Introduction
Endovascular thrombectomy (EVT) has become standard of care for anterior circulation stroke in patients with large vessel occlusion irrespective of stroke lateralization. Strokes affecting the left and right hemisphere, however, are different with regards to acute clinical symptoms and outcome. Lateralization of specific cortical functions, e.g., language or spatial perception, results in important clinical differences between the hemispheres. In line with this, previous studies have demonstrated that patients with right hemispheric stroke (RHS) are less frequently recognized as having a stroke, present later to hospital, are less likely to receive intravenous thrombolysis therapy (IVT) and show a worse functional recovery compared to patients suffering from left hemispheric stroke (LHS)
[1‐
3].
Moreover, imaging studies revealed that RHS may comprise a substantial and similar infarct size compared to LHS, while having a lower National Institutes of health Stroke Scale Score (NIHSS), thus, indicating that the NIHSS is biased towards LHS and presumably underpowered for assessing the clinical severity of RHS adequately
[4‐
6].
However, studies on functional outcome, commonly assessed by the modified Rankin Scale (mRS), comparing RHS and LHS have provided conflicting evidence so far
[7‐
9]. To our knowledge, the impact of hemispheric lateralization on quality of life in stroke patients after EVT has not yet been adequately addressed.
Thus, the objective of our study was to determine whether (a) outcome of stroke patients after EVT, assessed by the modified Rankin Scale (mRS) and self-reported HRQoL, differ between LHS and RHS patients and (b) stroke laterality has an influence on these outcome parameters after EVT in a large, representative, multi-center patient cohort of clinical practice.
Discussion
In the present study, which included stroke thrombectomy patients from a large, prospective, multi-center and industry-independent registry, we provide real world data on the impact of stroke laterality on functional outcome and HRQoL, and detailed information about different health dimensions after EVT in patients with LHS compared to RHS.
In this study cohort of clinical practice, we found an effect of hemispheric lateralization on functional outcome assessed by mRS. In addition, we observed a highly significant effect of stroke laterality on HRQoL.
Most of the trials on stroke and thrombectomy assessed functional outcome by the mRS which mainly reflects the physical disability of a patient. Previous studies already demonstrated that the impact of stroke laterality on functional outcome after stroke and thrombectomy is still inconclusive [
7‐
9]. In line with this, the association of hemispheric lateralization only showed a ß coefficient of − 0.109 (CI 95% − 0.217–0.000; p = 0.049) in our patient cohort.
However, previous studies on stroke and thrombectomy have suggested to assess outcome and effectiveness of medical treatment by additional scales beside the mRS, such as patient self-reported outcomes. In particular, HRQoL is a valuable complementary outcome measure to evaluate outcome after stroke and EVT, as already applied and stated by several studies [
12,
14,
15]. The European Stroke Organization has also prioritized the use of patient-reported outcomes in research studies to develop specific targets in stroke rehabilitation and facilitate the recovery process [
16].
One possible explanation for the better HRQoL in LHS patients is that recovery might be protracted in RHS patients due to non-dominant hemisphere symptoms such as depression, apathy and amotivation [
3,
7]. Furthermore, LHS patients tend to remain longer in rehabilitation [
17] which may also account for the better HRQoL in this subgroup of patients. A lower rehabilitation potential of RHS patients due to neglect has also been discussed [
18,
19].
In fact, in our study population RHS patients more frequently suffered from pain/discomfort and anxiety/depression, and perceived higher mobility constraints than LHS patients at 90 days. Thus, RHS patients might be scored well on available functional assessment scores while still being extremely disabled by these factors. Thus, our findings provide valuable additional data for targeted rehabilitation therapies after EVT, in particular for patients with RHS. In consequence, our results suggest that patients with RHS should be actively assessed and treated for pain, anxiety and depression beside physical disability after EVT to improve their quality of life.
In line with our results, a previous study found a significant association of depression with stroke lesions of the right hemisphere [
3]. Furthermore, since in LHS patients speech disabilities are in the foreground, they might perceive mobility impairments less than RHS subjects. Moreover, patients with RHS suffer more frequently from the pusher-syndrome (lateropulsion) after stroke [
20] which might also account for a worse perception of mobility. Interestingly, imaging studies revealed an increased activation of the right-sided insula in the presence of neuropathic pain [
21,
22], indicating a strong association of right hemispheric lesions with the perception of pain, consistent with our findings.
In between-group comparisons, we discovered a higher baseline NIHSS in LHS patients compared to RHS patients. Thus, we confirmed previous findings, as several studies found similar results after stroke and thrombectomy [
7‐
9,
23]. The difference in the NIHSS between the hemispheres might be explained by a structural inherent bias of the NIHSS itself. In particular, the NIHSS is biased towards LHS, as the NIHSS gives more weight to language, attributable to left hemispheric lesions, than to hemispatial neglect, a hallmark of RHS [
6].
Notably, patients with RHS were shown to have a comparable infarct volume as LHS [
4] despite scoring less on the NIHSS. This indicates that the NIHSS systematically underestimates stroke severity in RHS patients [
4]. The different weighting in scoring the NIHSS for both hemispheres may impact on treatment decision that rely on NIHSS tresholds. In fact, RHS patients were shown to receive less frequently IVT than LHS subjects [
7]. It was suggested that a combination of late diagnosis, delayed admission to hospital and the use of stroke severity scales biased towards the left hemisphere may have induced this imbalance of treatment [
18,
19]. However, we did not find different IVT rates between the hemispheres in our patient cohort of clinical practice.
