Establishing an MSU service in a medium-sized German urban area-clinical and economic considerations.

Background and purpose: Mobile stroke units (MSU) have been demonstrated to improve prehospital stroke care in metropolitan and rural regions. Due to geographical, social and structural idiosyncrasies of the German city of Mannheim, concepts of established MSU services are not directly applicable to the Mannheim initiative. The aim of the present analysis was to identify major determinants that need to be considered when initially setting up a local MSU service. Methods: Local stroke statistics from 2015 to 2021 were analyzed and circadian distribution of strokes and local incidence rates were calculated. MSU patient numbers and total program costs were estimated for varying operating modes, daytime coverage models, staffing configurations which included several resource sharing models with the hospital. Additional case-number simulations for expanded catchment areas were performed. Results: Median time of symptom onset of ischemic stroke patients was 1:00 p.m. 54.3% of all stroke patients were admitted during a 10-h time window on weekdays. Assuming that MSU is able to reach 53% of stroke patients, the average expected number of ischemic stroke patients admitted to MSU would be 0.64 in a 10-h shift each day, which could potentially be increased by expanding the MSU catchment area. Total estimated MSU costs amounted to € 815,087 per annum. Teleneurological assessment reduced overall costs by 11.7%. Conclusion: This analysis provides a framework of determinants and considerations to be addressed during the design process of a novel MSU program in order to balance stroke care improvements with the sustainable use of scarce resources.

Lifetime economic potential of mobile stroke units in acute stroke care: A model-based analysis of the drivers of cost-effectiveness.

BACKGROUND AND PURPOSE: To simulate patient-level costs, analyze the economic potential of telemedicine-based mobile stroke units for acute prehospital stroke care, and identify major determinants of cost-effectiveness, based on two recent prospective trials from the United States and Germany. METHODS: A Markov decision model was developed to simulate lifetime costs and outcomes of mobile stroke unit. The model compares diagnostic and therapeutic pathways of ischemic stroke, hemorrhagic stroke, and stroke mimic patients by conventional care or by mobile stroke units. The treatment outcomes were derived from the B_PROUD and the BEST-mobile stroke unit trials and further input parameters were derived from recent literature. Uncertainty was addressed by deterministic and probabilistic sensitivity analyses. A lifetime horizon based on the US healthcare system was adopted to evaluate different cost thresholds for mobile stroke unit and the resulting cost-effectiveness. Willingness-to-pay thresholds were set at 1x and 3x gross domestic product per capita, as recommended by the World Health Organization. RESULTS: In the base case scenario, mobile stroke unit care yielded an incremental gain of 0.591 quality-adjusted life years per dispatch. Mobile stroke unit was highly cost-effective up to a maximum average cost of 43,067 US dollars per patient. Sensitivity analyses revealed that MSU cost-effectiveness is mainly affected by reduction of long-term disability costs. Also, among other parameters, the rate of stroke mimics patients diagnosed by MSU plays an important role. CONCLUSION: This study demonstrated that mobile stroke unit can possibly be operated on an excellent level of cost-effectiveness in urban areas in North America with number of stroke mimic patients and long-term stroke survivor costs as major determinants of lifetime cost-effectiveness.

Comparing Expert and Non-Expert Assessment of Patients Presenting with Neurological Symptoms to the Emergency Department: A Retrospective Observational Study.

OBJECTIVE: Referrals to neurology in emergency departments (ED) are continuously increasing, currently representing 15% of all admissions. Existing triage systems were developed for general medical populations and have not been validated for patients with neurological symptoms. METHODS: To characterize neurological emergencies, we first retrospectively analyzed symptoms, service times and resources of the cohort of neurological referrals to a German interdisciplinary ED (IED) during 2017 according to urgency determined by final IED diagnosis. In a second step, we performed a retrospective assignment of consecutive patients presenting in April 2017 according to internal guidelines as either acute (requiring diagnostic/therapeutic procedures within 24 hrs) or non-acute neurological conditions as well as a retrospective classification according to the Emergency Severity Index (ESI). Both assessments were compared with the urgency according to the final ER diagnosis. RESULTS: In a 12-month period, 36.4% of 5340 patients were rated as having an urgent neurological condition; this correlated with age, door-to-doctor time, imaging resource use and admission (p < 0.001, respectively). In a subset of 275 patients, 59% were retrospectively triaged as acute according to neurological expertise and 48% according to ESI categories 1 and 2. Neurological triage identified urgency with a significantly higher sensitivity (94.8, p < 0.01) but showed a significantly lower specificity (55.1, p < 0.05) when compared to ESI (80.5 and 65.2, respectively). CONCLUSION: The ESI may not take specific aspects of neurological emergency (eg, time-sensitivity) sufficiently into account. Refinements of existing systems or supplementation with dedicated neurological triage tools based on neurological expertise and experience may improve the triage of patients with neurological symptoms.

Individual Assessment of Brain Tissue Changes in MS and the Effect of Focal Lesions on Short-Term Focal Atrophy Development in MS: A Voxel-Guided Morphometry Study.

We performed voxel-guided morphometry (VGM) investigating the mechanisms of brain atrophy in multiple sclerosis (MS) related to focal lesions. VGM maps detect regional brain changes when comparing 2 time points on high resolution T1-weighted (T1w) magnetic resonace imaging (MRI). Two T1w MR datasets from 92 relapsing-remitting MS patients obtained 12 months apart were analysed with VGM. New lesions and volume changes of focal MS lesions as well as in the surrounding tissue were identified by visual inspection on colour coded VGM maps. Lesions were dichotomized in active and inactive lesions. Active lesions, defined by either new lesions (NL) (volume increase > 5% in VGM), chronic enlarging lesions (CEL) (pre-existent T1w lesions with volume increase > 5%), or chronic shrinking lesions (CSL) (pre-existent T1w lesions with volume reduction > 5%) in VGM, were accompanied by tissue shrinkage in surrounding and/or functionally related regions. Volume loss within the corpus callosum was highly correlated with the number of lesions in its close proximity. Volume loss in the lateral geniculate nucleus was correlated with lesions along the optic radiation. VGM analysis provides strong evidence that all active lesion types (NL, CEL, and CSL) contribute to brain volume reduction in the vicinity of lesions and/or in anatomically and functionally related areas of the brain.

