Repeated seizures induce prefrontal growth disturbance in frontal lobe epilepsy

Background: The possible consequences of seizures in the immature brain have been the subject of much conjecture. We prospectively measured frontal and prefrontal lobe volumes using three-dimensional (3D) magnetic resonance imaging (MRI)-based volumetry in patients with frontal lobe epilepsy (FLE) presenting with the same seizure semiology. The pathogenesis of repeated seizure-induced brain damage is discussed herein.

Methods: Serial changes in regional cerebral volumes were measured in two patients with FLE presenting with intractable clinical courses and cognitive impairments/behavioral problems (FLE(+)) and four FLE patients without cognitive impairments/behavioral problems (FLE(-)). Eleven normal subjects (4-13 years old) served as controls. Volumes of the frontal and prefrontal lobes were determined using a workstation, and the prefrontal-to-frontal lobe volume ratio was calculated.

Results: Frontal and prefrontal lobe volumes revealed growth disturbance in FLE(+) compared with those of FLE(-) and control subjects. In addition, prefrontal-to-frontal lobe volume ratio increased serially in FLE(-) similarly to controls, but was stagnant or decreased in FLE(+). Prefrontal growth also revealed more rapid recovery in a FLE(+) patient with shorter active seizure period.

Conclusion: These findings suggest that repeated seizures may lead to prefrontal growth disturbance. The occurrence of frequent seizures in patients with FLE may be associated with prefrontal lobe growth retardation, which relates to neuropsychological problems and ultimate neuropsychological outcome.