Posterior circulation ischemia is a common ischemic cerebrovascular disease, accounting for about 20% of ischemic strokes. Today, let’s learn the Chinese expert consensus on posterior circulation ischemia! Source: Neurosurgery I. Understanding of posterior circulation ischemia and its definition and significance The posterior circulation, also known as the vertebrobasilar system, consists of the vertebral artery, the basilar artery and the posterior cerebral artery, which mainly supplies blood to the brainstem, cerebellum, thalamus, occipital lobe, part of the temporal lobe and the superior spinal cord. Posterior circulation ischemia is a common ischemic cerebrovascular disease, accounting for approximately 20% of ischemic strokes. In the 1950s, some patients with transient ischemic attack (TIA) of the carotid system were found to have severe stenosis or occlusion of the extracranial segment of the carotid artery, which was presumed to be caused by the relative ischemia of the tissue in the vascular distribution area supplied by the collateral circulation only, called “carotid insufficiency”. carotid insufficiency). By extending this concept to the posterior circulation, the concept of “vertebrobasilar insufficiency” (VBI) was developed. As can be seen, the classical concept of VBI has two meanings: clinically, it refers to TIA of the posterior circulation, and etiologically, it refers to hemodynamic hypoperfusion due to severe stenosis or occlusion of the great arteries. After the 1970s, it became clear that the only two forms of ischemia in the carotid system were TIA and infarction, and the concept of “carotid insufficiency” was no longer used. However, due to the lag in the understanding of posterior circulation ischemia, the concept of VBI is still widely used and has given rise to some inaccurate perceptions: for example, dizziness/vertigo is often attributed to VBI; cervical spine osteophytes are regarded as an important cause of VBI; and the concept of VBI has been generalized to a state that is neither normal nor ischemic. These situations are especially serious in China, resulting in unclear concepts, unclear diagnostic criteria, and irregular disposition of VBI. 2. The current state of understanding of posterior circulation ischemia: After the 1980s, with the deepening of clinical research and the development of research techniques, there are several important understandings of the clinical and etiological factors of posterior circulation ischemia: (1) the main etiology of posterior circulation ischemia is atherosclerosis, while cervical spine osteophytes are only a rare case; (2) the most important mechanism of posterior circulation ischemia is embolism; (3) neither clinical nor imaging examinations cannot reliably define a state that is neither normal nor ischemic; (4) although dizziness/vertigo is a common symptom of posterior circulation ischemia, the common cause of dizziness/vertigo is not posterior circulation ischemia. Based on the above understanding, the concept of VBI has been replaced by the concept of posterior circulation ischemia internationally, and VBI is no longer used in the International Classification of Diseases. 3. Definition of posterior circulation ischemia: It refers to TIA and cerebral infarction of the posterior circulation. Its synonyms include ischemia of the vertebrobasilar system, TIA and cerebral infarction of the posterior circulation, vertebrobasilar artery disease, and vertebrobasilar thromboembolic disease. Given that MRI diffusion-weighted imaging (DWI) finds that about half of posterior circulation TIAs have definite infarct changes and the boundary between TIA and cerebral infarction is becoming increasingly blurred, the use of posterior circulation ischemia to cover T/A of the posterior circulation and cerebral infarction is beneficial for clinical operation. (1) Atherosclerosis is the most common vascular pathological manifestation of posterior circulation ischemia. The mechanisms leading to posterior circulation ischemia include: large artery stenosis and occlusion causing hypoperfusion, thrombosis and arterial-derived embolism. Atherosclerosis occurs in the beginning and intracranial segments of the vertebral arteries. (2) Embolism is the most common pathogenesis of posterior circulation ischemia, accounting for about 40% of emboli, which mainly originate from the heart, aorta and vertebral basilar artery. The most common sites of embolism are the intracranial segment of the vertebral artery and the distal basilar artery. (3) Penetrating small artery lesions, including vitreous lesions, microaneurysms and atherosclerotic lesions at the initiation of small arteries, occur in the pontocerebrum, midbrain and thalamus. 