Abstracts

Multi-drug resistance proteins are expressed in the blood brain barrier (BBB) and blood choroid plexus barrier (BCPB). Resected brain specimens of drug resistant epilepsy patients have been shown to have an over-expression of multi-drug resistance proteins (MDR1/MRP1). It is postulated that the over-expression of these proteins is responsible for the efflux of anti-epileptic drugs from the brain to the blood. There is currently no imaging study showing the efflux mechanism of multi-drug resistance proteins in medically intractable epilepsy. It is the hypothesis of this study that Tc99m Sestamibi, a substrate of MDR1/MRP1, will have a low uptake at the epileptogenic region. Adult surgical candidates for epilepsy surgery were recruited. These candidates has failed at least 3 anti-epileptic medications, has a seizure frequency of of at least once a week, and MRI findings suggestive of mesial temporal sclerosis. Twenty (20) mCi of Tc99m Sestamibi was injected. An interictal brain SPECT imaging was obtained 15 to 60 minutes after injection. Seven (7) patients were recruited. Four had left and 3 had right mesial temporal lobe epilepsy. The age from 23 to 56 years and epilepsy duration ranged 9 to 18 years. In 6 patients, there was low uptake of Tc99m Sestamibi in the choroid plexus adjacent to epileptogenic hippocampus. In one patient, there was a relative low uptake of Sestamibi in the non-epileptogenic region. In drug resistant temporal lobe epilepsy, there is low Tc99m Sestamibi uptake in the choroid plexus adjacent to the epileptogenic hippocampus. This may reflect the modulated MDR1/MRP1 efflux activity at the blood choroid plexus barrier. It is recommended that a larger sample of patients should be studied to validate this observation. (Supported by Bristol-Myers Squib and Cleveland Clinic Foundation.)