@article{KraemerSchuhmannVolkmannetal.2022,
  author    = {Kr{\"a}mer, Stefanie D. and Schuhmann, Michael K. and Volkmann, Jens and Fluri, Felix},
  title     = {Deep brain stimulation in the subthalamic nucleus can improve skilled Forelimb movements and retune dynamics of striatal networks in a rat stroke model},
  series = {International Journal of Molecular Sciences},
  volume    = {23},
  journal   = {International Journal of Molecular Sciences},
  number    = {24},
  doi       = {10.3390/ijms232415862},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-312828},
  year      = {2022},
  abstract  = {Recovery of upper limb (UL) impairment after stroke is limited in stroke survivors. Since stroke can be considered as a network disorder, neuromodulation may be an approach to improve UL motor dysfunction. Here, we evaluated the effect of high-frequency stimulation (HFS) of the subthalamic nucleus (STN) in rats on forelimb grasping using the single-pellet reaching (SPR) test after stroke and determined costimulated brain regions during STN-HFS using 2-[\(^{18}\)F]Fluoro-2-deoxyglucose-([\(^{18}\)F]FDG)-positron emission tomography (PET). After a 4-week training of SPR, photothrombotic stroke was induced in the sensorimotor cortex of the dominant hemisphere. Thereafter, an electrode was implanted in the STN ipsilateral to the infarction, followed by a continuous STN-HFS or sham stimulation for 7 days. On postinterventional day 2 and 7, an SPR test was performed during STN-HFS. Success rate of grasping was compared between these two time points. [\(^{18}\)F]FDG-PET was conducted on day 2 and 3 after stroke, without and with STN-HFS, respectively. STN-HFS resulted in a significant improvement of SPR compared to sham stimulation. During STN-HFS, a significantly higher [\(^{18}\)F]FDG-uptake was observed in the corticosubthalamic/pallidosubthalamic circuit, particularly ipsilateral to the stimulated side. Additionally, STN-HFS led to an increased glucose metabolism within the brainstem. These data demonstrate that STN-HFS supports rehabilitation of skilled forelimb movements, probably by retuning dysfunctional motor centers within the cerebral network.},
  language  = {en}
}
@article{SchuhmannPappStolletal.2021,
  author    = {Schuhmann, Michael K. and Papp, Lena and Stoll, Guido and Blum, Robert and Volkmann, Jens and Fluri, Felix},
  title     = {Mesencephalic electrical stimulation reduces neuroinflammation after photothrombotic stroke in rats by targeting the cholinergic anti-inflammatory pathway},
  series = {International Journal of Molecular Sciences},
  volume    = {22},
  journal   = {International Journal of Molecular Sciences},
  number    = {3},
  issn      = {1422-0067},
  doi       = {10.3390/ijms22031254},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-259099},
  year      = {2021},
  abstract  = {Inflammation is crucial in the pathophysiology of stroke and thus a promising therapeutic target. High-frequency stimulation (HFS) of the mesencephalic locomotor region (MLR) reduces perilesional inflammation after photothrombotic stroke (PTS). However, the underlying mechanism is not completely understood. Since distinct neural and immune cells respond to electrical stimulation by releasing acetylcholine, we hypothesize that HFS might trigger the cholinergic anti-inflammatory pathway via activation of the α7 nicotinic acetylcholine receptor (α7nAchR). To test this hypothesis, rats underwent PTS and implantation of a microelectrode into the MLR. Three hours after intervention, either HFS or sham-stimulation of the MLR was applied for 24 h. IFN-γ, TNF-α, and IL-1α were quantified by cytometric bead array. Choline acetyltransferase (ChAT)\(^+\) CD4\(^+\)-cells and α7nAchR\(^+\)-cells were quantified visually using immunohistochemistry. Phosphorylation of NFĸB, ERK1/2, Akt, and Stat3 was determined by Western blot analyses. IFN-γ, TNF-α, and IL-1α were decreased in the perilesional area of stimulated rats compared to controls. The number of ChAT\(^+\) CD4\(^+\)-cells increased after MLR-HFS, whereas the amount of α7nAchR\(^+\)-cells was similar in both groups. Phospho-ERK1/2 was reduced significantly in stimulated rats. The present study suggests that MLR-HFS may trigger anti-inflammatory processes within the perilesional area by modulating the cholinergic system, probably via activation of the α7nAchR.},
