[Neuropathologic study of massive subcortical heterotopia]

Objective: To investigate the clinicpathologic features and probable mechanisms of massive subcortical heterotopia. Methods: Clinical data, histologic features and neuropathologic data were analyzed in five cases of massive subcortical heterotopia collected from Xuanwu Hospital, Capital Medical University from January 2014 to October 2017. Results: All five patients (three males and two females) had a history of refractory epilepsy with a mean period of 15.4 years (range 7 to 21 years). The median age at surgery was 28.6 years(range 20 to 39 years). Magnetic resonance imaging showed that the lesions were located in the temporal lobe (two cases), parietal lobe (one case), both temporal and occipital lobes (one case) and both temporal and parietal lobes (one case). Pathologic examination disclosed that massive gray matter in subcortical and deep white matter with various shape and size. Moreover, one case also showed subpial and periventricular heterotopias and polymicrogyria. Polymicrogyria or hippocampal sclerosis were seen in the remaining three cases. None of the five patients experienced seizure attacks during the follow-up period. Conclusions: Heterotopia is malformations due to abnormal neuronal migration. Massive subcortical heterotopia due to widespread abnormal neuronal migration is relatively rare. The mechanism of heterotopia together with polymicrogyria needs further discussion.