The investigators propose a prospective study of 20 control subjects and 180 consecutive patients with possible non-convulsive status epilepticus (NCSE). The investigators will obtain three functional images of the brain:
1. Fluorodeoxyglucose positron emission tomography (FDG-PET) 2. Perfusion (and structural) magnetic resonance (MR) images 3. Computed tomography (CT) perfusion.
Brain hypermetabolism/hyperperfusion is a strong argument to confirm a diagnosis of non-convulsive status epilepticus.
The aim is to determine which of the three functional imaging techniques is the most sensitive and easy to obtain in the detection of hypermetabolism/hyperperfusion. The investigators will determine which EEG patterns are associated with hypermetabolism/perfusion.
The investigators will further study and describe the management with antiseizure medication and outcome of the group with possible non-convulsive status epilepticus WITH hypermetabolism/hyperperfusion versus the group with possible non-convulsive status epilpticus WITHOUT hypermetabolism/hyperperfusion.
The investigators will make recommendations for an imaging protocol in possible NCSE for widespread use. The aim is to offer guidelines to incorporate imaging in the diagnosis, management and prognosis of NCSE in patients with the ictal-interictal continuum.
None
The patient has a contra-indication for MRI such as metal implants
The patient has contrast sensitivity
The patiensuffers from claustrophobia or cannot tolerate confinement during PET-MRI scanning procedures
Parallel
MRI scan including arterial spin labelling of the brain
Diagnostic testArterial Spin Labelling sequence, T2-weighted FLAIR images and T1-weighted images and diffusion weighted imaging sequence will be recorded
CT perfusion scan of the brain
Diagnostic testSiemens Naeotom Alpha with quantum technology (photon-counting)
FDG-PET scan of the brain
Diagnostic testAn FDG-PET scan will be acquired on a GE Signa 3T PET-MR scanner. FDG-PET images will be assessed for focal hypermetabolism, including semiquantitative analysis of the maximal standard uptake value (SUVmax) relative to the SUVmax of the pons (SUVr pons)
Sensitivity of MRI arterial spin labelling, CT perfusion and FDG-PET of the brain to detect hyperperfusion/hypermetabolism in possible non-convulsive status epilepticus
The investigators will determine which diagnostic test (MRI, CT or FDG-PET) is most sensitive in detecting hyperperfusion/hypermetabolism in possible non-convulsive status epilepticus to confirm a diagnosis of non-convulsive status epilepticus
Correlation between FREQUENCY of ictal-interictal EEG patterns within 30 minutes after FDG-PET injection and standardised uptake value on FDG-PET.
The investigators will assess the correlation between standardised uptake value of the cerebral hypermetabolic region and the frequency of ictal-interictal EEG patterns within 30 minutes after injection of FDG. The frequency of ictal-interictal EEG patterns will be scored semi-quantitatively based on the American Clinical Neurophysiology Criteria (ACNS) criteria (2021).
Correlation between PREVALENCE of ictal-interictal EEG patterns on EEG within 30 minutes after FDG-PET injection and standardised uptake value on FDG-PET.
The investigators will assess the correlation between standardised uptake value of the cerebral hypermetabolic region and the prevalence of ictal-interictal EEG patterns within 30 minutes after injection of FDG. The prevalence of ictal-interictal EEG patterns will be scored semi-quantitatively based on the American Clinical Neurophysiology Criteria (ACNS) (2021)
The seizure freedom of patients with hypermetabolism compared to those with hypometabolism within 24 hours after undergoing an FDG-PET scan.
The investigators will assess the seizure freedom of patients in the hypermetabolic vs hypometabolic group. Patients will receive video EEG-monitoring for 24 hours after FDG-PET. Seizures will be defined according to current American Clinical Neurophysiology Criteria (ACNS) (2021) based on electrographic and clinical data. Hypermetabolism/hypometabolism will be qualitatively scored by a trained nuclearist.
Correlation between SHARPNESS of ictal-interictal EEG patterns on EEG within 30 minutes after FDG-PET injection and standardised uptake value on FDG-PET.
The investigators will assess the correlation between standardised uptake value of the cerebral hypermetabolic region and the sharpness of ictal-interictal EEG patterns within 30 minutes after injection of FDG. The sharpness of ictal-interictal EEG patterns will be scored semi-quantitatively based on the American Clinical Neurophysiology Criteria (ACNS) (2021)
Correlation between AMPLITUDE of ictal-interictal EEG patterns within 30 minutes after FDG-PET injection and standardised uptake value on FDG-PET
The investigators will assess the correlation between standardised uptake value of the cerebral hypermetabolic region and the amplitude of ictal-interictal EEG patterns within 30 minutes after injection of FDG. The amplitude of ictal-interictal EEG patterns will be scored semi-quantitatively based on the American Clinical Neurophysiology Criteria (ACNS) (2021)
Correlation between EVOLUTION of ictal-interictal EEG patterns on EEG within 30 minutes after FDG-PET injection and standardised uptake value on FDG-PET.
The investigators will assess the correlation between standardised uptake value of the cerebral hypermetabolic region and evolution of ictal-interictal EEG patterns within 30 minutes after injection of FDG (i.e. static, fluctuating or evolving). The presence of fluctuation and evolution of ictal-interictal EEG patterns will be scored based on the American Clinical Neurophysiology Criteria (ACNS) (2021)
Functional imaging in possible non-convulsive status epilepticus and INTERICTAL BURDEN
The investigators will compare interictal burden, defined as a percentage of ictal-interictal EEG patterns during continuous EEG monitoring, in the group with possible non-convulsive status epilepticus WITH hypermetabolism/hyperperfusion versus the group with possible non-convulsive status epilepticus WITHOUT hypermetabolism/hyperperfusion
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