Evidence for nodular epileptogenicity and gender differences in periventricular nodular heterotopia

Objective: To determine whether clinical differences between the sexes seen in periventricular nodular heterotopia (PNH) have structural correlates on imaging. Background: PNH is the most common dysgenesis associated with hip pocampal sclerosis (HS). Women with PNH have normal intellect; men may have mental retardation and other changes. Familial PNH, seen in women, is Link ed to Xq28-a region also abnormal in a sporadic male infant with PNH and re tardation-suggesting sexual differences in gene expression. Epilepsy associ ated with PNH may be refractory to drugs, and surgery for associated HS doe s not stop seizures, suggesting intrinsic epileptogenicity of PNH. Methods: Quantitative MRI analysis was performed using established techniques for d etecting subtle structural changes in 13 female patients (11 sporadic and t wo familial) and four male patients (sporadic). Results: There is structura l heterogeneity in PNH, even in patients with bilateral PNH. On MRI, men ha ve more cerebral abnormalities beyond PNH than control subjects or female p atients (p < 0.005). Conclusions: The findings support the concept of intri nsic epileptogenicity of PNH. There may be additional structural abnormalit ies relevant to seizure generation, especially in men. Structural heterogen eity, and widespread abnormalities, may need consideration when patients ar e referred for surgical treatment or when additional studies of patients wi th PNH are conducted.