  language  = {en}
}
@article{GabrielJirůHillmannKraftetal.2020,
  author    = {Gabriel, Katharina M. A. and J{\´i}rů-Hillmann, Steffi and Kraft, Peter and Selig, Udo and R{\"u}cker, Victoria and M{\"u}hler, Johannes and D{\"o}tter, Klaus and Keidel, Matthias and Soda, Hassan and Rascher, Alexandra and Schneider, Rolf and Pfau, Mathias and Hoffmann, Roy and Stenzel, Joachim and Benghebrid, Mohamed and Goebel, Tobias and Doerck, Sebastian and Kramer, Daniela and Haeusler, Karl Georg and Volkmann, Jens and Heuschmann, Peter U. and Fluri, Felix},
  title     = {Two years' experience of implementing a comprehensive telemedical stroke network comprising in mainly rural region: the Transregional Network for Stroke Intervention with Telemedicine (TRANSIT-Stroke)},
  series = {BMC Neurology},
  volume    = {20},
  journal   = {BMC Neurology},
  doi       = {10.1186/s12883-020-01676-6},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-229214},
  year      = {2020},
  abstract  = {Background Telemedicine improves the quality of acute stroke care in rural regions with limited access to specialized stroke care. We report the first 2 years' experience of implementing a comprehensive telemedical stroke network comprising all levels of stroke care in a defined region. Methods The TRANSIT-Stroke network covers a mainly rural region in north-western Bavaria (Germany). All hospitals providing acute stroke care in this region participate in TRANSIT-Stroke, including four hospitals with a supra-regional certified stroke unit (SU) care (level III), three of those providing teleconsultation to two hospitals with a regional certified SU (level II) and five hospitals without specialized SU care (level I). For a two-year-period (01/2015 to 12/2016), data of eight of these hospitals were available; 13 evidence-based quality indicators (QIs) related to processes during hospitalisation were evaluated quarterly and compared according to predefined target values between level-I- and level-II/III-hospitals. Results Overall, 7881 patients were included (mean age 74.6 years +/- 12.8; 48.4\% female). In level-II/III-hospitals adherence of all QIs to predefined targets was high ab initio. In level-I-hospitals, three patterns of QI-development were observed: a) high adherence ab initio (31\%), mainly in secondary stroke prevention; b) improvement over time (44\%), predominantly related to stroke specific diagnosis and in-hospital organization; c) no clear time trends (25\%). Overall, 10 out of 13 QIs reached predefined target values of quality of care at the end of the observation period. Conclusion The implementation of the comprehensive TRANSIT-Stroke network resulted in an improvement of quality of care in level-I-hospitals.},
  language  = {en}
}
@article{ElhfnawyAbdEl‐RaoufVolkmannetal.2020,
  author    = {Elhfnawy, Ahmed Mohamed and Abd El-Raouf, Mervat and Volkmann, Jens and Fluri, Felix and Elsalamawy, Doaa},
  title     = {Relation of infarction location and volume to vertigo in vertebrobasilar stroke},
  series = {Brain and Behavior},
  volume    = {10},
  journal   = {Brain and Behavior},
  number    = {3},
  doi       = {10.1002/brb3.1564},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-218047},
  year      = {2020},
