Risk factors of cognitive impairment in pediatric epilepsy patients with focal cortical dysplasia.

OBJECTIVE: The purpose of this study was to identify the risk factors of cognitive impairment in pediatric epilepsy patients with focal cortical dysplasia (FCD).

METHODS: 77 patients with histopathologically confirmed FCD were studied. The statistical relationship between cognition levels and clinical factors at presurgical evaluation was analyzed. Cognitive function was evaluated by development quotient or intelligence quotient (DQ-IQ).

RESULTS: Ages at seizure onset were younger than 15 years (mean ± SD; 5.0 ± 4.2 years). Mean disease duration was 14.5 ± 8.5 years. Mean age at pre-surgical DQ-IQ evaluation was 34.8 ± 10.7 years. Mean DQ-IQ was 60.5 ± 20.5, and 41 of 77 (53.2%) patients had mental retardation (DQ-IQ < 70). Younger seizure onset and seizure clustering were significantly associated with lower DQ-IQ (p < 0.001). A multiple regression study identified higher seizure frequency pattern, a history of epileptic spasm and status epilepticus as aggravating factors of DQ-IQ decline (R2  = 0.63, p < 0.001). On the other hand, the risk was decreased in patients with habitual focal aware seizure and transient seizure-free periods up to 6 months in the course of epilepsy. FCD location (FCD site, extent of radiological lesion and laterality) and histopathology of FCD did not affect DQ-IQ.

CONCLUSIONS: Our study suggests that seizure characteristics including higher seizure frequency pattern, a history of epileptic spasm, status epilepticus, seizure clustering and early onset of seizure are risk factors of cognitive impairment in FCD patients.