Martin Ritter

Roche (Switzerland)

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Rainer Dziewas

Klinikum Osnabrück

E. Bernd Ringelstein

University of Münster

Ralf Dittrich

Marienhospital Osnabrück

Dirk W. Droste

Centre Hospitalier de Luxembourg

E. Bernd Ringelstein

University of Münster

Ralf Dittrich

Comprehensive Cancer Center Erlangen

Darius G. Nabavi

Vivantes Klinikum

Darius G. Nabavi

Vivantes Klinikum

Walter Heindel

University Hospital Münster

Wolf R. Schäbitz

Evangelisches Krankenhaus Bielefeld

Cooperative Institutions

Heidelberg University

196

University Hospital Münster

168

University of Münster

168

University Hospital Heidelberg

167

Klinik und Poliklinik für Neurologie

157

Inserm

122

Charité - Universitätsmedizin Berlin

116

University of Melbourne

102

Health and Education Research Management and Epidemiologic Services (United States)

101

Universität Hamburg

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Benefit of Echocontrast-Enhanced Transcranial Arterial Color-Coded Duplex Ultrasound

Cerebrovascular Diseases (2005)

Dirk W. Droste Thomas Boehm Martin Ritter Ralf Dittrich E B Ringelstein

Proper assessment of the intracranial arteries by transcranial color-coded duplex sonography (TCCD) is occasionally made difficult by an insufficient temporal bone window, an unfavorable insonation angle, or low flow velocity or volume. In these cases, echocontrast could be helpful to increase the diagnostic confidence or to make the diagnosis at all.We investigated 67 temporal windows of 47 patients with insufficient native transtemporal insonation conditions before and after the application of the second-generation (gas-filled) microbubble contrast agent Sonovue (in 20 patients out of these 47, both temporal windows were insufficient, in the remaining 27 only one side).As compared to the precontrast scans, echocontrast allowed for more segments to be evaluated by pulsed Doppler sonography (p < 0.0001) and for longer lumen segments to be displayed on color mode (p < 0.0001). With the help of contrast medium, flow velocity in the middle cerebral artery could be measured through 65 windows as compared to only 26 windows before contrast was applied (p < 0.0001).In patients with poor precontrast visualization of intracranial arteries, echocontrast-enhanced TCCD is very helpful.

Lumen (anatomy)

Transcranial Doppler

10.1159/000087933

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Citations (22)

EUSI News

Cerebrovascular Diseases (2007)

Jan‐Hendrik Buhk Pawel Kermer Jennifer Frontera John Pile–Spellman J.P. Mohr

10.1159/000105243

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Citations (1)

On the origin of microembolic signals

Journal of Neurology (2003)

Gernot Schulte‐Altedorneburg Eun-Mi Nam Martin Ritter Tünde Magyar Ralf Dittrich

Transcranial Doppler

Neuroradiology

10.1007/s00415-003-0140-2

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Citations (11)

Sonografisches Neuromonitoring auf der Stroke Unit und in der neurologischen Intensivmedizin

Klinische Neurophysiologie (2022)

Felix Schlachetzki Max Nedelmann Jens Eyding Martin Ritter Ulf Schminke

Zusammenfassung Hintergrund Der Artikel gibt einen Überblick über die aktuellen diagnostischen Einsatzmöglichkeiten sonographischer Anwendung in der neurologischen Intensivmedizin. Methoden Selektive Literaturrecherche mit kritischer Beurteilung ab dem Jahr 1984 sowie nationaler und internationaler Leitlinien sowie Expertenmeinung. Ergebnisse Neben der raschen validen Abklärung akuter Schlaganfälle bieten verschiedene neurosonografische Monitoring-verfahren gerade in der Intensivmedizin spezifische Vorteile wie die beliebig häufige Wiederholbarkeit am Patientenbett selbst und die Darstellung in Echtzeit. Innovative Entwicklungen machen die Neurosonografie auch wissenschaftlich zu einem interessanten Gebiet. Schlussfolgerung Die neurosonografische Diagnostik nimmt seit Jahren einen wichtigen Stellenwert in der neurologischen Intensivmedizin ein. Weitere Anstrengungen sind notwendig, um die Verbreitung der Methode zu fördern und durch wissenschaftliche Evidenz zu stärken.

