Hemodynamic patterns of status epilepticus detected by susceptibility weighted imaging (SWI)

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1 Hemodynamic patterns of status epilepticus detected by susceptibility weighted imaging (SWI) Poster No.: C-1086 Congress: ECR 014 Type: Scientific Exhibit Authors: J. AELLEN, E. Abela, R. Kottke, E. Springer, M. El-Koussy, G Schroth, R. Wiest, J. Gralla, R. K. Verma ; Mezieres FR/CH, 3 Bern/CH, Berne/CH Keywords: Neuroradiology brain, MR-Diffusion/Perfusion, MR, Imaging sequences, Seizure disorders DOI: /ecr014/C-1086 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. Page 1 of 11

2 Aims and objectives Aim of this retrospective study was to investigate pathological radiological findings in the SWI sequence of patients experiencing convulsive (SE) or non-convulsive status epilepticus (NCSE) in the acute setting, and to evaluate their possible clinical use as a diagnostic tool. Recently, magnetic resonance imaging and computed tomography have emerged as promising tools to help in diagnosing SE in the acute setting. In a few studies a focal 1-5 hyperperfusion of the affected cerebral region was demonstrated. Further, the affected regions showed partly a diffusion restriction in some studies, presumably because compensatory mechanism of hyperperfusion is insufficient to prevent the stimulation of 6-8 anaerobic glycolysis due to ictal activity leading to ADC reductions. The role of SWI has not yet been evaluated in the acute ictal setting with respect to alterations in cortical vein appearance due to perfusion changes. It is assumed, that the deoxy-hemoglobin content in veins correlates with their prominence and darkness in SWI due to their paramagnetic 9 properties. Since focal parenchymal areas are expected to be hyperperfused during seizure activity, the oxy-hemoglobin content is higher and a correlating pseudo-narrowing of cortical veins would be expected due to a lower deoxy-hemoglobin content, and therefore decreased paramagnetic properties. We investigated the appearance of focal pseudo-diminishing of cortical veins in SE and further evaluated a presumed correlation between the location of pseudo-narrowed cortical veins in SWI with findings in DWI, DSCE, EEG and clinical symptoms. Methods and materials Inclusion criteria for patients for this retrospective study were a clinically and/or electrophysiologically confirmed convulsive or non-convulsive status epilepticus, MRI in the acute setting with DSCE, DWI and SWI sequences with a focal decreased mean transit time (MTT) in DSCE. A total of 13 patients (9 female and 4 male; age range 1 to 87y ; mean 37.1y) fulfilled these criteria. 11 of 13 subjects had received EEG prior or after MRI (time range 4 h 15 min before and 6 weeks after MRI acquisition). In 5 patients SE was confirmed with EEG, in 1 patient by EEG and seizure event and 7 with seizure event followed by symptoms like e.g. apathy or coma. Clinical and demographic characteristics are summarized in Tab.1. Data acquisition : Imaging studies were performed using a 1.5T and a 3T Siemens scanner (Magnetom Avanto, Magnetom Trio, respectively; Siemens Medical Solution, Erlangen, Germany) with a 1-channel head coil. Page of 11

3 The MRI protocol performed was our local emergency / stroke protocol, which includes the following sequences: axial DWI, axial T SE, ToF angiography, perfusion imaging, contrast-enhanced angiography of the cervical and intracranial arteries, and an axial T1 SE post-contrast. The SWI and minimum intensity projections (mip) images were generated automatically after acquisition by the scanner software. For both scanners tracer concentration-time curves of the perfusion sequence were analyzed using Siemens Workstations to obtain parametric colour-coded maps of Mean Transit Time (MTT), Time-To-Peak (TTP), relative Cerebral Blood Flow (rcbf) and relative Cerebral Blood Volume (rcbv). Data analysis: To evaluate MRI sequences, two neuroradiologists were blinded to patient history, except for the information of a current clinically and/or electroclinically confirmed SE and a focal parenchymal area with decreased MTT, without knowledge of the exact location. First SWI was analyzed. If cortical veins were undetectable or less visible in a parenchymal area compared to the cortical veins of the opposite hemisphere the area was noted as positive. DSCE: After visual evaluation, areas of shortened MTT and increased rcbf were noted. At last DWI images were analyzed. If cortical diffusion restriction occurred, the region was noted. EEG results of the 11 patients with EEG were analyzed, and if epileptiform signals (epileptiform discharges (ED), periodic lateralized epileptiform discharges (PLED) or signs compatible with postictal changes (focal or general slowing) occurred, the region with these alterations was noted. Finally all observed pathological findings of the MRI sequences and the EEG were compared to each other and correlated with the clinical findings (for details see Tab. 1 in result section). Results All 13 patients showed a focal parenchymal area with pseudo-narrowed cortical veins on SWI, correlating with focal hyperperfused areas (CBF increase and MTT shortening in all patients) Fig. 1 on page 4, Fig. on page 6, and cortical DWI restriction in 6/13 patients (46.%) Fig. 3 on page 8. Six patients had EEG confirmed NCSE (3 with epileptiform discharges - ED, and 3 with periodic lateralized epileptiform discharges - PLED). The localization of all areas with epileptiform signals correlated with the focal disturbed areas in SWI and DSCE. Postictal findings in EEG with focal wave slowing were found in another 3 patients. These changes again correlated with the localizations of pseudo-narrowed cortical veins and hyperperfusion in SWI and DSCE images, respectively. Besides a seizure in convulsive SE the most frequent neurological symptoms were hemiparesis found in 6 patients and/or aphasia found in 3 patients. Again, areas of pathological SWI and DSCE findings correlated with those parenchymal areas Page 3 of 11

