Monitoring Stroke Patients With Near-infrared Spectroscopy Before, During and After Endovascular Treatment


The purpose of this study is to examine the hemodynamics of stroke patients with near-infrared spectroscopy before, during and after endovascular treatment and their relations to disabilities and mortality 3 months after treatment.

Full Title of Study: “Near-infrared Spectroscopy in Endovascular Treatment (Danish: Nær-infrarød Spektroskopi Ved endovaskulær Trombektomi)”

Study Type

  • Study Type: Observational
  • Study Design
    • Time Perspective: Prospective
  • Study Primary Completion Date: February 15, 2021

Detailed Description

Endovascular treatment is the revascularization after ischemic stroke due to large-artery occlusion by mechanical removal of thrombi with an intraarterial catheter. The area around the infarction called the penumbra, which has partial blood supply by collateral vessels, can thereby be salvaged and the neuronal function restored. EVT lowers the disabilities and the morbidity if it is performed within 6 hours of onset or within 24 hours in stroke patients with a significant penumbra (Rodrigues, Neves et al. 2016). However, complications can arise during EVT including critically failing CBF, intracranial hemorrhage and embolization of the thrombus to more peripheral vessels, which can all result in further brain damage. To avoid these repercussions or detect them as fast as possible as well as detecting successful interventions, a suitable method for monitoring CBF over time is needed. NIRS is a commonly applied method that examines CBF in the cerebral cortex, which has already been used as intraoperative monitoring during abdominal and cardiac surgery (Yu, Zhang et al. 2018), but only in minor studies of EVT patients, where results have been very promising and associated to long-term outcomes (Hametner, Stanarcevic et al. 2015, Ritzenthaler, Cho et al. 2017). NIRS exploits that absorption of infrared light is only changed by hemoglobin, which can therefore by measured over time. NIRS is a non-invasive and safe method that measures oxygenated and deoxygenated hemoglobin in the cerebral cortex (Ferrari and Quaresima 2012). Cerebral autoregulation (CA) is a complex mechanism that maintains an relatively constant and adequate CBF, which is often impaired in acute stroke patients (Paulson, Strandgaard et al. 1990). The nature of CA can be examined with NIRS (Obrig, Neufang et al. 2000, Reinhard, Wehrle-Wieland et al. 2006, Schytz, Hansson et al. 2010, Zweifel, Dias et al. 2014) and impairment can be shown (Li, Wang et al. 2010, Han, Li et al. 2014, Han, Zhang et al. 2014, Phillip and Schytz 2014). NIRS examinations of CA has never been done during EVT and the relation between changes in CA and patient outcome remains unknown. This leads to the following hypothesis: – CBF and CA can be monitored with NIRS before, during and after EVT and detect complications and successful EVTs. – CBF and CA during and after EVT can be associated to the disabilities and mortality of stroke patients 3 months after the treatment. The investigators will examine stroke patients who receive EVT with NIRS. The equipment will be placed on participants forehead when they arrive to the department and monitored for up to 2 hours after EVT. A 20-minute follow-up NIRS examinations will be done at 24 hours and 3 months after EVT. National Institute of Health Stroke Scale (NIHSS) will be performed before and after EVT, at 24 hours and 3 months after EVT. Participants will be assessed for functioning level and scored for independence with Modified Ranking Scale and screened for new vascular events, complications related to EVT and death by cause after 3 months. To satisfy power calculations, 100 patients will be enrolled in the study.


  • Other: Monitoring with near-infrared spectroscopy
    • No interventions are used. Stroke patients are examined with near-infrared spectroscopy (NIRS). NIRS examinations are done with Octamon system (Artinis Medical Systems, Elst, The Netherlands) consisting of 8 transmitters emitting infrared light of 760 and 850 nm and 2 receivers measuring oxygenated and deoxygenated hemoglobin in the frontal cortex. Examination protocol can be found in detailed description.

Clinical Trial Outcome Measures

Primary Measures

  • Oxygenated hemoglobin ratio of total hemoglobin before, during and after endovascular treatment
    • Time Frame: From onset of examination before EVT, during EVT and up to 2 hours after EVT.
    • Variability in oxygenated hemoglobin from onset of examination before EVT until end of examination up to 2 hours after EVT

Participating in This Clinical Trial

Inclusion Criteria

  • Stroke patients receiving endovascular treatment Exclusion Criteria:

  • Premorbid mRS > 3 – Acute EEG examinations within 2 hours after EVT – Neurosurgical evacuation within 2 hours after EVT – Remaining life expectancy < 90 days

Gender Eligibility: All

Minimum Age: 18 Years

Maximum Age: N/A

Are Healthy Volunteers Accepted: No

Investigator Details

  • Lead Sponsor
    • Helle Klingenberg Iversen
  • Provider of Information About this Clinical Study
    • Sponsor-Investigator: Helle Klingenberg Iversen, Senior neurologist, Head of Stroke Unit, Associate Professor – Rigshospitalet, Denmark
  • Overall Official(s)
    • Helle K Iversen, DMSc, Principal Investigator, Department of Neurology, Rigshospitalet


Hametner C, Stanarcevic P, Stampfl S, Rohde S, Veltkamp R, Bosel J. Noninvasive cerebral oximetry during endovascular therapy for acute ischemic stroke: an observational study. J Cereb Blood Flow Metab. 2015 Nov;35(11):1722-8. doi: 10.1038/jcbfm.2015.181. Epub 2015 Aug 5.