  abstract  = {Objective Vertigo is a common presentation of vertebrobasilar stroke. Anecdotal reports have shown that vertigo occurs more often in multiple than in single brainstem or cerebellar infarctions. We examined the relation between the location and volume of infarction and vertigo in patients with vertebrobasilar stroke. Methods Consecutive patients with vertebrobasilar stroke were prospectively recruited. The infarction location and volume were assessed in the diffusion-weighted magnetic resonance imaging. Results Fifty-nine patients were included, 32 (54.2\%) with vertigo and 27 (45.8\%) without vertigo. The infarction volume did not correlate with National Institute of Health Stroke Scale (NIHSS) score on admission (Spearman ρ = .077, p = .56) but correlated with modified Rankin Scale (ρ = .37, p = .004) on discharge. In the vertigo group, the proportion of men was lower (53.1\% vs. 77.8\%, p = .049), fewer patients had focal neurological deficits (65.6\% vs. 96.3\%, p = .004), patients tended to present later (median [IQR] was 7.5 [4-46] vs. 4 [2-12] hours, p = .052), numerically fewer patients received intravenous thrombolysis (15.6\% vs. 37\%, p = .06), and the total infarction volume was larger (5.6 vs. 0.42 cm3, p = .008) than in nonvertigo group. In multivariate logistic regression, infarction location either in the cerebellum or in the dorsal brainstem (odds ratio [OR] 16.97, 95\% CI 3.1-92.95, p = .001) and a total infarction volume of >0.48 cm3 (OR 4.4, 95\% CI 1.05-18.58, p = .043) were related to vertigo. In another multivariate logistic regression, after adjusting for age, sex, intravenous thrombolysis, serum level of white blood cells, and atrial fibrillation, vertigo independently predicted a total infarction volume of >0.48 cm3 (OR 5.75, 95\% CI 1.43-23.08, p = .01). Conclusion Infarction location in the cerebellum and/or dorsal brainstem is an independent predictor of vertigo. Furthermore, larger infarction volume in these structures is associated with vertigo. A considerable proportion of patients with vascular vertigo present without focal neurological deficits posing a diagnostic challenge. National Institute of Health Stroke Scale is not sensitive for vertebrobasilar stroke.},
  language  = {en}
}
@article{SchuhmannStollBohretal.2019,
  author    = {Schuhmann, Michael K. and Stoll, Guido and Bohr, Arne and Volkmann, Jens and Fluri, Felix},
  title     = {Electrical stimulation of the mesencephalic locomotor region attenuates neuronal loss and cytokine expression in the perifocal region of photothrombotic stroke in rats},
  series = {International Journal of Molecular Science},
  volume    = {20},
  journal   = {International Journal of Molecular Science},
  number    = {9},
  issn      = {1422-0067},
  doi       = {10.3390/ijms20092341},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-201355},
  year      = {2019},
  abstract  = {Deep brain stimulation of the mesencephalic locomotor region (MLR) improves the motor symptoms in Parkinson's disease and experimental stroke by intervening in the motor cerebral network. Whether high-frequency stimulation (HFS) of the MLR is involved in non-motor processes, such as neuroprotection and inflammation in the area surrounding the photothrombotic lesion, has not been elucidated. This study evaluates whether MLR-HFS exerts an anti-apoptotic and anti-inflammatory effect on the border zone of cerebral photothrombotic stroke. Rats underwent photothrombotic stroke of the right sensorimotor cortex and the implantation of a microelectrode into the ipsilesional MLR. After intervention, either HFS or sham stimulation of the MLR was applied for 24 h. The infarct volumes were calculated from consecutive brain sections. Neuronal apoptosis was analyzed by TUNEL staining. Flow cytometry and immunohistochemistry determined the perilesional inflammatory response. Neuronal apoptosis was significantly reduced in the ischemic penumbra after MLR-HFS, whereas the infarct volumes did not differ between the groups. MLR-HFS significantly reduced the release of cytokines and chemokines within the ischemic penumbra. MLR-HFS is neuroprotective and it reduces pro-inflammatory mediators in the area that surrounds the photothrombotic stroke without changing the number of immune cells, which indicates that MLR-HFS enables the function of inflammatory cells to be altered on a molecular level.},
  language  = {en}
}
@article{SchuhmannStollPappetal.2019,
  author    = {Schuhmann, Michael K. and Stoll, Guido and Papp, Lena and Bohr, Arne and Volkmann, Jens and Fluri, Felix},
