Transient focal cortical increase of interictal glucose metabolism in Sturge-Weber syndrome: Implications for epileptogenesis

Abstract

SUMMARYPurpose: To investigate clinical correlates and longitudinal course of interictal focal cortical glucose hypermetabolism in children with Sturge-Weber syndrome (SWS). Methods: Fluorodeoxyglucose positron emission tomography (FDG-PET) scans of 60 children (age range 3 months to 15.2 years) with Sturge-Weber syndrome and epilepsy were assessed prospectively and serially for focal hypo-or hypermetabolism. Thirty-two patients had two or more consecutive PET scans. Age, seizure variables, and the occurrence of epilepsy surgery were compared between patients with and without focal hypermetabolism. The severity of focal hypermetabolism was also assessed and correlated with seizure variables. Key Findings: Interictal cortical glucose hypermetabolism, ipsilateral to the angioma, was seen in nine patients, with the most common location in the frontal lobe. Age was lower in patients with hypermetabolism than in those without (p = 0.022). In addition, time difference between the onset of first seizure and the first PET scan was much shorter in children with increased glucose metabolism than in those without (mean: 1.0 vs. 3.6 years; p = 0.019). Increased metabolism was transient and switched to hypometabolism in all five children where follow-up scans were available. Focal glucose hypermetabolism occurred in 28% of children younger than the age of 2 years. Children with transient hypermetabolism had a higher rate of subsequent epilepsy surgery as compared to those without hypermetabolism (p = 0.039). Significance: Interictal glucose hypermetabolism in young children with SWS is most often seen within a short time before or after the onset of first clinical seizures, that is, the presumed period of epileptogenesis. Increased glucose metabolism detected by PET predicts future demise of the affected cortex based on a progressive loss of metabolism and may be an imaging marker of the most malignant cases of intractable epilepsy requiring surgery in SWS.

Glucose Metabolic Profile by Visual Assessment Combined with Statistical Parametric Mapping Analysis in Pediatric Patients with Epilepsy

“…Interestingly, hypermetabolism could be detected in the acute phase of epileptic syndrome, with continuous spikes and waves during slow sleep, but disappeared in the recovery phase (28). Transient hypermetabolism was observed in 9 of 60 patients with SturgeWeber syndrome, which was considered to reflect a period of epileptogenesis (29). In an autoradiography study, 14 C-FDG uptake was related to the general intensity of synaptic activity rather than the nature of excitation or inhibition (30).…”

Neuroimaging the Epileptogenic Process

“…These changes were then followed by progressive loss of metabolism as epilepsy established itself [104].…”

The Role of Radionuclide Imaging in Epilepsy, Part 2: Epilepsy Syndromes

“…It has been hypothesized that interictal hypermetabolism in young children with SWS may reflect a transient increase of metabolic demand in cortex undergoing excitotoxic tissue damage. Affected children often (but not always) develop intractable seizures requiring surgical resection (62), and it appears that the presence of early cortical hypermetabolism on PET may be an imaging marker of subsequent severe epilepsy, requiring early surgical intervention (62). In some young patients, serial 18 F-FDG PET scans show rapidly progressing and severe hypometabolism in the affected area, probably because of rapid demise of the brain tissue associated with the angioma; these patients will have improvement in seizure status and paradoxic preservation of cognitive function and therefore may not require surgical intervention (Fig.…”