10.1055/a-1810-0728

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Citations (1)

Die kontrastmittelverstärkte transkranielle Doppler-Sonographie in der Diagnostik von Rechts-links-Shunts

Klinische Neurophysiologie (2002)

Martin Ritter Ralf Dittrich Dirk W. Droste

Paradoxe Hirnembolien über kardiale oder extrakardiale Rechts-links-Shunts sind eine häufig verkannte Ursache des ischämischen Insults bei jungen Erwachsenen unter 50 Jahren. Kardiale Rechts-links-Shunts können mittels transösophagealer Echokardiographie oder transkranieller Doppler-Sonographie identifiziert werden. Hierzu sind die Gabe intravenöser Ultraschallkontrastmittel und die Durchführung eines Provokationsmanövers zur Umkehr des intrakardialen Druckgefälles zwischen rechtem und linkem Kreislauf notwendig. Bislang vorliegende Studien verwendeten bei der Durchführung der Untersuchung teilweise unterschiedliche Kontrastmittel, wählten verschiedene Zeitpunkte zur Durchführung des Shunt-Provokationsmanövers nach Injektion des Kontrastmittels und benutzten uneinheitliche Auswertekriterien. Der vorliegende Artikel beleuchtet die Vor- und Nachteile dieser unterschiedlichen Verfahrensweisen und soll Hilfestellungen zur bestmöglichen praktischen Durchführung geben.

10.1055/s-2002-32778

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Thalamic involvement in patients with neurologic impairment due to Shiga toxin 2

Annals of Neurology (2012)

Sven G. Meuth Kerstin Göbel Tatyana Kanyshkova Petra Ehling Martin Ritter

Objective The outbreak of hemolytic–uremic syndrome and diarrhea caused by Shiga toxin–producing Escherichia coli O104:H4 in Germany during May to July 2011 involved severe and characteristic neurologic manifestations with a strong female preponderance. Owing to these observations, we designed a series of experimental studies to evaluate the underlying mechanism of action of this clinical picture. Methods A magnetic resonance imaging and electroencephalographic study of patients was performed to evaluate the clinical picture in detail. Thereafter, combinations of different experimental settings, including electrophysiological and histological analyses, as well as calcium imaging in brain slices of rats, were conducted. Results We report on 7 female patients with neurologic symptoms and signs including bilateral thalamic lesions and encephalopathic changes indicative of a predominant involvement of the thalamus. Experimental studies in rats revealed an enhanced expression of the Shiga toxin receptor globotriaosylceramide on thalamic neurons in female rats as compared to other brain regions in the same rats and to male animals. Incubation of brain slices with Shiga toxin 2 evoked a strong membrane depolarization and intracellular calcium accumulation in neurons, associated with neuronal apoptosis, predominantly in the thalamic area. Interpretation These findings suggest that the direct cytotoxic effect of Shiga toxin 2 in the thalamus might contribute to the pathophysiology of neuronal complications in hemolytic–uremic syndrome. ANN NEUROL 2013;73:419–429

Pathophysiology

10.1002/ana.23814

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Citations (17)

Author Index Vol. 49, 2003

European Neurology (2003)

R.M. Antonello L. Capus Manuela Gioulis Sandro Zambito Marsala G. Cazzato

10.1159/000071036

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Vascularization of carotid plaque in recently symptomatic patients is associated with the occurrence of transcranial microembolic signals

European Journal of Neurology (2012)