  title     = {Electrical stimulation of the mesencephalic locomotor region has no impact on blood-brain barrier alterations after cerebral photothrombosis in rats},
  series = {International Journal of Molecular Science},
  volume    = {20},
  journal   = {International Journal of Molecular Science},
  number    = {16},
  issn      = {1422-0067},
  doi       = {10.3390/ijms20164036},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-201284},
  year      = {2019},
  abstract  = {Blood-brain barrier (BBB) disruption is a critical event after ischemic stroke, which results in edema formation and hemorrhagic transformation of infarcted tissue. BBB dysfunction following stroke is partly mediated by proinflammatory agents. We recently have shown that high frequency stimulation of the mesencephalic locomotor region (MLR-HFS) exerts an antiapoptotic and anti-inflammatory effect in the border zone of cerebral photothrombotic stroke in rats. Whether MLR-HFS also has an impact on BBB dysfunction in the early stage of stroke is unknown. In this study, rats were subjected to photothrombotic stroke of the sensorimotor cortex and implantation of a stimulating microelectrode into the ipsilesional MLR. Thereafter, either HFS or sham stimulation of the MLR was applied for 24 h. After scarifying the rats, BBB disruption was assessed by determining albumin extravasation and tight junction integrity (claudin 3, claudin 5, and occludin) using Western blot analyses and immunohistochemistry. In addition, by applying zymography, expression of pro-metalloproteinase-9 (pro-MMP-9) was analyzed. No differences were found regarding infarct size and BBB dysfunction between stimulated and unstimulated animals 24 h after induction of stroke. Our results indicate that MLR-HFS neither improves nor worsens the damaged BBB after stroke. Attenuating cytokines/chemokines in the perilesional area, as mediated by MLR-HFS, tend to play a less significant role in preventing the BBB integrity.},
  language  = {en}
}
@article{ElhfnawyVolkmannSchliesseretal.2019,
  author    = {Elhfnawy, Ahmed Mohamed and Volkmann, Jens and Schliesser, Mira and Fluri, Felix},
  title     = {Symptomatic vs. asymptomatic 20-40\% internal carotid artery stenosis: Does the plaque size matter?},
  series = {Frontiers in Neurology},
  volume    = {10},
  journal   = {Frontiers in Neurology},
  number    = {960},
  doi       = {10.3389/fneur.2019.00960},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-201262},
  year      = {2019},
  abstract  = {Background: Around 9-15\% of ischemic strokes are related to internal carotid artery (ICA)-stenosis ≥50\%. However, the extent to which ICA-stenosis <50\% causes ischemic cerebrovascular events is uncertain. We examined the relation between plaque cross-sectional area and length and the risk of ischemic stroke or TIA among patients with ICA-stenosis of 20-40\%. Methods: We retrospectively identified patients admitted to the Department of Neurology, University Hospital of W{\"u}rzburg, from January 2011 until September 2016 with ischemic stroke or TIA and concomitant ICA-stenosis of 20-40\%, either symptomatic or asymptomatic. Plaque length and cross-sectional area were assessed on ultrasound scans. Results: We identified 41 patients with ischemic stroke or TIA and ICA-stenosis of 20-40\%; 14 symptomatic and 27 asymptomatic. The plaque cross-sectional area was significantly larger among symptomatic than asymptomatic ICA-stenosis; median values (IQR) were 0.45 (0.21-0.69) cm2 and 0.27 (0.21-0.38) cm2, p = 0.03, respectively. A plaque cross-sectional area ≥0.36 cm2 had a sensitivity of 71\% and a specificity of 76\% for symptomatic compared with asymptomatic ICA-stenosis. In a sex-adjusted multivariate logistic regression, a plaque cross-sectional area ≥0.36 cm2 and a plaque length ≥1.65 cm were associated with an OR (95\% CI) of 5.54 (1.2-25.6), p = 0.028 and 1.78 (0.36-8.73), p = 0.48, respectively, for symptomatic ICA-stenosis. Conclusion: Large plaques might increase the risk of ischemic stroke or TIA among patients with low-grade ICA-stenosis of 20-40\%. Sufficiently powered prospective longitudinal cohort studies are needed to definitively test the stroke risk stratification value of carotid plaque length and cross-sectional area in the setting of current optimal medical treatment.},
