LACK OF EFFECT OF CONCOMITANT CLOBAZAM ON INTERICTAL I-123 IOMAZENIL SPECT

Single photon emission computed tomography (SPECT) is being increasing ly used as an adjunctive technique in the localisation of epileptogeni c foci prior to surgery. Fourteen patients (five male, nine female; me an age 31 years) with refractory complex partial seizures, all of whom had abnormal Tc-99 HM-PAO SPECT scans, were imaged again using the be nzodiazepine receptor ligand I-123-iomazenil. Eleven of these patients displayed the same abnormality on both scans. The magnitude of the de ficit, however, was slightly greater (P < 0.05) on the iomazenil scan compared with the HM-PAO study. These 11 patients were then randomised into two groups. Group 1 (n = 7) received clobazam 20 mg/day for a mi nimum of 7 days before a second iomazenil study was performed. Patient s in group 2 (n = 4) underwent a second iomazenil scan at the same tim e interval as those in group 1, but without the additional clobazam. T he resultant scans were reported blind to treatment. There were no qua litative or quantitative differences between the first and second ioma zenil studies in either group. Patients can be imaged using I-123-ioma zenil without withdrawing clobazam therapy. From this preliminary stud y, there seems little advantage in using iomazenil in place of HM-PAO to delineate the extent of the zone of epileptogenesis. Whether iomaze nil SPECT will prove to be more sensitive in identifying the site of t he epileptic focus remains to be determined.