technetium-tc-99m-bicisate and Epilepsy--Absence

Radiopharmaceutical brain imaging is clinically applied in planning resective epilepsy surgery. Cerebral sites of seizure generation-propagation are highly associated with regions of hyperperfusion during seizures, and with glucose hypometabolism interictally. For surgical planning in epilepsy, the functional imaging modalities currently established are ictal single photon emission computed tomography (SPECT) with [(99m)Tc]technetium-hexamethylpropyleneamine oxime (HMPAO) or with [(99m)Tc]technetium-ethylene cysteine dimer (ECD), and interictal positron emission tomography (PET) with 2-[(18)F]fluoro-2-deoxyglucose (FDG). Ictal SPECT and interictal FDG PET can be used in presurgical epilepsy evaluations to reliably: (1) determine the side of anterior temporal lobectomy, and in children the area of multilobar resection, without intracranial electroencephalographic recording of seizures; (2) select high-probability sites of intracranial electrode placement for recording ictal onsets; and, (3) determine the prognosis for complete seizure control following anterior temporal lobe resection. Coregistration of a patient's structural (magnetic resonance) and functional images, and statistical comparison of a patient's data with a normal data set, can increase the sensitivity and specificity of these SPECT and PET applications to the presurgical evaluation.

Topics: Brain; Cysteine; Epilepsy; Epilepsy, Absence; Epilepsy, Generalized; Epilepsy, Temporal Lobe; Fluorodeoxyglucose F18; Humans; Organotechnetium Compounds; Predictive Value of Tests; Preoperative Care; Radiopharmaceuticals; Technetium Tc 99m Exametazime; Tomography, Emission-Computed; Tomography, Emission-Computed, Single-Photon

Single photon emission computed tomography (SPECT) is currently used in the presurgical evaluation of medically intractable partial epilepsies, but not very often, in generalized epilepsy. In the present study, we used the SISCOM procedure, which represents the fusion of MRI and ictal-interictal difference SPECT images using (99m)Tc-ECD, to study cerebral blood flow changes during the ictal and postictal phases of typical childhood absence seizures. The study was performed on four children with typical, difficult to treat absence seizures, aged 10-13 years at the time of scan. The delay between the onset of absence seizures and the injection of (99m)Tc-ECD was carefully noted. One scan was performed during the ictal phase and showed diffuse blood flow decreases, while the three other scans performed during the postictal phase, showed generalized blood flow increase. These data are consistent with most previous data reporting generalized changes in functional activity, not limited to the thalamo-cortical circuit in which absence seizures originate, and a decrease in cerebral blood flow during the ictal phase. Our data are concordant with the hypothesis that neuronal activity underlying the occurrence of spike-and-wave discharges does not seem to require an increase in metabolic demand and blood flow rates. [Published with videosequences].

Topics: Adolescent; Anticonvulsants; Blood Flow Velocity; Brain; Cerebral Cortex; Child; Cysteine; Dominance, Cerebral; Drug Therapy, Combination; Electroencephalography; Energy Metabolism; Epilepsy, Absence; Evoked Potentials; Female; Humans; Image Processing, Computer-Assisted; Magnetic Resonance Angiography; Male; Neural Pathways; Organotechnetium Compounds; Radiopharmaceuticals; Regional Blood Flow; Sensitivity and Specificity; Thalamus; Tomography, Emission-Computed, Single-Photon