Cerebrovascular disease is one of the three leading causes of death in humans today. About 1.8 million new cases and 1.1 million deaths occur each year nationwide, and about 3/4 of those who survive the onset of stroke lose their labor force to varying degrees. Among stroke patients, 75% to 90% are ischemic strokes. Therefore, it is very important to strengthen clinical and experimental research on ischemic cerebrovascular disease and improve the diagnosis and treatment.
At present, the treatment of ischemic cerebrovascular disease is broadly divided into three categories: drug therapy, surgical therapy and endovascular therapy. As early as the early 1950s, Spence (1951) in the United States was the first to carry out carotid endarterectomy.
Over the past half century, endarterectomy has stood the test of time and has become one of the main treatments for ischemic cerebrovascular disease today.
Carotid endarterectomy is performed on patients with carotid atherosclerosis. These patients often present with transient ischemic attacks (TIA), including transient monocular blindness (TMB) and transient hemispheric attacks (THA). In the interictal period, there are mostly no abnormalities except for a possible murmur on neck auscultation and a possible retinal artery embolism on fundus examination. Carotid Doppler ultrasound (TCD) can confirm the presence of atherosclerotic plaque and determine the degree of stenosis.
Magnetic resonance angiography (MRA) can also show the location and extent of carotid artery stenosis. The advantage of both is that they are non-invasive and can be widely used for screening of high-risk patients. The disadvantage is that some anatomic variants, such as arterial loops or nodules, can cause false positives on Doppler ultrasound; either TCD or MRA may overestimate the degree of stenosis.
Therefore, in all cases where TCD and/or MRA suggest complete occlusion of the carotid artery, digital subtraction cerebral angiography (DSA) should be performed, which can show exactly the site, extent and degree of stenosis and other pathological changes that may be present (e.g., intracranial artery stenosis or aneurysm).
The indication for carotid endarterectomy depends on the clinical presentation of the patient and the characteristics of the lesion.
For patients with TIA, the following manifestations are met.
1. multiple episodes with confirmed corresponding carotid artery stenosis;
2. single episode but carotid stenosis >70%;
3. ulcerative or soft lesions in the carotid artery (mainly composed of lipids, cellular debris and bleeding);
4.Anti-platelet therapy cannot prevent recurrence of TIA. All should be considered for surgery.
Those with frequent TIA episodes, sudden disappearance of pre-existing neck murmur, highly severe carotid stenosis (>90%) or thrombosis should have early or even emergency surgery.
TIA is undoubtedly the best indication for carotid endarterectomy. It is well documented that after the first TIA, if not treated, 20% to 45% will develop a complete stroke within 3 to 4 years, while carotid endarterectomy can reduce the incidence to 3% to 4%. In addition to TIA, surgery should also be considered in patients who have already had a stroke and whose examination confirms the presence of carotid stenosis.
This is because studies have shown that 60% of patients with ischemic stroke of the carotid system recur within 2 years of the initial onset; 50% of patients eventually die from one or more such recurrences. Ischemic stroke due to extracranial carotid lesions has an annual recurrence rate of 5% to 20%, reaching 50% at 5 years. If the first stroke is treated with carotid endarterectomy. The annual recurrence rate can be reduced to 2%. Of course, in stroke patients, the purpose of endarterectomy is not to improve the existing dysfunction but to prevent another stroke.
Carotid endarterectomy has been refined over the decades. However, intraoperative shunts are still inconsistent, both routinely and never used. Most scholars believe that intraoperative shunting should be done according to the patient’s specific situation and intraoperative monitoring results: if the contralateral carotid artery is severely stenosed or occluded, or if the affected carotid artery has an important role in the vertebrobasilar circulation and the EEG or TCD changes significantly after blocking the carotid artery, shunting should be done; other patients should not be shunted.
After the 1990s, although some aspects of carotid endarterectomy are still controversial and the procedure itself has certain complications, its effectiveness in preventing ischemic stroke has been recognized worldwide. This procedure has long been prevalent in developed countries. In recent years, despite the emergence of new techniques such as endovascular angioplasty (including stenting), the status of carotid endarterectomy has not been shaken because it can only achieve the goal of dilating the artery without eliminating the source of the embolus.
Carotid endarterectomy was carried out late in China, and vertebral endarterectomy has not yet started, which is far from the developed countries. The reason for this is the traditional belief that ischemic cerebrovascular disease in the East is mainly intracranial. In fact, most ischemic cerebrovascular patients (especially TIA) in China do not undergo systematic or even minimal examination.
Once the disease develops, a CT scan is performed at most, except for cerebral hemorrhage, and then the diagnosis of “cerebral thrombosis” is made and vasodilatation and thrombolytic therapy are given. As to whether the thrombosis is formed and whether the lesion is intracranial or extracranial, few people have studied it in depth.
The concept formed on this basis lacks a basis. In recent years, some predecessors and knowledgeable people in the neurosurgery field in China have written articles calling for the active development of surgical treatment of ischemic cerebrovascular disease, and included it in the national “Ninth Five-Year Plan” key research topics.
We believe that with the close cooperation between the staff of neurosurgery and interventional neuroradiology, the diagnosis and treatment of ischemic cerebrovascular disease in China will make a new leap.