INTERICTAL METABOLISM AND BLOOD-FLOW ARE UNCOUPLED TEMPORAL-LOBE CORTEX OF PATIENTS WITH COMPLEX PARTIAL EPILEPSY

We used positron emission tomography (PET) with F-18-2-deoxyglucose (F DG) and O-15 water in 20 patients with complex partial seizures to com pare glucose metabolism and blood flow in temporal lobe epileptic foci identified by ictal scalp-sphenoidal video-EEG telemetry. Glucose met abolism was measured 20 minutes after blood flow without moving the pa tient from the scanner. We also studied 11 patients with Tc-99m-HMPAO single-photon emission computed tomography (SPECT). Both local cerebra l metabolic rate of glucose (LCMRGlc) and regional cerebral blood flow (rCBF) were significantly decreased in temporal cortex ipsilateral to the EEG focus. However, LCMRGlc was reduced by 11.2% in inferior late ral and 11.1% in inferior mesial temporal cortex and rCBF by only 3.2% and 6.1%. The ratio of LCMRGlc to rCBF was significantly reduced in i nferior lateral temporal cortex ipsilateral to the ictal focus (p < 0. 009). Moreover, using standardized criteria, blinded raters found that 16 of 20 patients had focal FDG-PET hypometabolism, all in the epilep togenic region; 10 of 20 had focal 150 water PET hypoperfusion, but it was falsely lateralized in two of these 10; and five of 11 had focal Tc-99m-HMPAO SPECT hypoperfusion, but it was falsely lateralized in tw o of these five. Our data suggest that interictal glucose metabolism a nd blood flow may be uncoupled in epileptogenic cortex.