The differences in clinical symptoms depending on the side of lesion may, indeed, affect awareness and recognition of stroke. Since sudden speech disturbances are more apparent than perceptual deficits, RHS patients are more likely to be later diagnosed as a stroke, and, in consequence, present later to hospital [
1]. This is in line with our findings showing longer workflow times in RHS patients of our study cohort. Interestingly, the ASPECT score was found to be lower in RHS patients, potentially explained by the deferred admission [
1]. Correspondingly, the higher rate of any ICH 24 h after intervention in RHS patients might be attributed to the higher extent of early ischemic changes on brain imaging in RHS patients on admission.
There are some factors that may limit our findings. Our study provides a short-term follow up period of three months after stroke thrombectomy for HRQoL measurements. Long-term assessments may provide additional clues about HRQoL. Furthermore, in cases who lacked capability the questionnaire was completed by proxies. This might reduce the validity of the responses, since over- or underestimation of QoL might occur. However, we believe that this limitation did not significantly confound our findings, since agreement between caregivers and patient self-reports have been demonstrated to be reasonable [
24].
Acknowledgements
GSR-ET Steering Committee Investigators: Universitätsklinikum Hamburg-Eppendorf: Prof. Dr. C. Gerloff, Prof. Dr. J. Fiehler, Prof. Dr. G. Thomalla, Dr. med. A. Alegiani; Klinikum rechts der Isar: Dr. Boeckh-Behrens, Dr. Silke Wunderlich; Universitätsklinik Tübingen: Prof. Dr. Ulrike Ernemann, Dr. Sven Poli; Charité–Campus Benjamin Franklin und Campus Charité Mitte, Berlin: Dr. Eberhard Siebert, Prof. Dr. Christian H. Nolte; Charité—Campus Virchow Klinikum, Berlin: Dr. Sarah Zweynert, Dr. Georg Bohner; Sana Klinikum Offenbach: Dr. med. Alexander Ludolph, Dr. med. Karl-Heinz Henn; Uniklinik Frankfurt/ Main: Dr. med. Jan Hendrik Schäfer, Dr. Fee Keil; Asklepios Klinik Altona: Prof. Dr. Joachim Röther, Prof. Dr. Bernd Eckert; Klinikum Altenburger Land: Prof. Dr. Jörg Berrouschot, Dr. Albrecht Bormann; Uniklinik Bonn: Dr. med. Franziska Dorn, Prof. Dr. Gabor Petzold; Klinikum Lüneburg: Dr. Christoffer Kraemer, Dr. med Hannes Leischner; Uniklinik München (LMU): Dr. med. Christoph Trumm, Dr. Dr. Steffen Tiedt, Dr. Lars Kellert; Klinikum Osnabrück: Dr. Martina Petersen, Prof. Dr. Florian Stögbauer; Bezirkskrankenhaus Günzburg: Dr. med. Michael Braun, Prof. Dr. Gerhard F. Hamann; Universitätsmedizin Mainz: Prof. Dr. Klaus Gröschel, Dr. Timo Uphaus; Uniklinik RWTH Aachen: Dr. med. Arno Reich, Prof. Dr. med. Omid Nikoubashman; Johannes Wesling Klinikum Minden: Prof. Dr. med. Peter Schellinger, Prof. Dr. med. Jan Borggrefe; Klinikum Nordstadt: Dr. med. Jörg Hattingen; Universitätsmedizin Göttingen: Prof. Dr. med. Jan Liman, Dr. med. Marielle Ernst.
Declarations
Competing interests
CB: The author declares that he has no competing interest. FF: received personal fees from Eppdata GmbH outside the submitted work. LM: received compensation as a speaker for Balt Prime outside the submitted work. MDC has received research grants from the Werner Otto Stiftung outside the submitted work. JF receives research support from the German Ministry of Science and Education (BMBF), German Ministry of Economy and Innovation (BMWi), German Research Foundation (DFG), European Union (EU), Hamburgische Investitions- und Förderbank (IFB), Medtronic, Microvention, Stryker; and serves as a consultant for Acandis, Cerenovus, Medtronic, Microvention, Penumbra, Phenox, and Stryker. CG serves on scientific advisory boards for Bayer Vital, Boehringer Ingelheim, Acticor Biotech, Amgen, and Prediction Biosciences; has received funding for travel and/or speaker/ consulting honoraria from Bayer Vital, Boehringer Ingelheim, Sanofi Aventis, Amgen, EBS Technologies, GlaxoSmithKline, Lundbeck, Pfizer, Silk Road Medical, and UCB, and Abbott; serves on editorial boards for INFO Neurologie & Psychiatrie and Aktuelle Neurologie and as editor of textbook Therapie und Verlauf neurologischer Erkrankungen; has received grants to supporting employees/ scientists of his clinic from Merz Pharmaceuticals, Allergan, Novartis, and NeuroConn; and receives research support from Deutsche Forschungsgesellschaft, the European Union, Wegener Foundation, Schilling Foundation, and Werner-Otto- Foundation. GT has received personal fees as consultant or lecturer from Acandis, Bayer, Boehringer Ingelheim, Bristol-Myers Squibb/Pfizer, Daichi Sankyo, Stryker, and research grants from Bayer, Federal Ministry for Economic Affairs and Energy (BMWi), Corona-Foundation, German Research Foundation (DFG), Else Kröner-Fresenius Foundation, European Union (Horizon 2020), German Innovation Fund.
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