OBJECTIVE: Bilateral, symmetric and synchronous generalized epileptiform activity is considered to be the typical electroencephalographic (EEG) abnormality in @entity74 ( @entity74 ). We sought to study atypical EEG abnormalities in a systematic way based on 24-h ambulatory EEG recordings. METHODS: The diagnosis of @entity74 was validated and classified into syndromes according to the International League against @entity302 . All @entity1 underwent 24-h ambulatory EEG recording. @entity302 were counted and detailed information was entered into an electronic database. Amplitude asymmetry, focal onset/offset of @entity7965 , focal discharges, atypical morphology and generalized paroxysmal fast rhythm were defined as @entity854 . RESULTS: Of the total of 120 @entity1 , 107 had abnormal EEGs, of which 66.4% had at least one atypical @entity302 on EEG. Atypical morphology was the most frequent abnormality in 93.4% of @entity1 , followed by amplitude asymmetry (28.0%), focal discharges (21.5%), focal onset of @entity7965 (13.1%), focal offset of @entity7965 (8.2%) and generalized paroxysmal fast rhythm (1.9%). The analysis of individual discharges revealed that 76% of @entity7965 were of atypical morphology. Significant associations were found between (a) amplitude asymmetry and state of arousal (p<0.001) as well as @entity410 -free duration (p 0.013); (b) atypical morphology and state of arousal (p<0.001). CONCLUSION: In @entity74 , there are both common and rare atypical @entity302 that may vary according to the state of arousal and @entity410 -free duration. SIGNIFICANCE: Awareness of these variations is important to avoid misdiagnosis.

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@entity1 :: ('9606', 'Species') :: ['participants', 'patients'] @entity410 :: ('MESH:D012640', 'Disease') :: ['seizure'] @entity854 :: ('MESH:D018376', 'Disease') :: ['atypical abnormalities'] @entity7965 :: ('MESH:D006457', 'Disease') :: ['paroxysms'] @entity302 :: ('MESH:D004827', 'Disease') :: ['Epilepsy criteria', 'epileptiform EEG abnormalities', 'epileptiform abnormality', 'Epileptiform discharges'] @entity74 :: ('MESH:D030342', 'Disease') :: ['GGE', 'genetic generalized epilepsy']
@entity854 :: (MESH:D018376,Disease) :: ['Atypical EEG abnormalities']
