Intracranial arterial stenoses: current viewpoints, novel approaches, and surgical perspectives

Abstract

Ten percent of all strokes occurring in the USA are caused by intracranial arterial stenosis (IAS). Symptomatic IAS carries one of the highest rates of recurrent stroke despite intensive medical therapy (25 % in high-risk groups). Clinical results for endovascular angioplasty and stenting have been disappointing. The objectives of this study were to review the contemporary understanding of symptomatic IAS and present potential alternative treatments to resolve factors not addressed by current therapies. We performed a literature review on IAS pathophysiology, natural history, and current treatment. We present an evaluation of the currently deficient aspects in its treatment and explore the role of alternative surgical approaches. There is a well-documented interrelation between hemodynamic and embolic factors in cerebral ischemia caused by IAS. Despite the effectiveness of medical therapy, hemodynamic factors are not addressed satisfactorily by medications alone. Collateral circulation and severity of stenosis are the strongest predictors of risk for stroke and death. Indirect revascularization techniques, such as encephaloduroarteriosynangiosis, offer an alternative treatment to enhance collateral circulation while minimizing risk of hemorrhage associated with hyperemia and endovascular manipulation, with promising results in preliminary studies on chronic cerebrovascular occlusive disease. Despite improvements in medical management for IAS, relevant aspects of its pathophysiology are not resolved by medical treatment alone, such as poor collateral circulation. Surgical indirect revascularization can improve collateral circulation and play a role in the treatment of this condition. Further formal evaluation of indirect revascularization for IAS is a logical and worthy step in the development of intracranial atherosclerosis treatment strategies.

Association between serum cystatin C levels and the severity or potential risk factors of acute ischemic stroke

“…Intracranial arterial stenosis affects cerebral blood flow, may increase the risk of recurrent stroke, and is highly prevalent in Asia. 39,40 Here, we did not find any correlation between serum cystatin C levels and intracranial arterial stenosis. As mentioned previously, Cystatin C levels and cerebral microbleeds have been shown to be closely associated.…”

Encephaloduroarteriosynangiosis for adult intracranial arterial steno-occlusive disease: long-term single-center experience with 107 operations

“…On one hand, the process of neovascularization from arteries of the external carotid circulation, the formation of spontaneous connec- tions to the intracranial vessels, and their maturation into vessels capable of supporting the cerebral circulation offer unprecedented opportunities to understand mechanisms of angiogenesis and arteriogenesis and their potential role as therapeutic tools. 9 On the other hand, only if this process can protect individuals at risk from stroke early enough and in the long term with stable mature collaterals should EDAS be considered a viable alternative to other strategies of treatment. Although no pivotal clinical trials have been performed in the setting of adults with MMD, various forms of indirect revascularization, including EDAS, have been used in the treatment of MMD for decades.…”

Evaluation of Encephaloduroarteriosynangiosis Efficacy Using Probabilistic Independent Component Analysis Applied to Dynamic Susceptibility Contrast Perfusion MRI

“…5,7 In brief, the superficial temporal artery (STA) is identified and dissected with its surrounding galeal cuff. A craniotomy is performed, and the dura is opened in cruciate fashion, preserving middle meningeal artery branches.…”

“…This results in the sprouting of new vessels that gradually form new anastomoses with the intracranial circulation, improving perfusion and reducing the risk of stroke. 7 In a recently published report on treatment outcomes with EDAS, the rate of stroke was 2.4% (5.6% in patients with ICAS, 0% in patients with MMD) within two years after surgery. 9 These rates are lower than the previously observed rates for medical treatment (15%) or angioplasty and stenting (21%) in the SAMMPRIS trial.…”