Clinical characteristics of 92 patients with temporal lobe focal cortical dysplasia identified by pathological examination

Comparison of clinical features and surgical outcome in focal cortical dysplasia type 1 and type 2

INTRODUCTION

Recent ILAE classification defined focal cortical dysplasia (FCD) patients with accompanying epileptic lesions as a separate group. We investigated data of patients with sole FCD lesions regarding long-term seizure outcome and different characteristics of FCD type 1 and type 2 patients.

METHODS

Eighty children and adult patients underwent surgery for FCD were included to the analysis of factors differentiating FCD type 1 and type 2 groups and their effect on long-term outcome.

RESULTS

FCD type 2 patients had earlier epilepsy onset (8.1 vs. 6.1 years. p=0.019) and underwent surgery younger than type 1 (18.2 vs. 23.7 years. p=0.034). FCD type 2 patients were more prominently MR positive (77.8% vs. 53.8%. p=0.029), which increased within FCD type 2 group as patients become younger (p=0.028). FCD Type 1 lesions showed mostly multilobar extension and FCD type 2 mostly located in frontal lobe. Seizure freedom was achieved in 65.4% of FCD type 1 patients and 70.4% of FCD type 2 patients. Seven patients had permanent de novo neurological deficits. Mean follow-up time was 5.5 years (Range: 1-11 years).

CONCLUSION

Surgical intervention in carefully selected patients may facilitate favorable seizure outcome leading to better quality of life. FCD type 1 and type 2 groups present with evident differences, which may promote medical and surgical management of these pathologies.

Putting the new ILAE classification of focal cortical dysplasia into practice in western China

PURPOSE

To re-examine drug-resistant epilepsy cases using the revised 2011 ILAE classification of focal cortical dysplasia (FCD).

METHODS

Patients with drug-resistant epilepsy who have undergone epilepsy surgery in West China Hospital between July 2012 and Jun 2014 were included. Clinical histories, pathological diagnoses, and surgical outcomes were reviewed. A questionnaire was developed to investigate the clinical practice of the new classification. A short-term training program on FCD was carried out to improve pathological diagnosis accuracy.

RESULTS

260 consecutive cases (177 male and 83 female) were included. Pathological diagnosis was changed in 70 cases (26.9%) after re-examination. The five most common pathological types were hippocampal sclerosis (19.2%, 50/260), brain tumors (17.7%, 46/260), vascular malformations (16.2%, 42/260), glial scars (11.2%, 29/260) and FCD (10.0%, 26/260). The most common subtype of isolated FCD was FCD IIb (53.8%, 14/26), followed by FCD IIa (42.3%, 11/26) and FCD Ib (3.8%, 1/26). In addition, forty-five cases were diagnosed as associated FCD type III (17.3%, 45/260). Half of patients with FCD achieved Engel class I at two-year follow-up. Questionnaire investigation suggested most participant pathologists lack sufficient knowledge on the new classification. The diagnostic sensitivity for different FCD subtypes was significantly improved by two to six folds after short-term training.

CONCLUSIONS

FCD is an important etiology of drug-resistant epilepsy in western China. It is essential to provide continuing trainings to improve diagnostic precision of FCD in developing countries.

Focal cortical dysplasias in temporal lobe epilepsy surgery: Challenge in defining unusual variants according to the last ILAE classification

OBJECTIVE

Focal cortical dysplasias (FCDs) represent a common architectural cortical disorder underlying pharmacoresistant focal epilepsy. The recent ILAE classification defines different types of FCDs based on their histopathological features, MRI imaging, and presumed pathogenesis; however, their clinical features and their prognostic significance are still incompletely defined. In addition, the combination of different histopathological abnormalities can represent "unusual" subtypes that can be difficult to classify. The aim of our study was to analyze the incidence and the significance of these "unusual" subtypes of FCDs in drug-resistant mesial temporal lobe epilepsy (MTLE).

METHODS

We retrospectively analyzed 133 patients consecutively submitted to tailored anteromesial temporal lobe resection for pharmacoresistant MTLE. Seizure onset, seizure duration, age at surgery, and postoperative seizure outcome were evaluated in relation to the different neuropathological groups defined according to the new ILAE classification.

RESULTS

Focal cortical dysplasias were found in 80 out of 133 patients. Six patients were affected by isolated FCD type I, 12 patients by FCD type II, and 44 patients by FCD type III. Furthermore, we found 18 "atypical" cases (20.5% of all FCD cases and 26.6% of FCDs associated with a principal lesion): 10 cases of associated FCD type II-hippocampal sclerosis (HS) and 8 cases associated with FCD II-epilepsy-associated tumors (EATs).

CONCLUSION

Our results indicate that "unusual" subtypes of FCDs, in particular associated FCD type II, are not uncommon findings, suggesting that they deserve a classification recognition. Similarities in seizure outcome and immunohistochemical and molecular evidences, shared by FCD type II+EATs and EATs, suggest a common pathogenic link. The choice to create a specific unifying class or, on the contrary, to also include "associated FCD type II" in the definition of the new unifying class FCD type III should be further discussed.