Cortical Indocyanine Green Videography for Quantification of Acute Hypoperfusion After Subarachnoid Hemorrhage

BACKGROUND: Acute neurological deficits after subarachnoid hemorrhage (SAH) correlate with outcome, and a phase of acute hypoperfusion was characterized recently. Indocyanine green (ICG) videography is an established intraoperative imaging technique with important descriptive potential. OBJECTIVE: To analyze whether ICG can be used to analyze and confirm perfusion changes early after SAH. METHODS: We prospectively enrolled 11 patients with acute SAH within the past 24 hours and 14 patients undergoing surgery for unruptured aneurysms. Cortical ICG videography was performed, and offline analysis included the arterial, parenchymal, and venous cortical compartment. Transit times, signal gradient, maximum of fluorescence intensity, and the area under the curve were calculated as surrogate markers for perfusion characteristics. RESULTS: Arterial, parenchymal, and venous transit times were comparable in both groups. The velocity of signal change in SAH patients was significantly lower in all 3 compartments (P < .001, P < .01, P < .001, respectively), as was the peak fluorescence intensity (P < .001). In SAH patients, fluorescence intensity did not vary between areas with and without diffuse cortical blood. Area under the curve analysis showed significantly lower values in SAH patients compared with the control group (P < .001). CONCLUSION: Cortical ICG videography and analysis are feasible during surgery. Patients early after SAH have a significantly lower velocity of signal change, lower peak of fluorescence intensity, and lower overall area under the curve, but similar transit times. This technique can be used to quantify perfusion alteration, in this case, acute SAH, and may be used as an adapted measurement tool for intraoperative therapy. ABBREVIATIONS: AImax, peak fluorescence intensity AUC, area under the curve CBF, cerebral blood flow CBV, cerebral blood volume HH, Hunt and Hess ICG, indocyanine green ICP, intracranial pressure MAP, mean arterial pressure mFS, modified Fisher Scale MTT, mean transit time ROI, region of interest TTP, time to peak