Intracranial Atheromatous Stenosis

Intracranial atherosclerotic stenosis (ICAS) is one of the most common causes of stroke worldwide (Gorelick et al., Stroke. 39(8):2396–99, 2008), with wide variations in prevalence between ethnic groups. ICAS is reported to be highly prevalent in Asian (De Silva et al., Stroke. 38(9):2592–4, 2007), Black, and Hispanic (Sacco et al., Stroke. 26(1):14–20, 1995), while it remains an uncommon cause of stroke in Caucasian populations (Sacco et al., Stroke. 26(1):14–20, 1995; White et al., Circulation. 111(10):1327–31, 2005). The most common sites of ICAS, in descending order, are the middle cerebral artery, the internal carotid artery distal to the petrous segment, the mid-basilar trunk, the intracranial vertebral (V4 segment) arteries, and the posterior and anterior cerebral arteries (Chimowitz et al., N Engl J Med. 352(13):1305–16, 2005; Chimowitz et al., N Engl J Med. 365(11):993–1003, 2011). Symptomatic (i.e., causing stroke or transient ischemic attack [TIA]) ICAS is associated with a high risk of recurrent cerebrovascular ischemia (Chimowitz et al., N Engl J Med. 352(13):1305–16, 2005; Chimowitz et al., N Engl J Med. 365(11):993–1003, 2011; Zaidat et al., JAMA. 313(12):1240–8, 2015), especially in cases of severe stenosis (more than 70% of the diameter of a major intracranial artery). According to recent trials, recurrence rates can reach as high as 7% in the first year (Kasner et al., Circulation. 113(4):555–63, 2006; Gao et al., JAMA. 328(6):534–42, 2022), even despite aggressive optimal medical treatment (i.e., combination of antiplatelet medication and vascular risk factor control). Alternatives therapies are therefore still needed for these patients. Interventional treatments (percutaneous transluminal angioplasty with or without stenting (PTAS)) exist to attempt rapid restoration of normal arterial caliber and prevent short- and long-term morbidity and mortality. These techniques have been used in hyperacute and subacute settings. However, over the past two decades, randomized trials have generally shown harm and lack of benefit even when combined with the best medical therapy (Chimowitz et al., N Engl J Med. 352(13):1305–16, 2005; Chimowitz et al., N Engl J Med. 365(11):993–1003, 2011; Zaidat et al., JAMA. 313(12):1240–8, 2015; Gao et al., JAMA. 328(6):534–42, 2022).