Focal seizures versus epileptic spasms in children with focal cortical dysplasia and epilepsy onset in the first year

Purpose: Focal cortical dysplasia (FCD) has been recognized as one of the most frequent causes of drug resistant epilepsy, especially in children. In infancy, onset of FCD-related epilepsy is substantially characterized by epileptic spasms (ES) or focal seizures. Which elements pertaining to the FCD are responsible for the onset of one type of seizure over the other is still unclear. Purpose of our study was to compare the characteristics of FCDs in terms of lateralization and site in patients with epileptic spasms versus patients with focal seizures.

Methods: We retrospectively reviewed data from 41 patients with FCD related epilepsy with onset during the first 14 months of life. Seizure semeiology and drug resistance were analyzed, as were age at onset and FCD site and lateralization.

Results: Twenty-one children had focal seizures, 11 had ES and nine had focal seizures followed by ES. Mean age at onset was respectively 8.2, 5.1 and 1.8 months. Drug resistance was present in respectively 38.5%, 34.6% and 26.9% of children. Among patients with only ES, 90.9% had an exclusively frontal FCD localization, versus 42.9% of patients with focal seizures and 11.1% of patients with focal seizures followed by ES. FCD lateralization was right sided respectively in 47.6%, 81.8% and 66.7% of patients.

Conclusions: Frontal lobe localization of FCDs was closely associated with ES (p=0.001). Moreover we also found that patients with focal seizures followed by ES had a significantly earlier age at onset compared to patients with focal seizures only (p<0.001). The association between ES and right-sided FCD lateralization, even if numerically suggestive, did not reach statistical significance (p=0.16). There was no significant association between seizure type and drug resistance (p=0.08).