Assessment of perfusion deficits in ischemic stroke using 3D-GRASE arterial spin labeling magnetic resonance imaging with multiple inflow times.

BACKGROUND AND PURPOSE: Arterial spin labeling (ASL) MRI provides information on tissue perfusion by consecutive readout of labeled blood captured in arteries or the microvasculature without using contrast agents. METHODS: We used a single-shot 3D acquisition and readout technique for ASL with multiple inflow times (TI) to evaluate hemodynamic compromise and dynamics of arterial blood inflow expressed by the bolus arrival time (BAT). Thirty-six patients with ischemic stroke were examined with a standard multimodal MRI protocol including dynamic susceptibility contrast (DSC) and multi-TI ASL perfusion imaging. Time-to-peak maps were used to classify hemodynamic impairment as either hypo- or hyperperfusion. RESULTS: Overall there was a good agreement of ASL perfusion maps with DSC perfusion imaging on visual analysis. Correlations were found between ASL-BAT/(DSC-)Mean transit time (MTT) (r = .416; P < .01) and ASL-CBF/MTT (r = -.489; P < .01). Using ASL, BAT in ischemic territory was delayed by 55% (P = .001) in patients with hypoperfusion (n = 28); CBF was reduced by 39% (P<.001). All patients with hyperperfusion (n = 6) had higher CBF on ASL. CONCLUSIONS: The use of ASL with multiple TI allows the contrast-free assessment of hemodynamic impairment in ischemic stroke patients. Quantitative ASL perfusion analysis reliably demonstrates areas of delayed BAT and reduced CBF matching findings of DSC.

Multimodal assessment of optokinetic visual stimulation response in migraine with aura.

OBJECTIVE: This study aimed to assess activation patterns and the hemodynamic response to optokinetic stimulation in migraine with aura patients compared with controls. BACKGROUND: It has been proposed that altered visual motion processing in striate and extrastriate visual areas is present in migraine patients and might play a role in the pathophysiology of the disease. Besides activating a large visual network, optokinetic stimulation in particular has been shown to provoke symptoms associated with migraine. METHODS: In this study, we examined the response to visual stimulation in 18 migraine with aura patients compared with 18 healthy controls by using functional magnetic resonance imaging and functional transcranial Doppler, thereby assessing the activation pattern of the visual areas (V1-V5) as well as the vasomotor reactivity of the posterior cerebral artery. For stimulation, we used a vertically rotating optokinetic drum with complex colored figures. RESULTS: Group analysis of migraineurs with aura vs controls revealed different activation patterns in functional magnetic resonance imaging: attenuation of the physiological right lateralization with a significantly increased activation in the left V5 complex, the left area V3, and the right V5 complex. Analysis of the visually evoked flow response of the cerebral blood flow velocity in the posterior cerebral artery showed a larger side-difference of the offset latency (P < .05) and a reduced steepness of the decreasing slope on the left side (P < .05). CONCLUSION: Combining examinations with a good structural (functional magnetic resonance imaging) and temporal (functional transcranial Doppler) resolution is a novel approach to migraine pathophysiology. Our findings of an altered pattern of activation by optokinetic visual stimulation with hyperresponsiveness in visual areas activated by motion perception (V5 and V3) further strengthen the concept of an interictal motion-processing deficit in migraine. This is complemented by the slower restitution of the visually evoked flow response after stimulus offset in migraine with aura patients.

Assessment of intracranial collateral flow by using dynamic arterial spin labeling MRA and transcranial color-coded duplex ultrasound.

BACKGROUND AND PURPOSE: To evaluate the potential of a new dynamic MRA sequence (DynAngio) based on arterial spin labeling for the assessment of intracranial collateral flow. METHODS: Twelve patients with unilateral internal carotid artery obstruction were investigated. Different patterns of collateral flow were compared between DynAngio, transcranial color-coded duplex ultrasound, and time-of-flight MRA. RESULTS: There was a good agreement between the methods, with sensitivities between 80% and 90%. Small collateral vessels were detected more frequently with DynAngio compared to time-of-flight MRA. CONCLUSIONS: DynAngio provides anatomic and similar to transcranial color-coded duplex ultrasound functional information on collateral flow for the assessment of intracranial hemodynamics.

Diffusion and perfusion MRI for the assessment of carotid atherosclerosis.

Atherosclerotic disease of the extracranial vessels is a frequent cause of cerebral ischemia and stroke. Many natural history studies and prospective treatment trials with large patient samples have focused on optimal patient assessment in regard to medical or interventional measures. Clinical decision making nowadays is largely based on the identification, visualization, and grading of the local stenosis, and the identification of neurologic symptoms related to carotid artery stenosis. MRI already has contributed considerably as many surgeons no longer require preoperative conventional contrast angiography but may use the combination of duplex ultrasound studies and MRA for visualization of the pathology. Besides MRA improvements, DWI and PWI are increasingly used in addition to conventional MR contrasts (PD, T2-, T1-weighted MRI) in attempts to gather information on tissue status and the pathophysiology of hemodynamic compromise and cerebral ischemia in patients with carotid artery stenosis. Obtaining background information using this array of MR data may eventually become a basis for optimal risk-benefit assessment in patients with carotid artery stenosis.