4 responsible for these two symptoms (for detailed information see Tab.1 = Fig. 4 on page 9 ). Images for this section: Page 4 of 11

5 Fig. 1: years old female with MELAS syndrome and acute global aphasia. a) In SWI cortical veins are diminished on temporal left. b) In correlation subtle diffusion restriction Page 5 of 11

6 and a focal hyperperfusion with MTT shortening (c) and increased rcbf (d); (see Tab.1 Pt.No.3). Page 6 of 11

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8 Fig. : 4 years old girl with fever seizure and clinically status epilepticus. a) Pseudonarrowed or pseudo-diminished cortical veins are found temporal-parietal and occipital left without correlating diffusion restriction (b, but hyperperfusion in MTT (shortened) and rcbf (increased), see c and d; (see Tab.1 patient No. 5). Page 8 of 11

9 Fig. 3: 4 years old girl with fever seizure and left hemisyndrom. a) Pseudo-narrowed or pseudo-diminished cortical veins are found frontal right with b) correlating diffusion restriction and c) hyperperfusion in the MTT (shortened) and d) CBF maps (increased) (see Tab.1, Patient No.4). Fig. 4: Tab.1: Detailed information of patients; (EEG legend: GS = general slowing, FS = focal slowing, PLED = periodic lateralized epileptiform discharges, ED = epileptiform discharges, SZ = seizures) Page 9 of 11

10 Conclusion In summary this study demonstrates a correlation of pseudo-narrowed or pseudodiminished cortical veins in SWI with ictal and postictal signals in EEG, clinical findings, DSCE and DWI images with focal hyperperfusion and partly diffusion restriction in patients presenting with SE or NCSE. The SWI findings can be explained by a decreased amount of deoxygenated blood and therefore lowered paramagnetic properties due to hyperperfusion of the ictal region. Therefore as a non contrast sequence, SWI might be useful to detect a focal ictal area in SE/NSCE prior to contrast application. In addition, the diagnosis of an ictal activity in combination with DSCE and DWI and can differentiate these two from acute stroke due to the characteristic cortical vein appearance, which is contrary to the appearance in acute stroke or (hemiplegic) migraine. Personal information References MRI findings in aphasic status epilepticus; Toledo M et al.; Epilepsia 008 Aug; 49(8): Cortical regional hyperperfusion in nonconvulsive status epilepticus measured by dynamic brain perfusion CT; Hauf et al.; AJNR Am J Neuroradiol. 009 Apr; 30 (4):693-8 Postictal deficit mimicking stroke: role of perfusion CT; Masterson K et al.; J Neuroradiol. 009 Mar; 36 (1):48-51 Diffusion-weighted and perfusion MRI demonstrates parenchymal changes in complex partial status epilepticus. Szabo K et al. Brain 005 Jun; 18 (Pt 6): MRI findings in aphasic status epilepticus; Toledo M et al.; Epilepsia 008 Aug; 49(8): Cortical regional hyperperfusion in nonconvulsive status epilepticus measured by dynamic brain perfusion CT; Hauf et al.; AJNR Am J Neuroradiol. 009 Apr; 30 (4):693-8 Postictal deficit mimicking stroke: role of perfusion CT; Masterson K et al.; J Neuroradiol. 009 Mar; 36 (1):48-51 Diffusion-weighted and perfusion MRI demonstrates parenchymal changes in complex partial status epilepticus. Szabo K et al. Brain 005 Jun; 18 (Pt 6): Diminished Visibility of Cerebral Venous Vasculature in Subclinical Status Epilepticus by susceptibility-weighted imaging: A case report; Lee YL et al. Clin Neuroradiol /s Page 10 of 11

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