Abstracts

Rationale: Generalized tonic-clonic seizures (GTCs) (generalized motor seizures with loss of awareness or focal seizures evolving to bilateral tonic-clonic) frighten families, are a risk factor for SUDEP and dominate the public’s image of epilepsy. We studied how many children with epilepsy have GTCs and how often they recur.  Methods: We selected 463 children from the prospective Nova Scotia population-based cohort of children with new onset epilepsy and =10 years follow up. Patients had epilepsy onset between 1977 and 1985 and were identified through a central EEG facility with diagnostic confirmation by chart review and personal assessment.  All cases were treated with AEDs and nearly all were followed by a child neurologist. Patients were contacted several times during follow up with seizure types and numbers estimated from direct questioning and chart review.  We selected those with =1 GTC. Children with childhood absence epilepsy were excluded because our coding system failed to document their number of GCTs.   Results: Four hundred sixty-three patients were eligible. Age of onset averaged 6.2±4.8 years and follow up averaged 25.6±5 years. Overall 362/463(78%) had =1 GTC. During follow up, of the 463 patients, 80 (17%) had 1-5 GTCs, 56 (12%) had 6-10, 54 (12%) had 11-20, 70 (15%) had 21-99 and 97 (21%) had >100 GTCs. In 87% of those with GTCs, the first GTC occurred within a year of seizure onset. In patients with focal epilepsies and GTCs, 63% had >1 seizure type compared with 57% with generalized epilepsies (p=ns). The proportion of patients with >20 GTCs in broad epilepsy syndrome groupings was: focal epilepsy 95/235 (40%), JME 11/21 (52%) and “symptomatic generalized epilepsy” 45/73 (62%). Intellectual disability was more common in patients with >20 GTCs compared with those with fewer GTCs (80 (48%) vs 23/192 (12%) pAEDs were “traditional” and compliance was judged to be excellent in most patients based on clinical questioning and AED blood levels. Terminal remission off AEDs occurred in 56% of those with GTCs (mean duration 15±10 years), slightly lower than for the overall cohort (62%). Terminal remission occurred in 84% of those with 1-5 GTCs, 72% with 6-10,  69% with 11-20, 47% with 21-99 and 24% with >99 (p21 GTCs (146/192 (76%) vs 56/157 (38%) p100 GTCs. Conclusions: Nearly 80% of children with epilepsy have GTCs: ~40% have =20, and 20% have >100. Only half of those with >20 GTCs have normal intelligence and remission occurs in only one-third with >20 GTCs compared with three-quarters of those with =20. While this cohort was treated with traditional AEDS, there is no evidence that newer AEDs have greater efficacy, so the diagnosis of epilepsy in childhood is usually followed by significant and often alarming numbers of GTCs. It is not surprising that families and the public fear GTCs even though SUDEP is rare. Funding: No grant support .