1.Diagnosis method
Diagnosis is confirmed based on clinical manifestations and auxiliary examinations.
Non-invasive examination: ultrasound and magnetic resonance angiography (MRA).
Invasive examination: cerebral angiography.
(1) Ultrasound examination of cerebral blood supply arteries
Combined B-mode ultrasonography and transcranial Doppler is the most widely used non-invasive method to detect stenosis of the blood supplying arteries to the brain.
(2) CT angiography (CTA)
It is mainly to understand the presence of stenosis and calcified plaque in the extracranial segment of the carotid artery system, as well as its degree and extent. CTA can be performed as a supplement if the ultrasound method is not certain. CTA can accurately display the diameter of the vessel lumen, if needed, with cine display at a window width of 850 HU and a window position of 200 HU. CTA has advantages over MRA for preoperative and postoperative comparative studies of intracarotid stenting.
(3) Magnetic resonance angiography
(1) MRA: No contrast agent is needed, and vascular imaging can be performed mainly by the mobility of blood, which is a non-invasive examination method. And the observation range is significantly larger than CTA, which can be from the aortic arch to the intracranial cerebral vessels.
②Enhanced MRI scan: The enhanced MRA method is significantly better than conventional MRA, which is faster and has higher definition. Its imaging quality is already very close to that of angiography.
(4) Cerebral angiography
① Cerebral angiography is the ‘gold standard’ for evaluating cerebral blood vessels, but it is an invasive test and not the preferred test method. When stenosis (especially intracranial cerebrovascular stenosis) is suspected by ultrasound, CTA, TCD and MRA, catheter angiography is necessary for a definite diagnosis. This type of examination allows dynamic
②Comprehensive observation of cerebrovascular blood flow, variation, side branch compensation and the integrity of Willis rings.
2.Indications and contraindications.
(1) Indications include: patients with cerebrovascular stenosis that cannot be identified by noninvasive examination but is highly suspected clinically; patients who want to undergo interventional treatment.
(2) Contraindications: There are no absolute contraindications to this test, but caution should be exercised in patients with severe bleeding tendency, patients with iodine allergy, and patients with severe cardiac and pulmonary insufficiency who cannot lie down.
3.Diagnostic process
Clinical stenosis of cerebral blood supply arteries (Titan stenosis)
(1) Non-symptomatic stenosis
(2) Symptomatic stenosis (ICA, CA stenosis > 70%, MCA, BA stenosis > 50%)
Type I stenosis: ischemia in the blood supply region of the stenotic vessel, with clinical manifestations of ischemia in the relevant region
Type II stenosis: ischemia (blood theft) in the region of the blood supply of the collateral vessels caused by the stenosis, with compensation of the blood supply area of the stenotic vessels and the appearance of the blood theft syndrome
Type III stenosis: mixed type.
Each type is subdivided into three subtypes A, B and C, namely
Type A: no infarction in the corresponding area, or luminal infarction without sequelae of neurological deficit, abnormal acetazolamide (Diamox) provocation test, and the patient is expected to benefit after revascularization.
Type B: Small infarct in the corresponding area or combined with tandem stenosis of the distal vessels or occlusion of the distal trunk, but the artery is still involved in the collateral blood supply of other stenosed vessels, and partial benefit is expected after revascularization.
Type C: Large infarction in the corresponding area with major stroke sequelae or chronic occlusion of the distal trunk, and the artery is not involved in the collateral blood supply of other stenoses, and the patient is not expected to benefit after revascularization.
4. Calculation of the degree of stenosis
There are three commonly used methods for measuring the stenosis rate of ICA, namely the NASCET method, the ECST method, and the CC method.
The NASCET method is the most widely used and can be applied to the vertebrobasilar artery and intracranial ICA-MCA systems in addition to the ICA. The formula is: stenosis rate = (normal diameter distal to the stenosis – narrowest diameter of the stenotic segment) / normal diameter distal to the stenosis × 100%.
