ro-16-0154 and Epilepsy--Complex-Partial

Imaging cerebral GABAA receptor density (GRD) with single-photon emission tomography (SPET) and iodine-123 iomazenil is highly accurate in lateralizing epileptogenic foci in patients with complex partial seizures of temporal origin. Limited knowledge exists on how iomazenil SPET compares with magnetic resonance imaging (MRI) in this regard. We present a patient with complex partial seizures in whom MRI had identified an arachnoid cyst anterior to the tip of the left temporal lobe. Contralaterally to this structural abnormality, interictal electroencephalography (EEG) performed after sleep deprivation disclosed an intermittent frontotemporal dysrhythmic focus with slow and sharp waves. On iomazenil SPET images GRD was significantly reduced in the right temporal lobe and thus contralaterally to the MRI abnormality, but ipsilaterally to the pathological EEG findings. These data suggest that iomazenil SPET may significantly contribute to the presurgical evaluation of epileptic patients even when MRI identifies potentially epileptogenic structural lesions.

Topics: Adult; Arachnoid Cysts; Electroencephalography; Epilepsy, Complex Partial; Female; Flumazenil; Humans; Iodine Radioisotopes; Magnetic Resonance Imaging; Receptors, GABA-A; Temporal Lobe; Tomography, Emission-Computed, Single-Photon

Fifteen patients with therapy resistant partial complex seizures with no structural lesions were examined interictally with 123-I-IOMAZENIL SPECT for measurement of benzodiazepine receptor distribution and with 99m-Tc-HMPAO SPECT for measurement of cerebral blood flow distribution. Regional abnormalities were correlated with the seizure onset patterns in EEG later recorded with implanted subdural strips. SPECT scans were made immediately after and at 1 and 2 h after intravenous injection of 123-I-Iomazenil. During that time there was a continuous change from an immediate flow-related distribution toward a more specific receptor distribution. The decay of radioactivity of I-123 in the brain was linear over time. Two patients on benzodiazepine treatment showed much faster elimination and showed no focal abnormalities. Eight patients with clear-cut unifocal seizure onset showed concordant focal benzodiazepine defects. These patients showed a progressive focus/homotopic non-focus enhancement over time much larger than the HMPAO scans in the same patients. Also the estimated focal area of abnormality was more restricted in the Iomazenil scans than in HMPAO scans. Five patients had more complex seizure onset patterns. In these patients a mismatch between the locations of abnormalities in Iomazenil and HMPAO scans were often found but benzodiazepine receptor abnormalities were more circumscribed also in these patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Adolescent; Adult; Anticonvulsants; Cerebral Cortex; Drug Therapy, Combination; Electroencephalography; Epilepsy, Complex Partial; Evoked Potentials; Female; Flumazenil; Follow-Up Studies; Humans; Image Processing, Computer-Assisted; Iodine Radioisotopes; Male; Middle Aged; Receptors, GABA-A; Temporal Lobe; Tomography, Emission-Computed, Single-Photon