Turan TN, Chimowitz MI. . 10 questions about intracranial atherosclerosis.The Neurologist. 16:6 400-405 1020.
1. MRA and TCD have high negative predictive values but low positive predictive values for detecting intracranial stenosis. (86-91. v. 36-59 % respectively). They are therefore adequate screening tests but need CTA for diagnosis or catheter angiography. CTA studies have limited statistical power therefore catheter studies are the "gold standard" to determine the degree of stenosis, but also confer risk. A single preliminary study showed CTA had a sensitivity and specificity to detect intracranial stenosis greater than 50 % of of 97.1 and 99.5 % respectively. In ACAS the risk of stroke with catheter angiography was 1.2 %. The SONIA study was the study that helped evaluate the above.
2. The risk of stroke with intracranial stenosis is the highest of any stroke subtype, with respect to symptomatic stenosis of greater than 50 %. The risk of ischemic stroke in any territory within two years was 20 % in aspirin arm and 17 % in the warfarin arm (WASID). Over 70 % of strokes occurred in the same territory. Thus the risk in the symptomatic artery was 15/13 % in aspirin and warfarin arms respectively. This is higher than the risk with atrial fibrillation or cardioembolic stroke.
3. The risk of stroke was proportional to the severity of stenosis (risk of stroke within the symptomatic artery occurred in 6/18 % of patients, respectively, with < 70 and >70 % stenosis.
4. Other risk factors for stroke in the territory included recent symptoms, female gender, and baseline NIHSS >1. Vertebrobasilar arterial disease was NOT a risk factor.
5. Asymptomatic stenosis was very low risk, with a one year risk of stroke of 0 % in one study and 3.5 % in WASID by MRA.
6. "Antithrombotic failures" ie patients already on antiplatelet drugs at time of their stroke, were not at higher risk for recurrent stroke than patients who were not on antiplatelet drugs at the time of their qualifying event.
7. Most important risk factors for recurrent stroke were dyslipidemia and hypertension (SBP> 140).
8. SSYLVIA (stenting of symptomatic atherosclerotic lesions in the vertebral or intracranial arteries) was a ph I study of a bare metal stent that showed technical success and a 10.9 % stroke rate in one year with all strokes within the same artery.
9. SSAMPRIS study is ongoing (Stenting and Aggressive Medical Management of for Prevention of Recurrent Stroke in Intracranial Stenosis) NIH sponsored study. In 764 patients it compares angioplasty and stenting plus aggressive medical management v. medical management alone in patients with 70-99 % stenosis. Patients must have a TIA or nondisabling stroke within 30 days in an appropriate artery to be eligible. The protocol includes ASPIRIN for duration, plavix for first 90 days, aggressive bp and lipid management.
10. See http://www.ssampris.org/ or http://www.sammpris.org/.
1. MRA and TCD have high negative predictive values but low positive predictive values for detecting intracranial stenosis. (86-91. v. 36-59 % respectively). They are therefore adequate screening tests but need CTA for diagnosis or catheter angiography. CTA studies have limited statistical power therefore catheter studies are the "gold standard" to determine the degree of stenosis, but also confer risk. A single preliminary study showed CTA had a sensitivity and specificity to detect intracranial stenosis greater than 50 % of of 97.1 and 99.5 % respectively. In ACAS the risk of stroke with catheter angiography was 1.2 %. The SONIA study was the study that helped evaluate the above.
2. The risk of stroke with intracranial stenosis is the highest of any stroke subtype, with respect to symptomatic stenosis of greater than 50 %. The risk of ischemic stroke in any territory within two years was 20 % in aspirin arm and 17 % in the warfarin arm (WASID). Over 70 % of strokes occurred in the same territory. Thus the risk in the symptomatic artery was 15/13 % in aspirin and warfarin arms respectively. This is higher than the risk with atrial fibrillation or cardioembolic stroke.
3. The risk of stroke was proportional to the severity of stenosis (risk of stroke within the symptomatic artery occurred in 6/18 % of patients, respectively, with < 70 and >70 % stenosis.
4. Other risk factors for stroke in the territory included recent symptoms, female gender, and baseline NIHSS >1. Vertebrobasilar arterial disease was NOT a risk factor.
5. Asymptomatic stenosis was very low risk, with a one year risk of stroke of 0 % in one study and 3.5 % in WASID by MRA.
6. "Antithrombotic failures" ie patients already on antiplatelet drugs at time of their stroke, were not at higher risk for recurrent stroke than patients who were not on antiplatelet drugs at the time of their qualifying event.
7. Most important risk factors for recurrent stroke were dyslipidemia and hypertension (SBP> 140).
8. SSYLVIA (stenting of symptomatic atherosclerotic lesions in the vertebral or intracranial arteries) was a ph I study of a bare metal stent that showed technical success and a 10.9 % stroke rate in one year with all strokes within the same artery.
9. SSAMPRIS study is ongoing (Stenting and Aggressive Medical Management of for Prevention of Recurrent Stroke in Intracranial Stenosis) NIH sponsored study. In 764 patients it compares angioplasty and stenting plus aggressive medical management v. medical management alone in patients with 70-99 % stenosis. Patients must have a TIA or nondisabling stroke within 30 days in an appropriate artery to be eligible. The protocol includes ASPIRIN for duration, plavix for first 90 days, aggressive bp and lipid management.
10. See http://www.ssampris.org/ or http://www.sammpris.org/.
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