Abstracts

Rationale: Focal cortical dysplasia (FCD) is one of the common causes of pharmacoresistant focal epilepsy which may be amenable by surgery. They may be demonstrated by MRI or can be confirmed only after surgery by the investigation of resected brain tissue. However, there is not enough data related to FDG-PET findings in FCDs. These are the preliminary results of an ongoing study which investigates the FDG-PET findings in FCD compared to MRI and histolopathologic subgroups.Methods: Eighty-eight patients who had surgery for intractable epilepsy proved to have FCD according to the patologic investigation of the resected tissue. Twelve patients who had performed FDG-PET during the presurgical evaluation were analyzed seperately considering the histopathologic classification (Palmini et al, 2004) and FDG-PET findings . Intracranial recordings were performed in 10 out of 12 patients to define the epileptogenic zone.Results: Six patients had temporal , 6 had frontal lobe localization of FCD. Histopathology was type IIA in 6, type IA in 4, type IB and type IIB in 1 each patient. Three patients (25%) had no abnormality on FDG-PET where MRI showed the lesion in 2 of them (2 type IIA, 1 type IB). FDG-PET and MRI were both normal in 1 patient with frontal localisation (type IIA). FDG-PET hypometabolism was demonstrated in 2 patients with type IIA who had normal MRI (1 temporal, 1 frontal) and histologial classification of all patients without MRI pathology was type IIA.Conclusions: FDG-PET may be useful in localisation of the cortical abnormality in patients with FCD even when MRI doesn’t reveal the lesion. Although the number of patients is not adequate yet for definitive assumption, patients with FCD type IIA may demonstrate FDG-PET hypometabolism even though their MRI is normal. Reference Palmini A., Najm I., Avanzini G. et al. Terminology and classification of the cortical dysplasias. Neurology.2004,(Suppl 3):S2-8.