Abstract
ObjectiveThe aim of this study was to investigate variant patterns of cortical venous oxygenation during status epilepticus (SE) using susceptibility-weighted imaging (SWI).MethodsWe analyzed magnetic resonance imaging (MRI) scans of 26 patients with clinically witnessed prolonged seizures and/or EEG-confirmed SE. All MRI exams encompassed SWI, dynamic susceptibility contrast perfusion MRI (MRI-DSC) and diffusion-weighted imaging (DWI). We aimed to identify distinct patterns of SWI signal alterations that revealed regional or global increases of cerebral blood flow (CBF) and DWI restrictions. We hypothesized that SWI-related oxygenation patterns reflect ictal or postictal patterns that resemble SE or sequelae of seizures.ResultsSixteen patients were examined during nonconvulsive status epilepticus (NCSE) as confirmed by EEG, a further ten patients suffered from witnessed and prolonged seizure episode ahead of imaging without initial EEG. MRI patterns of 15 of the 26 patients revealed generalized hyperoxygenation by SWI in keeping with either global or multifocal cortical hyperperfusion. Eight patients revealed a focal hyperoxygenation pattern related to focal CBF increase and three patients showed a focal deoxygenation pattern related to focal CBF decrease.ConclusionsSWI-related hyper- and deoxygenation patterns resemble ictal and postictal CBF changes within a range from globally increased to focally decreased perfusion. In all 26 patients the SWI patterns were in keeping with ictal hyperperfusion (hyperoxygenation patterns) or postictal hypoperfusion (deoxygenation patterns) respectively. A new finding of this study is that cortical venous patterns in SWI can be not only focally, but globally attenuated. SWI may thus be considered as an alternative contrast-free MR sequence to identify perfusion changes related to ictal or postictal conditions.
Highlights
Sixteen patients were examined during nonconvulsive status epilepticus (NCSE) as confirmed by EEG, a further ten patients suffered from witnessed and prolonged seizure episode ahead of imaging without initial EEG
Eight patients revealed a focal hyperoxygenation pattern related to focal cerebral blood flow (CBF) increase and three patients showed a focal deoxygenation pattern related to focal CBF decrease
In all 26 patients the susceptibility-weighted imaging (SWI) patterns were in keeping with ictal hyperperfusion or postictal hypoperfusion respectively
Summary
We analyzed magnetic resonance imaging (MRI) scans of 26 patients with clinically witnessed prolonged seizures and/or EEG-confirmed SE. All MRI exams encompassed SWI, dynamic susceptibility contrast perfusion MRI (MRI-DSC) and diffusion-weighted imaging (DWI). The study was approved by the local ethics committee (cantonal ethics committee Bern, Switzerland). Because of the retrospective study design the informed consent was waived. Patients underwent MRI immediately after a neurological examination to identify acute neurological symptoms related to the seizure and their respective pathology. Inclusion criteria were: (1) a clinically witnessed general convulsive seizure with a prolonged seizure episode (PSE) in accordance with an operational definition of >5 minutes of continuous seizure activity or intermittent seizure activity, or (2) EEG-confirmed persisting NCSE, (3) an MRI with DWI, SWI and dynamic susceptibility contrast (DSC) MRI at emergency admission. Patients were excluded if image quality was poor, e.g. due to motion artifacts
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