Optical imaging of motor cortical activation using functional near-infrared spectroscopy

This paper describes a study from a poster presentation. It discusses optical imaging of motor cortical activation using functional near-infrared spectroscopy

Detection of cerebral ischemia in neurovascular surgery using quantitative frequency-domain near-infrared spectroscopy.

ObjectThere is great value in monitoring for signs of ischemia during neurovascular procedures. Current intraoperative monitoring techniques provide real-time feedback with limited accuracy. Quantitative frequency-domain near-infrared spectroscopy (Q-NIRS) allows measurement of tissue oxyhemoglobin (HbO2), deoxyhemoglobin (HHb), and total hemoglobin (tHb) concentrations and brain tissue oxygen saturation (SO2), which could be useful when monitoring for evidence of intraoperative ischemia.MethodsUsing Q-NIRS, the authors monitored 25 neurovascular procedures including aneurysm clip placement, arteriovenous malformation resection, carotid endarterectomy, superficial temporal artery-middle cerebral artery (MCA) bypass surgery, external carotid artery-MCA bypass surgery, encephaloduromyosynangiosis, and balloon occlusion testing. The Q-NIRS technology provides measurable cerebral oxygenation values independent from those of the scalp tissue. Thus, alterations in the variables measured with Q-NIRS quantitatively reflect cerebral tissue perfusion. Bilateral monitoring was performed in all cases. Five of the patients exhibited evidence of clinical ischemic events during the procedures. One patient suffered blood loss with systemic hypotension and developed diffuse brain edema intraoperatively, one patient suffered an ischemic event intraoperatively and developed an occipital stroke postoperatively, and one patient showed slowing on electroencephalography intraoperatively during carotid clamping; in two patients balloon occlusion testing failed. In all cases of ischemic events occurring during the procedure, Q-NIRS monitoring showed a decrease in HbO2, tHb, and SO2, and an increase in HHb.Conclusions. Quantitative frequency-domain near-infrared spectroscopy provides quantifiable and continuous real-time information about brain oxygenation and hemodynamics in a noninvasive manner. This continuous intraoperative oxygenation monitoring is a promising method for detecting ischemic events during neurovascular procedures

Abstract W P21: Extent of Reperfusion and Clinical Outcomes After Endovascular Therapy: More is Better

Background: Revascularization is critical to the treatment of acute stroke, yet the association between degree of reperfusion and clinical outcome of endovascular therapy has been incompletely characterized. Methods: In a prospectively maintained registry, we analyzed acute ischemic stroke patients treated with endovascular therapy from 2004-2013. Final TICI scores were compared to non-disabled (mRS 0-2), independent (mRS 0-3), and poor (mRS 5-6) outcomes at discharge in a univariate analysis. Multiple regression analysis was performed to separate effects of baseline patient characteristics, stroke severity, complications, and technical aspects of endovascular treatment. To determine the maximal predictive value of the TICI score, the ROC curve for binned combinations of TICI were compared. Results: Of 183 patients, age was mean 68.4 ± 16.9 years, 58% were female, baseline NIHSS was 16.5 ± 6.9, and mean time from stroke onset to groin puncture was 395 ± 378 minutes. At discharge, the rate of freedom from disability (mRS 0-2) was 15%, freedom from dependency (mRS 0-3) 26%, and poor outcome (mRS 5-6) 54%. Any reperfusion (TICI 2a or higher) was achieved in 79% of patients. Substantial reperfusion (TICI 2b or higher) was associated with higher rates of non-disabled (26% vs 4%, p &lt; 0.001) and independent outcome (37% vs 15%, p = 0.001), and reduced poor outcome (42% vs 66%, p = 0.001). In the multivariate analysis, independent predictors of non-disabled outcome included higher TICI (unmodified 5-level score, β = -0.260, p &lt; 0.001), younger age (β = 0.289, p &lt; 0.001), and lower initial NIHSS (β = 0.355, p &lt; 0.001). Trichotomized TICI scores (0-1, 2a, 2b-3) showed substantial power in predicting discharge outcome: mRS 0-2, c-statistic = 0.72; mRS 0-3, c = 0.64; and mRS 5-6, c = 0.64. Conclusions: Clinical outcome is closely related to the degree of reperfusion achieved during endovascular stroke intervention. Age and initial stroke severity additionally help differentiate patients who are more likely to do well from those who will not. Trichotomized TICI scores are highly predictive of functional clinical outcome. </jats:p

Abstract T P29: Arterial-Spin Labeled MRI After Endovascular Stroke Therapy: Validation of a Novel Scale to Quantify the Degree and Heterogeneity of Reperfusion

Background: The degree of reperfusion in acute stroke is a key predictor of clinical outcome, yet validation of a noninvasive imaging technique such as arterial spin-labeled MRI (ASL) that can quantify both hypo- and hyperperfusion is needed. Methods: Consecutive series of endovascular therapy for acute stroke and ASL-MRI within 36 hours after treatment start during a 3-year period were analyzed. Reperfusion on DSA was scored with TICI and mTICI (2b definitions of 2/3 and ½, respectively). ASL cerebral blood flow was graded with a scale analogous to mTICI (0=none, 1=&lt; ½, 2=&gt;½, 3=complete) separately for hypo- and hyperperfusion based on occlusion site, yet blinded to TICI/mTICI results. Results: 64 patients (mean age 67.7 ± 13.9 years; 53% women; median baseline NIHSS 15 (2-38)) had ASL acquired within 36 hours (median 7.07 hours (2.69-33.08)) from start of IV thrombolysis or thrombectomy over a 3-year period. 31/64 (48%) patients received IV tPA before endovascular therapy. DSA revealed 32 M1, 18 ICA, 10 M2, and 4 basilar occlusions. After endovascular treatment, TICI0/mTICI0 (6%), TICI1/mTICI1 (2%), TICI2a/mTICI2a (30%), TICI2a/mTICI2b (22%), TICI2b/mTICI2b (39%) and TICI3/mTICI3 (2%) results were noted. ASL revealed hypoperfusion (0 (19%); 1 (59%); 2 (14%); 3 (8%)) and hyperperfusion (0 (69%); 1 (27%); 3 (5%)). 7 combined patterns of hypo- and hyperperfusion were noted on ASL, all unrelated to baseline clinical variables. ASL mTICI hypoperfusion strongly correlated with DSA mTICI (R=-0.77, p&lt;0.001) and TICI (R=-0.71, p&lt;0.001). ASL hyperperfusion was noted only with TICI2a/mTICI2a (9%), TICI2a/mTICI2b (14%), TICI2b/mTICI2b (9%) and was more common with increased time from DSA to ASL (p=0.017). Conclusions: ASL hypoperfusion within 36 hours of acute stroke therapy strongly correlates with reperfusion scores on DSA, providing a novel means to accurately quantify degree of reperfusion. ASL hyperperfusion, concomitant with hypoperfusion, affects a substantial number of cases, predominantly affecting the TICI2a/mTICI2b reperfusion category on DSA. </jats:p