Objective: To investigate the clinicopathologic features of focal cortical dysplasia (FCD) in patients with refractory epilepsy.
Methods: The clinical, radiologic and pathologic features of 38 cases of FCD receiving surgical treatment in 2005 were reviewed retrospectively.
Results: The mean age of disease onset was 9.2 years. The disease lasted for 11.9 years on average and often presented as complex partial seizure. Radiologic examination revealed hippocampal sclerosis, or abnormal signals in the grey matter in 21 cases. According to Palmini's classification system, the following pathologic subgroups were identified: FCD type IA (3/38), FCD type IB (20/38), FCD type IIA (5/38) and FCD type IIB (5/38). The remaining 5 cases were classified as mild cortical dysplasia. Topographically, FCD type II was often seen in the extratemporal region (8/10), predominantly in the frontal lobe (5/8). Dual pathology was identified only in cases with FCD type IB. Immunohistochemical study showed that the giant neurons, immature neurons and dysmorphic neurons were strongly positive for NeuN. A small number of balloon cells expressed nestin.
Conclusions: FCD is a common cause of refractory epilepsy. FCD type IB is the predominant pathologic subtype. Associated hippocampal sclerosis is sometimes seen. Clinicopathologic differences between FCD type I and FCD type II are observed.