Thalamic and cerebellar hypermetabolism and cortical hypometabolism during absence status epilepticus

Abstract

We report on a 17-year-old girl with absence status epilepticus who developed recurrent motionless confusional state and continuous generalised 3-4 Hz rhythmic delta waves on electroencephalogram (EEG). The patient had no history of absence, myoclonus or generalised convulsion. Her seizure was resistant to a combination of antiepileptic drugs including carbamazepine. Ictal positron emission tomography using [¹⁸F]fluorodeoxyglucose ([¹⁸F]FDG-PET) revealed hypermetabolism of the bilateral thalamus and cerebellum and hypometabolism of the frontal, parietal and posterior cingulate cortices. We diagnosed her seizure as absence status and obtained remission by changing medication. The findings of ictal metabolic alteration in previous studies and in our case confirm the pathogenic importance of the thalamus in absence status and that associated cortical deactivation and cerebellar activation may be related to the generation or maintenance of epileptic EEG discharges.

Keywords: clinical neurophysiology; epilepsy and seizures; neuroimaging.

Figure 1

Electroencephalogram recorded during the epileptic state. Generalised rhythmic delta waves continued.

Figure 2

Changes in glucose uptake levels measured by [18F]FDG-PET as compared with those of the controls, using statistical parametric mapping (SPM12: Wellcome Trust Centre for Neuroimaging, University College London, London, UK). Relative hypermetabolism (yellow) and hypometabolism (red) are shown in (A) and (B), respectively (p<0.001), superimposed on Montreal Neurological Institute space T1-weighted MR axial images.=O4467