Abstracts

RATIONALE: Some patients with refractory epilepsy have normal MRI scans but cortical dysplasia can be identified within their surgical specimens. This study reports our findings with such patients. METHODS: Four patients with refractory epilepsy were studied. Patient I: 35 year-old, complex partial seizures (CPS)since the age of 2. Interictal and ictal EEG with right temporal lobe abnormalities. MRI was normal. He was submitted to a right cortico-amygdalo-hippocampectomy (CAH). Patient II: 32 year-old, CPS since the age of 8. Interictal EEG showed bilateral independent temporal lobe spiking. MRI showed bilateral mesial temporal sclerosis (MTS), with a smaller hippocampus at the right side. She was submitted to a right CAH. Patient III: 21 year-old, right visual SPS since the age of 5. Interictal and ictal EEG showing left temporo-occipital abnormalities. MRI was normal. He was submitted to subdural electrodes'implantation and subsequently to a left posterior quadrantectomy. Patient IV: 16 year-old, hypermotor seizures since the age of 2. Interictal EEG showed generalized secondary bilateral synchrony and ictal EEG was non-localizatory. MRI was normal. She was submitted subdural electrodes implantation and subsequently underwent a right frontal resection. RESULTS: Patients I, II, and III has been seizure free since surgery. Patient IV is in Engel's class II. Macroscopic evaluation of the surgical specimen was normal in Patients I and II. Dysplasic cells were found on microscopic analysis, without disruption of the gyral anatomy. Patient III had a 2 cm macroscopic temporo-occipital area of cortical dysplasia. Patient IV had a 8 mm mesial presupplementary area macroscopic area of cortical dysplasia. CONCLUSIONS: Despite the use of high-resolution MRI scanners some areas of cortical dysplasia remain undetected preoperatively. Further refinement of the MR technique may made it possible to recognized some of these patients, especially those in whom lesions cause disruption of the gyral anatomy and could be seen macroscopically, such as in patients III and IV. On the other hand, patients with microscopic cortical dysplasia such as patients I and II might remain undiagnosed with current MR technology.