Type I focal cortical dysplasia: surgical outcome is related to histopathology

Abstract

Pre-surgical and post-surgical data were examined and compared from 215 consecutive patients undergoing surgery for intractable epilepsy. Patients were selected on the basis of a proven histopathological diagnosis of type I focal cortical dysplasia (FCD I), alone or associated with other lesions. The patients were divided into five sub-groups: i) 66 with isolated FCD I, ii) 76 with FCD I and hippocampal sclerosis, iii) 49 with FCD I and tumours, iv) 16 with FCD I and other malformations of cortical development and v) eight with FCD I and anoxic-ischaemic or inflammatory diseases. The duration of epilepsy was greatest in patients with FCD I associated with hippocampal sclerosis, and those with isolated FCD I showed the highest seizure frequency at the time of surgery. Hippocampal sclerosis and tumours were the most frequent pathological lesions associated with FCD I in temporal lobe epilepsy. Febrile seizures significantly correlated with the presence of hippocampal sclerosis and FCD I. Isolated FCD I was observed in 31% of the patients, characterized by frequent seizures, negative magnetic resonance imaging, and frequent frontal or multilobar involvement. In comparison to patients with FCD I associated with hippocampal sclerosis, MCD or tumours, the patients with isolated FCD I had a worse post-surgical outcome (46% in class I). Our findings indicate that there is a high incidence of FCD I associated with other apparently distinct pathologies, particularly those affecting the temporal lobe, and highlight the need for a comprehensive clinicopathological approach for the classification of FCD I.

Clinicopathological associations in temporal lobe epilepsy patients utilising the current ILAE focal cortical dysplasia classification

“…Our finding is in contrast to reports in the recent literature, including patients with HS and FCD, where the outcome was reported to be similar to isolated HS and better than FCD I (Tassi et al, 2009(Tassi et al, , 2010Thom et al, 2009). There were methodological differences in cohort selection between our study and both Tassi et al (2009Tassi et al ( , 2010 and Thom et al (2009), which may explain these disparate findings. Thom et al (2009) excluded all patients with associated FCD, aside from a specific subgroup with temporal lobe sclerosis.…”

“…Previous studies have shown its clinical characteristics reflected its primary pathology (e.g. hippocampal sclerosis (HS) in FCD IIIA) rather than the associated dysplasia (Tassi et al, 2009(Tassi et al, , 2010. We aimed to determine the frequency of FCD type IIIA pathology in a cohort of temporal lobe epilepsy (TLE) surgical patients and whether FCD IIIA has a distinct electroclinical phenotype with identifying imaging features and prognostic implications.…”

“…FCD IIB has well described clinical and imaging features which predict pathology and outcome (Lawson et al, 2005). However, features of FCD I are not well distinguished on clinical presentation, neuroimaging, or histopathology (Chamberlain et al, 2009) and there is variable post-surgical outcome (Fauser et al, 2004;Krsek et al, 2009;Tassi et al, 2010). A revised classification was formulated by an International League Against Epilepsy (ILAE) task force (Blümcke et al, 2011) to address the poor interobserver reliability of the previous classifications and aimed to lessen the clinicopathological discrepancies (Chamberlain et al, 2009).…”

Increased Expression of TRPC5 in Cortical Lesions of the Focal Cortical Dysplasia

“…Patients with FCDs generally present high frequencies of seizures (Tassi et al 2002(Tassi et al , 2010(Tassi et al , 2012. FCDs were first described by Taylor in details, which showed a strange histopathology including abnormal cortical layering and large bizarre neurons such as dysmorphic neurons (DNs) and balloon cells (BCs) (Taylor et al 1971).…”

Coexistent ganglioglioma, focal cortical dysplasia, and hippocampal sclerosis (triple pathology) in chronic epilepsy

“…Whether the changes seen in this setting are acquired, that is, the hippocampal sclerosis lesion and focal cortical dysplasia result from reorganization (dysplasia) or injury resulting in hippocampal sclerosis, or these cases represent a distinct developmental abnormality whereby the hippocampal sclerosis develops secondary to chronic epilepsy resulting from the focal cortical dysplasia lesion is uncertain. The lack of clinical differences and postsurgical outcomes between hippocampal sclerosis and hippocampal sclerosis with focal cortical dysplasia patients would argue for a common etiology [28,29].…”