  language  = {en}
}
@article{ElhfnawyVolkmannSchliesseretal.2019,
  author    = {Elhfnawy, Ahmed Mohamed and Volkmann, Jens and Schliesser, Mira and Fluri, Felix},
  title     = {Are cerebral white matter lesions related to the presence of bilateral internal carotid artery stenosis or to the length of stenosis among patients with ischemic cerebrovascular events?},
  series = {Frontiers in Neurology},
  volume    = {10},
  journal   = {Frontiers in Neurology},
  number    = {919},
  doi       = {10.3389/fneur.2019.00919},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-201241},
  year      = {2019},
  abstract  = {Background and purpose: Previous studies delivered contradicting results regarding the relation between the presence of an internal carotid artery stenosis (ICAS) and the occurence of white matter lesions (WMLs). We hypothesize that special characteristics related to the ICAS might be related to the WMLs. We examined the relation between the presence of bilateral ICAS, the degree and length of stenosis and ipsi-, contralateral as well as mean white matter lesion load (MWMLL). Methods: In a retrospective cohort, patients with ischemic stroke or transient ischemic attack (TIA) as well as ipsi- and/or contralateral ICAS were identified. The length and degree of ICAS, as well as plaque morphology (hypoechoic, mixed or echogenic), were assessed on ultrasound scans and, if available, the length was also measured on magnetic resonance angiography (MRA) scans, and/or digital subtraction angiography (DSA). The WMLs were assessed in 4 areas separately, (periventricular and deep WMLs on each hemispherer), using the Fazekas scale. The MWMLL was calculated as the mean of these four values. Results: 136 patients with 177 ICAS were identified. A significant correlation between age and MWMLL was observed (Spearman correlation coefficient, ρ = 0.41, p < 0.001). Before adjusting for other risk factors, a significantly positive relation was found between the presence of bilateral ICAS and MWMLL (p = 0.039). The length but not the degree of ICAS showed a very slight trend toward association with ipsilateral WMLs and with MWMLL. In an age-adjusted multivariate logistic regression with MWMLL ≥2 as the outcome measure, atrial fibrillation (OR 3.54, 95\% CI 1.12-11.18, p = 0.03), female sex (OR 3.11, 95\% CI 1.19-8.11, p = 0.02) and diabetes mellitus (OR 2.76, 95\% CI 1.16-6.53, p = 0.02) were significantly related to WMLs, whereas the presence of bilateral stenosis showed a trend toward significance (OR 2.25, 95\% CI 0.93-5.45, p = 0.074). No relation was found between plaque morphology and MWMLL, periventricular, or deep WMLs. Conclusion: We have shown a slight correlation between the length of stenosis and the presence of WMLs which might be due to microembolisation originating from the carotid plaque. However, the presence of bilateral ICAS seems also to be related to WMLs which may point to common underlying vascular risk factors contributing to the occurrence of WML.},
  language  = {en}
}
@article{ElhfnawyHeuschmannPhametal.2019,
  author    = {Elhfnawy, Ahmed Mohamed and Heuschmann, Peter U. and Pham, Mirko and Volkmann, Jens and Fluri, Felix},
  title     = {Stenosis length and degree interact with the risk of cerebrovascular events related to internal carotid artery stenosis},
  series = {Frontiers in Neurology},
  volume    = {10},
  journal   = {Frontiers in Neurology},
  number    = {317},
  issn      = {1664-2295},
  doi       = {10.3389/fneur.2019.00317},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-196225},
  year      = {2019},
