Magnetic resonance imaging in refractory focal epilepsy with normal CT scans.

One hundred patients suffering from focal epilepsy with complex partial seizures refractory to medical treatment and showing no abnormality at CT were explored by MRI with an 0.5 Tesla magnet. MRI detected an abnormality in 25 patients with, in 17 of them, good correlation between MRI and clinical as well as electroencephalographic findings. Abnormal morphology and signal was found in 5 patients, with positive CT results on reexamination of previous CT images or on new CT scans in 4 of them. There was a diffuse temporal lobe high-intensity signal in 3 cases and a localized high-intensity signal in 9 cases (temporal lobe 4, occipital lobe 3, frontal lobe 1, fronto-parietal and parietal lobes 1). Thus, in 13% of the cases MRI demonstrated a lesion that had not been detected at CT, and the location of the lesion was concordant with clinical and electroencephalographic data.