The formula for the ECST method is: stenosis rate = (estimated normal diameter of the stenotic segment – narrowest diameter of the stenotic segment) / estimated normal diameter of the stenotic segment × 100%.
The formula for the CC method is: stenosis rate = (diameter of common carotid artery – diameter of stenotic segment)/diameter of common carotid artery × 100%.
5.Treatment strategy
(1) Intervention of risk factors for cerebral blood supply artery lesions.
(1) After a comprehensive assessment of the etiology of TIA, the treatment of hypertension should be aimed at a systolic blood pressure below 140 mmHg and a diastolic blood pressure below 90 mmHg. For patients with diabetes, a blood pressure <130/85 mmHg is recommended.
②Smoking should be stopped. Counseling (counseling), nicotine replacement therapy, butalbital, and formal smoking cessation programs are helpful.
Coronary artery disease, arrhythmias, congestive heart failure and heart valve disease should be treated appropriately.
④ Excessive alcohol intake should be prohibited and a formal alcohol cessation program is recommended. Light to moderate alcohol intake (1-2 drinks) may reduce the incidence of stroke.
⑤ Treatment of hyperlipidemia is recommended. Limit the amount of cholesterol in the diet; reduce saturated fatty acids and increase polyunsaturated fatty acids; increase mixed carbohydrates in the diet as appropriate; reduce total calories, maintain an ideal body weight, and engage in regular physical activity. If lipid levels are maintained at high levels (e.g. LDL >130 mg/dl), lipid-lowering medications, especially statins, are recommended. The goal of treatment should be to achieve LDL <100mg/dl.
(6) It is recommended that the blood glucose level in the fasted state is less than 126mg/dl. diabetic patients should use diet control, oral hypoglycemic drugs and insulin to lower blood glucose.
(7) Physical exercise is recommended (30-60 minutes each time, ≥3-4 times per week).
(2) Pharmacological treatment of cerebral blood supply artery stenosis
Recommendation: Patients with stenosis of the cerebral blood supply artery who have TIA or cerebral infarction can be treated according to the relevant chapter.
(3) Surgical treatment
①Carotid endarterectomy (CEA)
Patients with recent cerebral ischemic attack and 70-90% stenosis should be considered for carotid endarterectomy (CEA) if they have good surgical conditions and have had at least one TIA or ischemic stroke within 2 years, regardless of their response to antiplatelet drugs (Class A recommendation). Patients with recent ischemic episodes and 50-60% stenosis should be considered for clinical factors affecting the likelihood of stroke and surgical risk. Patients with arterial stenosis <50% with recent ischemic attack have less benefit from carotid endarterectomy (Class A recommendation), and antiplatelet and other medications are recommended for these patients.
② Endostenting of stenosis in the extracranial segment of the cerebral blood supply artery
Indications.
Symptomatic stenosis with a diameter stenosis of ≥70%. The stenosis is usually measured by the NASCET method, i.e., [1-(distal normal vessel diameter – narrowest diameter of the stenotic segment)/distal normal vessel diameter] × 100%.
Contraindications.
Same as for intravertebral artery stenting.
Perioperative treatment and monitoring of endostenting for stenosis of the cerebral blood supply artery in the extracranial segment.
From 3 days before surgery, take 250 mg of oral Raltegravir or 75 mg of clopidogrel 2/day and change to 1/day 3 days after surgery.
Oral enteric aspirin 300mg/day from 3 days before surgery, which can be taken for a long time after surgery if the patient is not unwell.
From 2 hours before surgery, nimodipine 0.5-2mg was pumped intravenously to control blood pressure at 110-120/70-80mmHg.
Intraoperative analgesic and sedative anesthetic monitoring was used.
Intraoperative TCD and EEG monitoring were used.
Intraoperative ACT monitoring was used to guide heparin administration.
Immediate postoperative neurological function evaluation was done.
After sheath removal, the patient was laid flat for 24 hours, local conditions were noted, and blood pressure, pulse, urine output, dorsalis pedis artery, state of consciousness, and neurological function were monitored.
