Abstracts

Rationale: To determine the incidence of epilepsy onset under 2 years, associated structural brain abnormalities and whether cases can be categorized according to the ILAE classification system (2001) at onset. A population based sample was ascertained to minimise the effect of referral bias to specialist centres.Methods: Children aged less than 2 years with new onset epilepsy were ascertained over 13 months from 15 boroughs of North London through notification by paediatricians. Classification based on clinical (patient assessments or anonymised clinical records), EEG and neuroimaging data was undertaken independently by 2 paediatric neurologists. Neuroimages were reviewed by two neuroradiologists, who were unaware of the clinical details.Results: 56 patients (31 boys, mean age of seizure onset 6.3 [range 0.1- 22] months) have been enrolled giving a crude incidence of 62.3 (95% CI: 47.4 – 81.9)/100,000 children under age 2/year. Seizure types were categorised as epileptic spasms (15 children; 28%), focal (24; 43%), generalised (6; 11%), and multiple seizure types in 3 cases (5%) with disagreement in 7(12%) patients. There was agreement on syndrome classification in 36 of 55 cases (65%), which included West syndrome (13), symptomatic or probably symptomatic focal epilepsy (18), idiopathic focal epilepsy (4) and 1 case was not classifiable. Fifty four (96%) underwent neuroimaging: 52 magnetic resonance imaging (MRI), 2 brain computer tomography, 7 both. Images of 49 (90%) children were available for review, including 59 MRI scans (11 repeat scans). Lesions implicated in epilepsy were found in 21 (45%); developmental malformations in 9 (18%) (tuberous sclerosis (2), bilateral polymicrogyria (4), lobar/multilobar focal cortical dysplasia (2) and lissencephaly (1)), acquired lesions (hypoxic ischaemic injuries, inborn errors of metabolism) in 12 (24%) and probable mesial temporal sclerosis in 1. Ten patients (21%) had non-specific structural abnormalities (lack of white matter bulk, thin corpus callosum, delayed myelination and arachnoid cysts).Conclusions: The crude incidence of epilepsy is 62/100.000 children under age 2 /year. Spasms and focal seizures are the most common seizure types. Diagnosis of syndrome can be difficult with disagreement on epilepsy syndrome diagnosis in a third of cases. Yield of magnetic resonance imaging is high justifying routine imaging in all infants with new onset epilepsy.