Ritzenthaler T, Cho TH, Mechtouff L, Ong E, Turjman F, Robinson P, Berthezene Y, Nighoghossian N. Cerebral Near-Infrared Spectroscopy: A Potential Approach for Thrombectomy Monitoring. Stroke. 2017 Dec;48(12):3390-3392. doi: 10.1161/STROKEAHA.117.019176. Epub 2017 Oct 31.

Ferrari M, Quaresima V. A brief review on the history of human functional near-infrared spectroscopy (fNIRS) development and fields of application. Neuroimage. 2012 Nov 1;63(2):921-35. doi: 10.1016/j.neuroimage.2012.03.049. Epub 2012 Mar 28.

Paulson OB, Strandgaard S, Edvinsson L. Cerebral autoregulation. Cerebrovasc Brain Metab Rev. 1990 Summer;2(2):161-92.

Obrig H, Neufang M, Wenzel R, Kohl M, Steinbrink J, Einhaupl K, Villringer A. Spontaneous low frequency oscillations of cerebral hemodynamics and metabolism in human adults. Neuroimage. 2000 Dec;12(6):623-39. doi: 10.1006/nimg.2000.0657.

Reinhard M, Wehrle-Wieland E, Grabiak D, Roth M, Guschlbauer B, Timmer J, Weiller C, Hetzel A. Oscillatory cerebral hemodynamics–the macro- vs. microvascular level. J Neurol Sci. 2006 Dec 1;250(1-2):103-9. doi: 10.1016/j.jns.2006.07.011. Epub 2006 Oct 2.

Schytz HW, Hansson A, Phillip D, Selb J, Boas DA, Iversen HK, Ashina M. Spontaneous low-frequency oscillations in cerebral vessels: applications in carotid artery disease and ischemic stroke. J Stroke Cerebrovasc Dis. 2010 Nov-Dec;19(6):465-74. doi: 10.1016/j.jstrokecerebrovasdis.2010.06.001.

Zweifel C, Dias C, Smielewski P, Czosnyka M. Continuous time-domain monitoring of cerebral autoregulation in neurocritical care. Med Eng Phys. 2014 May;36(5):638-45. doi: 10.1016/j.medengphy.2014.03.002. Epub 2014 Apr 1.

Han Q, Li Z, Gao Y, Li W, Xin Q, Tan Q, Zhang M, Zhang Y. Phase synchronization analysis of prefrontal tissue oxyhemoglobin oscillations in elderly subjects with cerebral infarction. Med Phys. 2014 Oct;41(10):102702. doi: 10.1118/1.4896113.

Han Q, Zhang M, Li W, Gao Y, Xin Q, Wang Y, Li Z. Wavelet coherence analysis of prefrontal tissue oxyhaemoglobin signals as measured using near-infrared spectroscopy in elderly subjects with cerebral infarction. Microvasc Res. 2014 Sep;95:108-15. doi: 10.1016/j.mvr.2014.08.001. Epub 2014 Aug 10.

Li Z, Wang Y, Li Y, Wang Y, Li J, Zhang L. Wavelet analysis of cerebral oxygenation signal measured by near infrared spectroscopy in subjects with cerebral infarction. Microvasc Res. 2010 Jul;80(1):142-7. doi: 10.1016/j.mvr.2010.02.004. Epub 2010 Feb 13.

Phillip, D. and H.W. Schytz, Spontaneous Low Frequency Oscillations in Acute Ischemic Stroke ? A Near Infrared Spectroscopy (NIRS) Study. Journal of Neurology & Neurophysiology, 2014. 05(06).

Citations Reporting on Results

Rodrigues FB, Neves JB, Caldeira D, Ferro JM, Ferreira JJ, Costa J. Endovascular treatment versus medical care alone for ischaemic stroke: systematic review and meta-analysis. BMJ. 2016 Apr 18;353:i1754. doi: 10.1136/bmj.i1754.

Yu Y, Zhang K, Zhang L, Zong H, Meng L, Han R. Cerebral near-infrared spectroscopy (NIRS) for perioperative monitoring of brain oxygenation in children and adults. Cochrane Database Syst Rev. 2018 Jan 17;1(1):CD010947. doi: 10.1002/14651858.CD010947.pub2.

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