Effect of generalized spike‐and‐wave discharge on glucose metabolism measured by positron emission tomography

Abstract

Positron emission tomography was used to study the cerebral metabolic rate for glucose (CMRGlc) in 7 adult patients with generalized spike-and-wave activity in the electroencephalogram. No consistent changes were seen in the CMRGlc. There was a slight trend toward an increased CMRGlc in 2 patients with primary generalized epilepsy, while in the 5 other patients with minor deviations from this condition or with secondary generalized epilepsy, the CMRGlc was unaffected by spike-and-wave activity or was below the normal range. Neither the amount of spike-and-wave activity in the EEG nor the presence of clinically evident absence seizures appeared to influence the CMRGlc. Therefore, we conclude that neuronal activity underlying spike-and-wave discharge does not seem to require increased glucose utilization.

Insights into the Mechanisms of Absence Seizure Generation Provided by EEG with Functional MRI

“…The use of positron emission tomography (PET) with fluorinated glucose (FDG) provides information about changes in metabolic activity but over a much longer time scale. In children with AS, there was a diffuse increase in cerebral glucose metabolism compared to baseline during seizures (37); however, the same finding has not been observed in adults with IGE during GSW (38, 39). The use of H 2 15 O with PET provides a functional marker for blood flow rather than glucose metabolism and has demonstrated that during AS, there is a global increase in CBF, seen greatest in the thalamus (41).…”

“…Although EEG with functional MRI (EEG-fMRI) has become a dominant means of studying the functional consequences of AS on the human brain, a number of other techniques have also been used to study blood flow (34–36) and metabolic changes (37–39) associated with AS. Doppler ultrasonography of the middle cerebral artery (MCA) has demonstrated a reduction in blood flow as a result of AS (34, 40), whereas single photon emission tomography (SPECT) identified decreases in cerebral blood flow (CBF) in the frontal and parieto-occipital areas during the ictal phase and generalized blood flow increases during the postictal phase without an increase metabolic demand (35).…”

Thalamic and cerebellar hypermetabolism and cortical hypometabolism during absence status epilepticus

“…Theodore et al 10 investigated two patients using [18F]FDG-PET during ictal and interictal periods and found decrease of metabolism in frontal, temporal and thalamic cortices in one patient and increase of metabolism in the caudate nucleus and the frontal cortex in another. Ochs et al 11 investigated two patients using [18F]FDG-PET and found metabolic increase of the overall brain in one and no change in the other. These inconsistent results in the initial studies may have been derived from differences in the patient's conditions at the time of the scan and limited resolution of PET.…”

Positron Emission Tomography Studies of Cerebral Blood Flow and Glucose Metabolism

“…Absence status, however, was associated with a reduction in cerebral glucose metabolism. There were no focal abnormalities and the rate of metabolism did not correlate with the amount of spike-wave activity (72)(73)(74). I8FDG PET studies have poor temporal resolution, 70-80% of cerebral uptake occurring during a 15-min period following intravenous injection, with the consequence that in a patient with frequent absences, there is an amalgam of preictal, ictal and postictal periods contributing to one scan.…”