2) Major risk factors for posterior circulation ischemia: Similar to carotid system ischemia, the main risk factors are lifestyle (diet, smoking, lack of activity, etc.), obesity and various vascular risk factors, the latter including hypertension, diabetes, hyperlipidemia, heart disease, history of stroke/TIA, carotid artery disease and peripheral vascular disease, in addition to non-modifiable age, gender, race, genetic background, family history, and personal history. 3. Cervical osteophytes are not the main cause of posterior circulation ischemia: It was previously thought that turning the head/neck could cause the osteophytes to compress the vertebral artery, resulting in posterior circulation ischemia and dizziness/vertigo due to the sensitivity of the vestibular nerve nucleus to ischemia. This model of hypothesis instead of evidence is a major cause of confusion in the diagnosis of VBI. In contrast, clinical studies have demonstrated that cervical osteophytes are by no means a major risk factor for posterior circulation ischemia, as there is no significant difference in the degree of cervical osteophytes between middle-aged and elderly subjects with or without posterior circulation ischemia, but only in vascular risk factors; serial dynamic imaging of the vertebral artery has only seen isolated arterial compression due to osteophytes; Doppler ultrasonography after neck rotation has not been performed between those with or without posterior circulation symptoms The rate of extracranial segment compression of the vertebral artery did not differ between those with and without posterior circulation symptoms. The main clinical manifestations of posterior circulation ischemia: common symptoms of posterior circulation ischemia: dizziness/vertigo, numbness of limbs/head and face, weakness of limbs, headache, vomiting, diplopia, transient loss of consciousness, visual disturbance, unstable walking or fall. Common signs of posterior circulation ischemia: eye movement disorders, limb paresis, sensory abnormalities, gait/limb ataxia, dysarthria/swallowing disorders, visual field defects, hoarseness, Homer syndrome, etc. The presence of crossover between neurological damage on one side of the brain and motor-sensory damage on the other side is a characteristic manifestation of posterior circulation ischemia. Common syndromes of posterior circulation ischemia are: posterior circulation TIA, cerebellar infarction, lateral delayed brain syndrome, basilar artery acinar syndrome, Weber syndrome, atresia syndrome, posterior cerebral artery infarction, lacunar infarction (motor hemiparesis, ataxia hemiparesis, dysarthria, clumsy hand syndrome, pure sensory stroke, etc.). The dense structure of the brainstem and the non-one-to-one correspondence between vascular innervation and neural structure determine that the majority of posterior circulation ischemia presents as multiple overlapping clinical manifestations, rarely as a single symptom or sign. Simple dizziness/vertigo, syncope, fall episodes or transient loss of consciousness are rarely caused by posterior circulation ischemia. 3. Evaluation and diagnosis of posterior circulation ischemia: Detailed history, physical examination and neurological examination are the basis of diagnosis. It is important to carefully understand the history, especially the occurrence, form, duration, concomitant symptoms, evolution and possible precipitating factors of symptoms; to pay attention to various vascular risk factors; to focus on the examination of cerebral nerves (vision, eye movements, facial sensation, hearing, vestibular function) and ataxia. In those with dizziness/vertigo as the main complaint, Dix-Hallpike examination should always be performed to exclude benign episodic positional vertigo. Neuroimaging, mainly MRI, should be performed in all patients with suspected posterior circulation ischemia. DWI is most valuable for the diagnosis of acute lesions. Cranial CT examination is susceptible to bone artifacts and has little diagnostic value, and is only applicable to exclude hemorrhage and patients who cannot undergo MRI examination. Various vascular examinations should be actively carried out. Digital subtraction angiography, CT angiography, MRI angiography and vascular Doppler ultrasonography can help to detect and clarify large intracranial and extracranial vascular lesions. Each examination has its own characteristics, and there is a lack of correlation studies between different examinations. Transcranial Doppler ultrasonography (TCD) can detect stenosis or occlusion of the vertebral artery, but it cannot be the only basis for the diagnosis of posterior circulation ischemia. A variety of cardiac examinations can help to clarify embolism from the heart or aortic arch. Imaging of the cervical spine is not the first choice or important examination. IV. Prevention and treatment of