  abstract  = {Background and Purpose: Internal carotid artery stenosis (ICAS)≥70\% is a leading cause of ischemic cerebrovascular events (ICVEs). However, a considerable percentage of stroke survivors with symptomatic ICAS (sICAS) have <70\% stenosis with a vulnerable plaque. Whether the length of ICAS is associated with high risk of ICVEs is poorly investigated. Our main aim was to investigate the relation between the length of ICAS and the development of ICVEs. Methods: In a retrospective cross-sectional study, we identified 95 arteries with sICAS and another 64 with asymptomatic internal carotid artery stenosis (aICAS) among 121 patients with ICVEs. The degree and length of ICAS as well as plaque echolucency were assessed on ultrasound scans. Results: A statistically significant inverse correlation between the ultrasound-measured length and degree of ICAS was detected for sICAS≥70\% (Spearman correlation coefficient ρ = -0.57, p < 0.001, n = 51) but neither for sICAS<70\% (ρ = 0.15, p = 0.45, n = 27) nor for aICAS (ρ = 0.07, p = 0.64, n = 54). The median (IQR) length for sICAS<70\% and ≥70\% was 17 (15-20) and 15 (12-19) mm (p = 0.06), respectively, while that for sICAS<90\% and sICAS 90\% was 18 (15-21) and 13 (10-16) mm, respectively (p < 0.001). Among patients with ICAS <70\%, a cut-off length of ≥16 mm was found for sICAS rather than aICAS with a sensitivity and specificity of 74.1\% and 51.1\%, respectively. Irrespective of the stenotic degree, plaques of the sICAS compared to aICAS were significantly more often echolucent (43.2 vs. 24.6\%, p = 0.02). Conclusion: We found a statistically insignificant tendency for the ultrasound-measured length of sICAS<70\% to be longer than that of sICAS≥70\%. Moreover, the ultrasound-measured length of sICAS<90\% was significantly longer than that of sICAS 90\%. Among patients with sICAS≥70\%, the degree and length of stenosis were inversely correlated. Larger studies are needed before a clinical implication can be drawn from these results.},
  language  = {en}
}
@article{FluriSchuhmannKleinschnitz2015,
  author    = {Fluri, Felix and Schuhmann, Michael K and Kleinschnitz, Christoph},
  title     = {Animal models of ischemic stroke and their application in clinical research},
  series = {Drug Design, Development and Therapy},
  volume    = {9},
  journal   = {Drug Design, Development and Therapy},
  doi       = {10.2147/DDDT.S56071},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-149157},
  pages     = {3445-3454},
  year      = {2015},
  abstract  = {This review outlines the most frequently used rodent stroke models and discusses their strengths and shortcomings. Mimicking all aspects of human stroke in one animal model is not feasible because ischemic stroke in humans is a heterogeneous disorder with a complex pathophysiology. The transient or permanent middle cerebral artery occlusion (MCAo) model is one of the models that most closely simulate human ischemic stroke. Furthermore, this model is characterized by reliable and well-reproducible infarcts. Therefore, the MCAo model has been involved in the majority of studies that address pathophysiological processes or neuroprotective agents. Another model uses thromboembolic clots and thus is more convenient for investigating thrombolytic agents and pathophysiological processes after thrombolysis. However, for many reasons, preclinical stroke research has a low translational success rate. One factor might be the choice of stroke model. Whereas the therapeutic responsiveness of permanent focal stroke in humans declines significantly within 3 hours after stroke onset, the therapeutic window in animal models with prompt reperfusion is up to 12 hours, resulting in a much longer action time of the investigated agent. Another major problem of animal stroke models is that studies are mostly conducted in young animals without any comorbidity. These models differ from human stroke, which particularly affects elderly people who have various cerebrovascular risk factors. Choosing the most appropriate stroke model and optimizing the study design of preclinical trials might increase the translational potential of animal stroke models.},
  language  = {en}
}