Identifying epileptic foci on contrast-enhanced computerized tomographic scans.

There is a statistically significant association between lateralization of interictal epileptic foci and lateralization of numerical changes between enhanced and unenhanced grossly normal computerized tomographic (CT) scans in the area of the suspected focus. This CT change, lateralized to the side of the focus compared to the homologous opposite brain, is a relative increase in CT values after enhancement. This change is seen in both right or left frontal and temporal foci, and is independent of the time of the last seizure, but is not reliably present if there is a gross abnormality on the CT scan. The technique provides additional evidence of lateralization in epileptic patients without clearly lateralized EEG findings.