Cerebral infarction can produce different clinical manifestations depending on the site of involvement, such as hemiparesis, speech and hearing impairment, and in severe cases, coma or even life-threatening. Some patients only show functional neurological damage caused by cerebral white matter ischemia, such as memory, calculation or disorientation, and drowsiness. Physical examination: Patients with carotid artery stenosis may have weakened or absent carotid pulsations, audible carotid murmurs, retinal anemia, etc.
Carotid stenosis is clinically manifested by ischemic symptoms in the brain and eyes. If the lesion involves the anterior cerebral circulation supply artery, i.e., the common and internal carotid arteries. The typical clinical symptoms are transient ischemic attack (TIA), i.e., transient limb weakness and numbness, and transient hemiplegia. If the lesion involves the posterior cerebral circulation, i.e., vertebral artery, it may show signs of basilar artery ischemia, such as vertigo, syncope and nausea. In severe cases, stroke or cerebral infarction may occur.
Imaging methods
Currently, imaging methods commonly used for carotid stenosis include color flow Doppler ultrasound ( CFDS), CTA, MRA, DSA, and intravascular ultrasound (IVUS). Except for emergency patients, at least two of the following imaging tests should be performed preoperatively for cross-corroboration
CFDS: including real-time sonography, Doppler hemodynamics and 3D angiography, which can provide accurate information on lesion extent, stenosis degree, plaque nature, vessel wall thickness and blood flow velocity. However, the diagnostic results of CFDS are greatly affected by the experience of the operator and the condition of the equipment, and are suitable for screening patients with suspected carotid artery stenosis.
CTA: Its greatest advantage is that it can distinguish microscopic density contrast differences and has a unique advantage in diagnosing vessel wall calcification; however, in terms of determining the degree of luminal stenosis, the compliance rate with angiographic diagnosis is only about 90%.
MRA:The diagnostic effect of carotid stenosis is similar to that of CTA, and it is worse than CTA in terms of the visualization and judgment of calcification. MRA tends to exaggerate the lesion and often fails to distinguish between severe stenosis and occlusion. The diagnostic compliance rate with angiography is similar to that of CTA, at around 90%.
DSA: It is still the “gold standard” for the diagnosis of vascular lesions, accurately demonstrating the degree and extent of stenosis, and is the ultimate basis for treatment planning. The measurement and grading of carotid stenosis on DSA is based on the North American Society for Carotid Surgery and Research (NASCET) criteria. That is, stenosis rate = (1- A/B) × 100% (A: diameter of the vessel at the narrowest point; B: diameter of the normal internal carotid artery distal to the stenosis). The degree of stenosis is classified as mild (stenosis rate 0~29%), moderate (stenosis rate 30%~69%) and severe (stenosis rate 70%~99%).
Treatment principles and methods
Indications
1.Primary indications: Imaging confirmed carotid artery stenosis rate of 70% with clear related symptoms and signs; carotid artery stenosis rate of 50% or more with clear ulcer formation and/or unstable plaque.
Secondary indications: asymptomatic unilateral carotid stenosis with a lumen stenosis rate (diameter) > 80%; asymptomatic bilateral carotid stenosis with a stenosis diameter > 70%; asymptomatic bilateral carotid stenosis with a stenosis diameter of 50% to 70%, but major surgery requiring general anesthesia, in order to prevent intraoperative cerebral ischemia can be performed unilaterally (dominant side) CAS before surgery.
3.Special indications: If the imaging confirms complete occlusion of the carotid artery, but the length of the occluded segment is ≤10 mm, and the distal outflow tract is patent with clear related symptoms and signs, special indications are available under technical feasibility.
Contraindications
1.Serious neurological disorders, such as complete loss of brain function on the side of the lesion, paralysis, etc.
2.Complete occlusion of carotid artery with lesion length >10 mm, accompanied by imaging confirmed intravascular thrombosis and multi-segment stenosis.
3.Ipsilateral intracranial arteriovenous malformation or aneurysm with bleeding tendency, which cannot be treated in advance or at the same time.
4.Patients who have had intracranial hemorrhage within 3 months or large cerebral infarction within 4 weeks.
5.Severe cardiac, hepatic and renal dysfunction, contrast allergy and other contraindications to angiography.
Treatment methods
The choice of methods: direct stent implantation is recommended for atherosclerotic carotid stenosis, and balloon dilation alone is not recommended; balloon dilation and angioplasty (PTA) is recommended for fibromuscular dysplasia (FMD) and carotid stenosis caused by aortitis, and stent implantation is recommended for complications such as entrapment during dilation; stent implantation is recommended for atherosclerotic carotid stenosis, and balloon dilation and angioplasty is recommended for atherosclerotic carotid stenosis. In atherosclerotic carotid artery stenosis, the use of an EPD is recommended for stenting.