DOES TC-99M BICISATE IMAGE LOCAL BRAIN METABOLISM IN LATE ICTAL TEMPORAL-LOBE EPILEPSY

Ictal increase in regional cerebral blood flow as judged by single-pho ton emission tomography (SPET) is a common phenomenon during focal epi leptic seizures. Up to 2 min postictally, regional hyper- perfusion is a consistent finding with technetium-99m hexamethylpropylene amine ox ime (HMPAO) in temporal lobe epilepsy. A new Tc-99m-labelled lipophili c cerebral blood flow imaging agent, bicisate, has considerably longer radiochemical stability and yields better image quality than Tc-99m-H MPAO. In this report, we present the case of a 21-year-old female pati ent with temporal lobe complex partial seizures. Magnetic resonance im aging revealed right hippocampal sclerosis. A dose of 550 MBq of Tc-99 m-bicisate was injected 35 s after the onset of a seizure during intra cranial EEG-videotelemetry. At the moment of injection, subdural EEG d emonstrated the beginning of late ictal discharges and postictal suppr ession in the right temporomesial areas. Late ictal SPET images showed marked right fronto-temporo-parietal hypoactivity. The interictal SPE T study clearly showed right frontotemporal hypoactivity. These prelim inary data suggest that Tc-99m-bicisate shows late ictal/early postict al hypoactivity which might represent the primary change in neuronal m etabolism rather than the secondary change in cerebral blood flow.