Unknown. If strict criteria apply (generalized tonic-clonic seizures (GTCS) only), this may be very small (0.9% of idiopathic generalized epilepsies (IGEs)) but others give a prevalence of 13% to 15% among IGEs.
Age at onset
6 to 47 years (peak 16 to 17 years); 80% have their first GTCS in the second decade of life.
Males (55%) slightly predominate, probably because of alcohol exposure and sleep habits.
Neurological and mental state
Genetically determined. Linkage to EJM1 locus for GTCS on awakening but not with GTCS at other times.
All patients suffer from GTCS. Only IGE with GTCS on awakening has been extensively studied, with GTCS occurring within 1 to 2 hours after awakening from sleep. GTCS may also occur during relaxation or leisure.
Overall, GTCS occur on awakening (17% to 53% of patients), diffusely while awake (23% to 36%) or during sleep (27% to 44%) or randomly (13% to 26%).
Sleep deprivation, fatigue, and excessive alcohol consumption.
Usually normal background, with generalized discharges of spike/multiple spike waves in half of patients with GTCS only and 70% of those with additional mild absences or myoclonic jerks. Focal EEG abnormalities, in the absence of generalized discharges, are rare. 13% show EEG photosensitivity.
Myoclonic jerks and mainly brief phantom absences are revealed with video-EEG during generalized discharges of spike/multiple spike waves.
IGE with GTCS on awakening is probably lifelong with high (83%) incidence of relapse on withdrawal of treatment. Characteristically, the intervals between seizures become shorter with time, the precipitating factors less obvious, and GTCS may become more random (diurnal and nocturnal), either as a result of the evolution of the disease or drug-induced modifications.
Mainly from other IGEs, which share the same propensity to GTCS on awakening. Symptomatic and focal epileptic seizures with secondarily GTCS which may also occur, predominantly on awakening.
Avoidance of seizure precipitants.
For GTCS only, valproate, lamotrigine, levetiracetam, phenobarbital, topiramate, carbamazepine, phenytoin or oxcarbazepine can be considered. AEDs in italics are not recommended if patients also have absences or myoclonic jerks.
*Expert opinion, please check FDA-approved indications and prescribing information
This page was adapted from:
The educational kit on epilepsies
The epileptic syndromes
By C. P. Panayiotopoulos
Originally published by MEDICINAE
21 Cave Street, Oxford OX4 1BA
First published 2006 and reprinted in 2007
Reviewed and revised June 2008 by Steven C. Schachter, MD
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