Migration of epileptic spike foci in encephalograms may correlate with a better outcome in pediatric epilepsy

Epileptic spike foci in children can be fixed in specific brain regions or migrate over time. We analyzed 969 encephalograms from 463 epileptic children to determine outcome differences between those with fixed foci (FF) and those with migrated foci (MF) on at least three encephalograms over 3 years. All epileptic spike foci were classified as frontal, temporal, central, parietal, or occipital. Migration directions were divided into anterior, posterior, lateral, and unclassified. Seventy-nine cases met the inclusion criteria: 24 (30%) FF and 55 (70%) MF. More patients in the FF than in the MF group required multiple antiepileptic drugs (P = 0.004), and had abnormal image findings (P = 0.014), mental retardation (P = 0.035), and worse seizure control (P = 0.047). Seizure frequency (P = 0.007; correlation coefficient = 0.56) and the number of prescribed drugs (P = 0.047; correlation coefficient = 0.372) were more significant in the FF group than in the MF group. When we compared only whether the cases were symptomatic or cryptogenic, we found the same outcome trends. In comparisons of only idiopathic epileptic patients, the FF group had non-significantly different outcomes compared with those in the MF group. When we compared 16 cases of benign childhood epilepsy with centrotemporal spikes (BECTs) and 8 Panayiotopoulos syndrome (PS), the cases with BECTs had more FF (38% vs. 0%, P = 0.03). We conclude that outcomes may not correlate as well in FF cases as they do in MF cases. Idiopathic epilepsy warrants more study.