Idiopathic generalized epilepsies with pure grand mal: clinical data and genetics.

OBJECTIVE: To analyze the clinical features and family history of patients with idiopathic generalized epilepsy (IGE), with pure grand mal (GM), divided into epilepsies with GM occurring exclusively on awakening (GMA) and random GM (RGM).
METHODS: We studied retrospectively 98 patients from a large epilepsy outpatient clinic. All patients had a full clinical examination and computed cerebral tomography scans (CCT) or magnetic resonance imaging (MRI) when feasible. We analyzed seizure type, seizure frequency, provocative factors, prognosis, electroencephalography (EEG) findings and family history.
RESULTS: Sixty-eight patients had GMA and 30 had RGM. The mean age at seizure onset was 16.6 years (+/-6.3 S.D., range: 5-41) and 16.7 years in those with RGM (+/-7.5 S.D., range: 4-42, NSD). Patients with GMA had a longer course of active epilepsy (median 8.5 years) compared to RGM (median 2 years). Seizure-provoking factors, especially sleep deprivation, were significantly (P=0.001) more common in patients with GMA (52/68, 77%) than in the group with RGM (13/30, 43%). Of all patients, 23% (23/98) reported first degree relatives with seizures or epilepsy. Pure GM was found in 41% (12/29) of affected first degree relatives, other idiopathic generalized epilepsy syndromes were less frequently observed (4/29, 14%). The concordance rate was high within the syndrome - none of the patients with RGM had an affected relative with GMA and vice versa only two of affected relatives of GMA patients had RGM.
CONCLUSION: GMA seems to be associated with a longer duration of active epilepsy, a higher relapse rate and a stronger tendency to be precipitated by seizure provoking factors. The different concordance rates between the syndromes suggest a genetically different background.