Jan H. Schaefer

Dr. Jan H. Schaefer


Research Focus & Metrics

Academic Career Length

8Years (2019-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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8 March 2022 in Neurology Neuroimmunology & Neuroinflammation
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MSMartin Schaller-Paule
Martin Schaller-Paule
YYYavor Yalachkov
Yavor Yalachkov
HSHelmuth Steinmetz
Helmuth Steinmetz
LFLucie Friedauer
Lucie Friedauer
EHElke Hattingen
Elke Hattingen
CFChristian Foerch
Christian Foerch
Background and Objectives Proteins of the coagulation system contribute to autoimmune inflammation in patients with multiple sclerosis (MS). On blood-brain barrier (BBB) disruption, fibrinogen enters the CNS and is rapidly converted to fibrin, unfolding pleiotropic autoimmune mechanisms. Fibrin accumulation leads to subsequent proteolytic degradation that results in D-dimer generation. The primary objective of this study was to determine intrathecal levels of D-dimer in CSF as a measure of intrathecal coagulation cascade activation and to evaluate its diagnostic utility in patients with MS in contrast to healthy subjects. Key secondary objectives included analysis of CSF D-dimer in differential diagnoses of MS and its relation to routine clinical markers of disease activity. Methods Patients admitted for the assessment of suspected MS were prospectively recruited from October 2017 to December 2020. Blood plasma and citrated CSF samples were analyzed using a highly sensitive luminescent oxygen channeling immunoassay. Intrathecal generation of D-dimer was analyzed by adjusting for CSF/serum albumin (Qalb) and CSF/plasma D-dimer quotients (QD-dimer), and corresponding CSF fibrinogen levels were determined. Final diagnoses after full evaluation and clinical data were recorded. Results Of 187 patients, 113 patients received a diagnosis of MS or clinically/radiologically isolated syndrome. We found increased intrathecal CSF D-dimer generation levels (QD-dimer/Qalb-index) for patients with relapsing-remitting MS (RRMS; n = 71, median 4.7, interquartile range [IQR] 2.5–8.0) when compared with those for disease controls (n = 22, median 2.6, IQR 2.1–4.8, p = 0.031). Absolute CSF D-dimer values correlated with CSF fibrinogen levels (r = 0.463; p < 0 .001) and CSF leukocytes (r = 0.273; p = 0.003) and were elevated in MS patients with contrast enhancement (CE) compared with MS patients without CE on MRI (n = 48, median 6 ng/mL, and IQR 3–15.25 vs n = 41, median 4 ng/mL, and IQR 2–7; p = 0.026). Exploratory subgroup analyses indicated a correlation of intrathecal inflammatory activity and CSF D-dimer levels. Discussion D-dimer in CSF can be reliably determined and correlates with markers of CNS inflammation and CSF fibrinogen levels. Adjusted for BBB dysfunction, CSF D-dimer may allow the identification of intrathecal coagulation cascade activation in patients with MS. Classification of Evidence This study provides Class I evidence that CSF D-dimer levels are elevated in patients with RRMS.

23 August 2022 in Frontiers in Neurology
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Journal Article
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JSJan H. Schaefer
Jan H. Schaefer
NKNatalia Kurka
Natalia Kurka
FKFee Keil
Fee Keil
MWMarlies Wagner
Marlies Wagner
HSHelmuth Steinmetz
Helmuth Steinmetz
FBFerdinand O. Bohmann
Ferdinand O. Bohmann
Background: Endovascular therapy (EVT) in acute ischemic stroke has been widely established. Globally, stroke patients are transferred either directly to a thrombectomy center (DC) or a peripheral stroke unit with a “drip-and-ship” (DS) model. We aimed to determine differences between the DS and DC paradigms after EVT of acute stroke patients with large-vessel-occlusion (LVO) in the database of the German Stroke Registry (GSR).Methods: We performed a retrospective analysis of GSR patients between June 2015 and December 2019 in 23 German centers. Primary outcome was an ordinal shift analysis of modified Rankin Scale (mRS) 90 days after index event. Secondary endpoints included time from symptom onset to recanalization and complications. Tertiary endpoint was the association of imaging strategies in DS admissions with outcome.Results: 2,813 patients were included in the DS and 3,819 in the DC group. After propensity score matching mRS after 90 days was higher in DS than DC admissions (OR 1.26; 95%-CI 1.13–1.40). Time from symptom-onset to flow-restoration was shorter in DC than DS (median 199.0 vs. 298.0 min; p < 0.001). DS patients undergoing magnetic resonance imaging (MRI; n=183) before EVT had a lower 90-day mRS than without (n = 944) (OR 0.63; 95%-CI 0.45–0.88). ASPECTS assessed on MRI correlated with 90-day mRS (ρ = −0.326; p < 0.001).Conclusions: Clinical outcome was worse for EVT-eligible patients in the DS setting, even though patients were in a better state of health prior to stroke. A potentially mutable factor was the time delay of 99 min from symptom-onset to successful recanalization. Performing MRI before thrombectomy was associated with good outcome and MRI-ASPECTS was negatively correlated with mRS after 90 days.

