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Background and purposeIndirect cerebral revascularization has been successfully used for treatment in Moyamoya disease and symptomatic intracranial atherosclerosis. While angiographic neovascularization has been demonstrated after surgery, measurements of local tissue perfusion are scarce and may not reflect the reported successful clinical outcomes. We investigated probabilistic independent component analysis and conventional perfusion parameters from DSC-MR imaging to measure postsurgical changes in tissue perfusion.Materials and methodsIn this prospective study, 13 patients underwent unilateral indirect cerebral revascularization and DSC-MR imaging before and after surgery. Conventional perfusion parameters (relative cerebral blood volume, relative cerebral blood flow, and TTP) and probabilistic independent components that reflect the relative contributions of DSC signals consistent with arterial, capillary, and venous hemodynamics were calculated and examined for significant changes after surgery. Results were compared with postsurgical DSA studies to determine whether changes in tissue perfusion were due to postsurgical neovascularization.ResultsBefore surgery, tissue within the affected hemisphere demonstrated a high probability for hemodynamics consistent with venous flow and a low probability for hemodynamics consistent with arterial flow, whereas the contralateral control hemisphere demonstrated the reverse. Consistent with symptomatic improvement, the probability for venous hemodynamics within the affected hemisphere decreased with time after surgery (P = .002). No other perfusion parameters demonstrated this association. Postsurgical DSA revealed an association between an increased preoperative venous probability in the symptomatic hemisphere and neovascularization after surgery.ConclusionsProbabilistic independent component analysis yielded sensitive measurements of changes in local tissue perfusion that may be associated with newly formed vasculature after indirect cerebral revascularization surgery.

Copyright © 2014 by the Congress of Neurological Surgeons. BACKGROUND: Remote ischemic conditioning (RIC) is a powerful endogenous mechanism whereby a sublethal ischemic stimulus confers a protective benefit against a subsequent severe ischemic insult. RIC has significant potential clinical implications for the prevention of delayed ischemic neurological deficit after aneurysmal subarachnoid hemorrhage (aSAH). Although RIC has been extensively investigated in animal models, it has not been fully evaluated in humans. OBJECTIVE: To assess the feasibility and safety of RIC for aSAH in a phase I clinical trial. METHODS: Consecutive patients hospitalized for treatment of an aSAH who met the inclusion/exclusion criteria were approached for consent. Enrolled patients received up to 4 RIC sessions on nonconsecutive days. Primary end points were the development of a symptomatic deep venous thrombosis, bruising, or injury to the limb and request to stop by the patient or surrogate. The secondary end points were the development of new neurological deficits or cerebral infarct, demonstrated by brain imaging after enrollment, and neurological deficit and condition at follow-up. RESULTS: Twenty patients were enrolled and underwent 76 RIC sessions, 75 of which were completed successfully. One session was discontinued when the patient became confused. No patient developed a deep venous thrombosis or injury to the preconditioned limb. No patient developed delayed ischemic neurological deficit during enrollment. At follow-up, median modified Rankin Scale score was 1 and Glasgow Outcome Scale score was 5. CONCLUSION: The RIC procedure was well tolerated and did not cause any injury. RIC for aSAH warrants investigation in a subsequent pivotal clinical trial.