Risk factors predicting intractability in focal epilepsy in children under 3 years of age: A cohort study

Background: Focal onset epilepsy carries a higher risk of intractability than generalized onset epilepsy. Knowledge of the risk factors of intractability will help guide the treatment of children with focal epilepsy. In addition to risk factors present at initial diagnosis, the evolution of clinical and electroencephalographic features may also play a role in predicting intractability. Methods: A prospective cohort study was done on children aged one month to three years with newly diagnosed focal epilepsy. Initial treatment of carbamazepine was given according to a standard protocol after assessment of clinical manifestations, neurologic and developmental status, EEG, and brain MRI. Depending on response to therapy, subjects may also receive valproic acid or phenobarbitone following the protocol. Follow-up was done in the second week and every month thereafter. At the end of the study period, seizure type was re-assessed and a repeat neurological and developmental examination and EEG was obtained to evaluate the role of clinical and EEG evolution in predicting intractability. Results: Out of 71 subjects, 21 (29.6%) had intractable epilepsy at the end of the study period. Age of onset (p = 0.216) and neurological status (p = 0.052) were not associated with intractable epilepsy. On logistic regression analysis, evolution of seizure type (p < 0.001; RR 56.45; 95%CI 6.56 to 485.85) and evolution of background EEG rhythm (p < 0.001; RR 56.51; 95%CI 2.77 to 1152.16) were significantly associated with intractable epilepsy. Conclusions: Changes in seizure type and baseline EEG rhythm may predict intractability in children one month to three years of age with focal epilepsy.