Verified
Journal Article
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KKKimberly Koerbel
Kimberly Koerbel
YYYavor Yalachkov
Yavor Yalachkov
TRTabea Rotter
Tabea Rotter
MSMartin Schaller-Paule
Martin Schaller-Paule
JSJan H. Schaefer
Jan H. Schaefer
MMMichelle Maiworm
Michelle Maiworm
Impaired renal function can influence biomarker levels through mechanisms involving blood–brain barrier integrity and clearance pathways; however, the impact of variations within normal renal function remains unclear. The main aim of this study was to determine whether adjustment for the specific level of renal function is necessary when renal function remains within physiological levels. We studied n = 183 patients (NID n = 122; other neurological diseases n = 39; somatoform controls n = 22) who underwent lumbar puncture at University Hospital Frankfurt. Serum and cerebrospinal fluid (CSF) levels of neurofilament light chain (NfL), glial fibrillary acidic protein (GFAP), total tau protein (tTAU), and ubiquitin C-terminal hydrolase-L1 (UCHL1) were measured using the single molecule array (SIMOA) technique. Estimated glomerular filtration rate (eGFR) correlated negatively with CSF GFAP (r = −0.217, p = 0.004) and serum NfL (r = −0.164, p = 0.032). Patients with impaired renal function exhibited higher CSF NfL (p = 0.036) and CSF GFAP (p = 0.026) levels. However, these findings did not remain significant after adjusting for BMI and age. Importantly, in patients with normal renal function, no significant correlations with eGFR and biomarker levels were observed after adjustment. Our findings indicate that serum and CSF concentrations of NfL, GFAP, tTAU, and UCHL1 are not significantly affected by fluctuations in physiological kidney function but emphasize the importance of considering comorbidities in impaired renal function when interpreting biomarker levels.

1 October 2023 in Stroke
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Journal Article
Closed access
SWSae-Yeon Won
Sae-Yeon Won
RMRuzanna Melkonian
Ruzanna Melkonian
BBBedjan Behmanesh
Bedjan Behmanesh
JBJoshua Bernstock
Joshua Bernstock
MCMarcus Czabanka
Marcus Czabanka
FGFlorian Gessler
Florian Gessler
BACKGROUND: Several individual predictors for outcomes in patients with cerebellar stroke (CS) have been previously identified. There is, however, no established clinical score for CS. Therefore, the aim of this study was to develop simple and accurate grading scales for patients with CS in an effort to better estimate mortality and outcomes. METHODS: This multicentric retrospective study included 531 patients with ischemic CS presenting to 5 different academic neurosurgical and neurological departments throughout Germany between 2008 and 2021. Logistic regression analysis was performed to determine independent predictors related to 30-day mortality and unfavorable outcome (modified Rankin Scale score of 4–6). By weighing each parameter via calculation of regression coefficients, an ischemic CS-score and CS-grading scale (CS-GS) were developed and internally validated. RESULTS: Independent predictors for 30-day mortality were aged ≥70 years (odds ratio, 5.2), Glasgow Coma Scale score 3 to 4 at admission (odds ratio, 2.6), stroke volume ≥25 cm 3 (odds ratio, 2.7), and involvement of the brain stem (odds ratio, 3.9). When integrating each parameter into the CS-score, age≥70 years and brain stem stroke were assigned 2 points, Glasgow Coma Scale score 3 to 4, and stroke volume≥25 cm 3 1 point resulting in a score ranging from 0 to 6. CS-score of 0, 1, 2, 3, 4, 5, and 6 points resulted in 30-day mortality of 1%, 6%, 6%, 17%, 21%, 55%, and 67%, respectively. Independent predictors for 30-day unfavorable outcomes consisted of all components of the CS-score with an additional variable focused on comorbidities (CS-GS). Except for Glasgow Coma Scale score 3 to 4 at admission, which was assigned 3 points, all other parameters were assigned 1 point resulting in an overall score ranging from 0 to 7. CS-GS of 0, 1, 2, 3, 4, 5, 6, and 7 points resulted in 30-day unfavorable outcome of 1%, 17%, 33%, 40%, 50%, 80%, 77%, and 100%, respectively. Both 30-day mortality and unfavorable outcomes increased with increasing CS-score and CS-GS ( P <0.001). CONCLUSIONS: The CS-score and CS-GS are simple and accurate grading scales for the prediction of 30-day mortality and unfavorable outcome in patients with CS. While the score systems proposed here may not directly impact treatment decisions, it may help discuss mortality and outcome with patients and caregivers.