If there is no bleeding complication, rapid coagulation avoidance 0.4-0.6 ml is injected subcutaneously q12h×3 days.
Routine use of broad-spectrum antimicrobial agents for 3 days postoperatively.
Intracranial segmental cerebral blood supply artery stenosis endoprosthesis
① Indications.
Symptomatic, recurrent, drug-uncontrollable hypovolemic transient ischemic attacks (TIAs).
There is a clear correspondence between the site of stenosis of the cerebral blood supply artery and the patient’s symptoms of TIAs.
The type of stenosis is Mori type A lesion, and type B lesions should be considered with caution.
The endoprosthesis is expected to reach the target vessel site.
② Conditions in which endostenting is not appropriate.
Non-‘offender’ lesions, or where the patient would not benefit from lesion opening.
Mori C-type lesions.
Significant tortuosity of the pathway vessel that prevents passage of the internal stent.
Other contraindications refer to those for vertebral artery endoprosthesis.
(iii) Perioperative treatment and monitoring of endostenting for stenosis of the cerebral blood supply arteries in the intracranial segment.
From 3 days before surgery, take 250mg or clopidogrel 75mg 2/day orally, and change to 1/day 3 days after surgery.
Oral enteric aspirin 300mg/day from 3 days before surgery, which can be taken for a long time after surgery if the patient is not unwell.
From 2 hours before surgery, nimodipine 0.5-2mg was pumped intravenously to control blood pressure at 110-120/70-80mmHg.
Intraoperative analgesic and sedative anesthetic monitoring was used. For basilar artery angioplasty, tracheal intubation and general anesthesia should be performed.
Intraoperative TCD and EEG monitoring is used.
Intraoperative ACT monitoring is used to guide heparin administration.
Immediate postoperative neurological evaluation is performed.
Immediate postoperative CT scan is performed to exclude complications of cerebral hemorrhage and subarachnoid hemorrhage.
After sheath removal, the patient was laid flat for 24 hours, local conditions were noted, and blood pressure, pulse, urine output, dorsalis pedis artery, state of consciousness, and neurological function were monitored.
For those without bleeding complications, rapid coagulation avoidance 0.4-0.6 ml was injected subcutaneously q12h×3 days.
Routine use of broad-spectrum antimicrobial agents for 3 days postoperatively.
Vertebral artery endoprosthesis.
① Indications.
A Patients with symptomatic (TIA or non-disabling ischemic stroke of the vertebrobasilar system) with ≥70% diameter stenosis of the vertebral artery combined with occlusion of the contralateral vertebral artery.
B Symptomatic dominant vertebral artery stenosis.
C Symptomatic bilateral vertebral artery stenosis.
D Symptomatic nondominant vertebral artery stenosis, where the vertebral artery on that side continues directly with the posterior inferior cerebellar artery (PICA) and the patient’s symptoms are related to inadequate blood supply to the ipsilateral PICA region.
E Asymptomatic vertebral artery stenosis, but the angioplasty helps to improve the blood supply to the collateral branch (e.g., the patient has a concomitant carotid occlusion).
② Contraindications.
A Combined intracranial tumor or AVM.
B Severe disability due to stroke or dementia.
C Previous stroke within 6 weeks.
D No suitable vascular access.
E Patient or patient’s family does not consent.
Endocranial stenting of the subclavian artery.
① Indications.
Symptomatic stenosis or occlusion with diameter stenosis ≥ 70%, causing subclavian artery steal syndrome or ischemia of the affected upper limb.
② Contraindications.
Chronic occlusion with a flat head at the occluded end; severe angular lesions; no suitable vascular access; patient or patient’s family does not consent.
Deciding between carotid endarterectomy or angioplasty
Intracranial-extracranial vascular bypass
Intracranial-extracranial vascular bypass to create a bypass is not recommended for patients with TIA (Class A recommendation). A subgroup of patients with anterior circulation ischemia that does not respond to medications and is associated with hemodynamic disturbances may be indicated for vascular bypass. Patients with Moyamoya disease may benefit from intracranial-extracranial bypass (Class C recommendation).