Martin Ritter K. Theismann Meilin Schmiedel E. Bernd Ringelstein Ralf Dittrich

Microembolic signals (MES) are detectable in the middle cerebral artery by transcranial ultrasound downstream to atherosclerotic lesions of the internal carotid artery (ICA) in patients with stroke or transient ischaemic attack. The occurrence of MES predicts future risk of stroke in patients with symptomatic and asymptomatic carotid stenosis. The detection of intra-plaque neo-vascularization by contrast-enhanced ultrasound (CEUS) in atherosclerotic plaques of the ICA is associated with future cardiovascular/cerebrovascular events. We investigated whether there is an association between both surrogate markers of future vascular events.Forty-one patients with symptomatic atherosclerotic plaques underwent ipsilateral transcranial ultrasound MES detection for 30 min followed by a CEUS investigation of the plaque. The occurrence and number of MES was documented, and the degree of intra-plaque neo-vascularization was measured semi-quantitatively.During the 30 min investigation, 17 patients had MES and nine of them showed neo-vascularization of the atherosclerotic plaque. The remaining 24 patients did not have MES, and only in four patients of this group could plaque neo-vascularization be demonstrated (P = 0.020).We found an association between the occurrence of MES and the presence of neo-vascularization in patients with symptomatic atherosclerotic carotid plaque. Therefore, plaque neo-vascularization might also be a surrogate marker of future stroke risk.

Transcranial Doppler

10.1111/ene.12030

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Citations (35)

Development of a radioactive holmium-166 skin patch to treat skin cancer

Bulletin of the American Physical Society (2017)

Martin Ritter

Skin cancer is the most common form of cancer affecting over 3 million people per year in the US alone. The two most common forms of cancer, basal and squamous cell carcinoma, are easily removable if detected early and properly treated. These cancers can become deadly if allowed to spread. There currently exist multiple treatment options with varying success rates such as surgical excision and radiotherapy. However, these methods are not suited to treat sensitive areas such as the eyelids, nose, and lips. We propose a holmium based radioactive skin patch to achieve locally therapeutic radiation doses with no damage to underlying tissues. Holmium-166 is a beta emitter produced by a neutron capture by holmium-165 with a maximum energy of 1.8 MeV and a half-life of 26.84 hours. The half-life of the holmium-166 allows production of the patches off-site and the radiation type deposits over 90\% of the dose within the first 2 mm of skin. We used DC sputtering to deposit a thin film of holmium on a Kapton substrate and characterized the thickness and uniformity of the film with a scanning electron microscope. We activated the holmium at the 1 MW TRIGA reactor located at the Federal Center in Lakewood, CO and achieved activities of up to 1 mCi, an activity within the range for therapeutic treatment. Our final samples showed close agreement between prediction and measurement with predicted activities of 750 $\pm$ 35 $\mu$Ci and 967 $\pm$ 35 $\mu$Ci and measured activities of 760 $\pm$ 42 $\mu$Ci and 985 $\pm$ 54 $\mu$Ci respectively.

Holmium

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Fiberoptic Endoscopic Dysphagia Severity Scale Predicts Outcome after Acute Stroke

Cerebrovascular Diseases (2009)

Tobias Warnecke Martin Ritter Bjelka Kröger Stephan Oelenberg Inga Teismann

Fiberoptic endoscopic evaluation of swallowing (FEES) is a suitable method for dysphagia assessment after acute stroke. Recently, we developed the fiberoptic endoscopic dysphagia severity scale (FEDSS) for acute stroke patients, grading dysphagia into 6 severity codes (1 to 6; 1 being best). The purpose of this study was to investigate the impact of the FEDSS as a predictor of outcomes at 3 months and intermediate complications during acute treatment.A total of 153 consecutive first-ever acute stroke patients were enrolled. Dysphagia was classified according to the FEDSS, assessed within 24 h after admission. Intermediate outcomes were pneumonia and endotracheal intubation. Functional outcome was measured by the modified Rankin Scale (mRS) at 3 months. Multivariate regression analysis was used to identify whether the FEDSS was an independent predictor of outcome and intercurrent complications. Analyses were adjusted for sex, age and National Institutes of Health Stroke Scale (NIH-SS) on admission.The FEDSS was found to predict the mRS at 3 months as well as but independent from the NIH-SS. For each additional point on the FEDSS, the likelihood of dependency at 3 months (mRS > or = 3) raised by approximately 50%. Each increase of 1 point on the FEDSS conferred a more than 2-fold increased chance of developing pneumonia. The odds for the necessity of endotracheal intubation raised by a factor of nearly 2.5 with each additional point on the FEDSS.The FEDSS strongly and independently predicts outcome and intercurrent complications after acute stroke. Thus, a baseline FEES examination provides valuable prognostic information for the treatment of acute stroke patients.

Stroke

Acute stroke

10.1159/000228711

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Citations (132)