 7.5 years. An idiopathic cause was found in seven patients, a structural cause in eight, and etiology was unknown in the remaining two. The median age at onset of the unusual ESES syndrome was 7 years. During the ESES phase, 15 children developed new seizure types, negative myoclonus was observed in seven patients, positive myoclonus in five, and absences in nine. Six patients had motor impairment, two had auditory verbal agnosia, and two had motor speech impairment. Attention deficit hyperactivity disorder was observed in four, aggressiveness in six, memory deficit in two, and impaired temporospatial orientation in four.The patients with focal ESES in the frontal region showed behavioral disturbances and/or motor deterioration, and in those with temporo-occipital involvement the dominant clinical manifestations were language and/or behavioral disturbances.ConclusionOur patients with typical clinical manifestations of ESES syndrome but with unusual EEG patterns may be variants of this syndrome.