Refractory epilepsy associated with focal cortical dysplasia:a clinicopathologic analysis of 29 cases

Objective To investigate the clinicopathologic characteristics of refractory epilepsy associated with focal cortical dysplasia (FCD). Methods The clinical,radiologic and pathologic features of 29 cases of FCD receiving surgical treatment from January 2000 to August 2009 were reviewed retrospectively. The follow-up data were analyzed,including drug use,radiological finding and seizure frequency. Results The mean age of disease onset was 23.5 years. The disease lasted for 11.3 years on average and often presented as complex partial seizure. Radiologic examination revealed the hippocampal sclerosis,or abnormal signals in the grey matter in 4 cases. According to Palamini's classification,FCD typeⅠa was found in 6 cases,FCD typeⅠb in 10 cases,FCD typeⅡa in 5 cases,and FCD typeⅡb in 5 cases and the remaining 1 case was classified as mild malformation of cortical development(mild MCD). Topographically,FCD typeⅡ was often seen in the frontal lobe(15 cases),the temporal lobe (8 cases) and the parietal lobe(6 cases). Dual pathology (FCD plus the hippocampal sclerosis) was identified in 4 cases including 2 cases of FCD typeⅠa plus the hippocampal sclerosis,1 case of FCD typeⅠb plus the hippocampal sclerosis and 1 case of FCD typeⅡb plus the hippocampal sclerosis. In addition,5 cases were found to have dysembryoplastic neuroepithelial tumor(DNT). Immunohistochemical study showed that NeuN was strongly positive in the giant neurons,immature neurons and dysmorphic neurons and a small number of balloon cells expressed nestin. MRI revealed no FCD change after surgery. Acording to the Engel and Rasmussen scale for surgical outcome,6 cases were in class Ⅰa,5 in class Ⅰ,3 in class Ⅱand 2 in class Ⅲ and 13 in class Ⅳ. The total cure rate was 55.2% and cure rate in mild subgroup and severe subgroup was 88.9% and 40%,respectively. Conclusions FCD is a common cause of refractory epilepsy. FCD typeⅠb is the predominant pathologic subtype and the histological type of the lesion is related to the prognosis.