Significance of FDG-PET Hypermetabolism in Children with Intractable Focal Epilepsy

Abstract

Background: Interictal ¹⁸F-fluorodeoxyglucose-positron emission topography (FDG-PET) hypometabolism is routinely used in the presurgical workup of children with medically intractable epilepsy (MIE). FDG-PET hypermetabolism, however, is rarely seen, and the significance of this finding in the epilepsy workup is not well established. Methods: We performed a retrospective study of patients who underwent FDG-PET during the presurgical workup of MIE over a 4-year period, between 1 January 2010 and 31 December 2013, at the Children’s Hospital Colorado, CO, USA. Results: Focal FDG-PET hypermetabolism was identified in 7 (2.2%) of 317 patients. The median age was 124 months, all cases with catastrophic epilepsy. Surface electroencephalography (EEG) performed concomitantly with FDG injections revealed ictal EEG discharges in 2 patients, frequent interictal epileptiform discharges (IEDs) in 3, occasional IEDs in 1, and no IEDs in 1. All 7 patients underwent functional hemispherectomies. Histopathology revealed type 1 focal cortical dysplasia in all patients. Six (86%) were completely seizure-free (Engel class I) and 1 had extremely infrequent seizures (Engel class II) (mean follow-up, 47.4 months). Conclusion: While a rare finding, interictal PET hypermetabolism does occur, may help identify epileptogenic zones, and assessment to reveal it should be made by concomitant use of surface EEG during PET scans.

Epileptic Spasms in a Large Hypothalamic Hamartoma Cohort

“…Interictal FDG-PET hypometabolism is a feature of the epileptogenic cortex surrounding the anatomical lesions. 18 Schur et al 19 described the importance of interictal FDG-PET hypermetabolism as an increased intrinsic metabolic requirement of the epileptogenic cortex of focal cortical dysplasia.…”

Cerebellar Contribution to Absence Epilepsy

“…It is challenging to apply positron emission tomography (PET) to investigate ictal phenomena and their interpretation [63]. That is why the case of absence status epilepticus is of particular interest in clarifying its pathogenesis with [18F]FDG-PET method [64].…”

Hypermetabolism on Pediatric PET Scans of Brain Glucose Metabolism: What Does It Signify?

“…Patients (particularly children) with frequent seizures may occasionally experience a seizure during the approximately 30 minute 18F-FDG uptake period, thus yielding an ictal PET scan. In some institutions, patients with frequent seizures are monitored with an electroencephalogram during the tracer uptake period and, if a clinical or subclinical seizure occurs, its localization, timing and duration can be accurately analyzed (2). If the seizure occurs early enough (approximately first 10 minutes) during the tracer uptake period and lasts for more than a few minutes, hypermetabolism may be seen on the images and may provide useful localization data (Figure 1A), both from the PET scan itself and from the concurrent electroencephalogram if performed.…”