posterior circulation ischemia 1. Acute phase treatment: There is still a lack of results from large randomized controlled studies specifically on posterior circulation ischemia, so the acute phase management of posterior circulation ischemia is the same as for anterior circulation ischemic stroke. An organized treatment model for stroke units should be actively pursued. Intravenous thrombolysis with recombinant tissue-type fibrinogen activator (rt.PA) can be performed in appropriate patients within 3 h of onset. The time window for treatment can be relaxed for those who are eligible for intravenous thrombolysis. For all patients who are not suitable for thrombolytic therapy and have no contraindication, they should be treated with aspirin 100–300 mg/d. Other treatment measures can be referred to the relevant treatment guidelines at home and abroad. 2. 2. Prevention: Control various vascular risk factors with reference to relevant domestic and international prevention and treatment guidelines. In view of the prevalence of embolism, etiological examination should be actively carried out. Antithrombotic therapy should be administered to those with a clear diagnosis. The use of antiplatelet agents alone or in combination has an important preventive role. The efficacy of angioplasty stenting should be explored. 3. missionary education: actively carry out continuing re-education of posterior circulation ischemia especially for physicians, update the concept and knowledge, and stop using the concept of VBI. Propaganda should be strengthened to correctly grasp the early manifestations of posterior circulation ischemia and achieve early detection and diagnosis. The risk factors of posterior circulation ischemia should be correctly understood, and a scientific view of prevention should be established. V. Clinical research on posterior circulation ischemia Clinical research in this field should be actively promoted in China, and a national or regional registration system and database should be established. The diagnostic criteria and prevention measures of posterior circulation ischemia should be standardized. VI. Several important understandings about posterior circulation ischemia 1. Posterior circulation ischemia includes TIA and cerebral infarction in the posterior circulation. 2. The main etiology of posterior circulation ischemia is the same as that of anterior circulation ischemia, and cervical spondylosis is not the main etiology. 3. Dizziness/vertigo is a common manifestation of posterior circulation ischemia, but the common cause of dizziness/vertigo is not posterior circulation ischemia. 4. The diagnosis, treatment and prevention of posterior circulation ischemia should be consistent with that of anterior circulation ischemia. Experts in the Consensus Group (in Chinese pinyin order by last name): Haibo Chen (Beijing Hospital) Kangning Chen (Southwest Hospital of the Third Military Medical University) Xiaochun Chen (Union Hospital of Fujian Medical University) Yan Cheng (General Hospital of Tianjin Medical University) Qiang Dong (Huashan Hospital of Fudan University, Shanghai) Suijun Dong (Xiamen First Hospital) Jiachun Feng (First Hospital of Jilin University) Mao-Lin He (Beijing Saitan Hospital) Chang-Lin Hu (Second Hospital of Chongqing Medical University) (Second Affiliated Hospital of Chongqing Medical University) Xingyue Hu (Run Run Run Shaw Hospital, Zhejiang University School of Medicine) Xueqiang Hu (Third Affiliated Hospital of Sun Yat-sen University) Xiaolin Ji (Fujian Provincial Hospital) Senyang Lang (301 Hospital of the People’s Liberation Army, Beijing) Yangsheng Li (Renji Hospital, Shanghai Jiaotong University School of Medicine) Chunfeng Liu (Second Affiliated Hospital of Soochow University) Ming Liu (West China Hospital of Sichuan University) Xiaoping Pan (Guangzhou First People’s Hospital) ) Qi Xiaokun (Beijing Naval General Hospital) Wang Xin (Zhongshan Hospital of Fudan University, Shanghai) Wang Lijuan (Guangdong Provincial People’s Hospital) Wang Lime (The First Hospital of Fujian Medical University) Wang Shaoshi (Shanghai First People’s Hospital Branch) Wang Wei (Tongji Hospital of Huazhong University of Science and Technology) Wang Weizhi (The Second Affiliated Hospital of Harbin Medical University) Wang Yilong (Beijing Tiantan Hospital) Wang Congjun (Beijing Tiantan Hospital) Yu Huafeng (Beijing Tongren Hospital, Capital Medical University) Zeng Jinsheng (The First Affiliated Hospital of Zhongshan Medical University) Zhang Chaodong (The First Affiliated Hospital of China Medical University) Zhang Suming (Tongji Hospital of Huazhong University of Science and Technology) Zhang Zhuo (Beijing Anzhen Hospital) Zhang Weiwei (General Hospital of Beijing Military Region) Zhou Shengnian (Qilu Hospital of Shandong University)