29 May 2023 in European Journal of Neurology
Verified
Journal Article
Open access
JSJan H. Schaefer
Jan H. Schaefer
MSMartin A. Schaller‐Paule
Martin A. Schaller‐Paule
KWKatharina Wenger
Katharina Wenger
CMChristoph Mayer
Christoph Mayer
UMUlrike Mann
Ulrike Mann
CFChristian Foerch
Christian Foerch
Background: The presence of contrast enhancement (CE) on magnetic resonance imaging (MRI) is one of the principal criteria for diagnosis and disease activity of multiple sclerosis (MS). Therefore, MS patients are frequently exposed to contrast agents, which may cause deposition in the brain, restricting its use in repeat examinations. Thus, serum biomarkers may be valuable as surrogate parameters to evaluate MS activity.Methods: REDUCE‐GAD was a prospective, multicentric, biobanking study to determine whether established serum markers (neurofilament light chain [NfL], glial fibrillary acidic protein [GFAP], tau protein, ubiquitin‐carboxyl‐terminal‐hydrolase (UCH‐L1), S100B and matrix‐metalloproteinase 9 [MMP9]) are predictive of CE‐positive MRI lesions. Blood samples were obtained from patients undergoing MRI 5 days before or after collection.Results: Patients (N = 102) from four different centers with confirmed MS or related disorders were included; n = 57 (55.9%) showed CE on MRI versus n = 45 (44.1%) without CE. Only higher NfL values indicated CE (odds ratio [OR] 1.05; 95% CI 1.0–1.09) and were correlated with number (ρ = 0.47; p < 0.001) and diameter of CE lesions (ρ = 0.58; p < 0.001). Nfl Z‐scores improved diagnostic accuracy (OR 1.52; 95% CI 1.06–2.18). Receiver operator characteristic analysis revealed a reasonable cut‐off value for NfL at 14.1 pg/mL (sensitivity 49.1%; specificity 82.2%; positive predictive value 77.8%; negative predictive value 56.0%). NfL ≥59.2 pg/mL was exclusively observed in patients with CE.Conclusions: Evaluation of several possible serum biomarkers for CE in MS patients provided the most robust results for NfL, particularly as Z‐scores. Following further evaluation, biomarkers may help stratify the application of contrast agents for brain imaging in MS patients.

1 September 2020 in European Stroke Journal
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Journal Article
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JSJan H. Schaefer
Jan H. Schaefer
CSChristoph Stephan
Christoph Stephan
CFChristian Foerch
Christian Foerch
WPWaltraud Pfeilschifter
Waltraud Pfeilschifter
Introduction: The global incidence of ischemic stroke among patients with human immunodeficiency virus is increasing. The aim of this controlled case analysis was to study patient characteristics, stroke etiologies, and risk factors in human immunodeficiency virus-positive patients in a medical system with easy access to antiretroviral therapies. Patients and methods: We conducted a retrospective, observational study of human immunodeficiency virus-positive patients treated in our stroke unit and outpatient clinic in Germany between 2012 and 2018. A control group of all patients treated for acute ischemic stroke in 2018 was used to elicit possible differences in stroke localization, etiology, and distribution of risk factors. Results: Out of 3615 patients with an acute ischemic stroke, 24 (0.7%) were newly or previously diagnosed as human immunodeficiency virus-positive. Strokes in this cohort were caused by large-vessel disease (37.5%), small-vessel disease (20.8%), cryptogenic-embolism (20.8%), vasculitis (16.7%), and cardio-embolism (4.2%). Large-vessel disease-related strokes were more often located in the posterior circulation (77.8%). Compared to the control group, cardio-embolic strokes were less and vasculitis and large-vessel disease more frequent. Human immunodeficiency virus-positive patients were younger at stroke onset (53.7 ± 12.8 vs. 70.2 ± 14.6 years, p = 0.05). Discussion: Although the prevalence of human immunodeficiency virus-infection among patients treated for acute ischemic strokes appears low, this collective merits special attention due to a high burden of potentially modifiable risk factors and vasculitis. Conclusion: Compared to previous studies, age at stroke onset was one of the highest, supporting the hypothesis that as antiretroviral therapy increases the life expectancy of people living with HIV/AIDS, they will be increasingly affected by cardiovascular disease. Human immunodeficiency virus-related cerebral vasculitis was associated with high mortality (75%).