V. Posterior circulation ischemia 1.What is posterior circulation ischemia? 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, hippocampus, occipital lobe, part of the temporal lobe and spinal cord. Posterior circulation ischemia (PCI) is a common ischemic cerebrovascular disease, accounting for approximately 20% of ischemic strokes. 2. What are the causes and pathogenesis of posterior circulation ischemia? (1) Atherosclerosis is the most common vascular pathology manifested by PCI. The mechanisms leading to PCI include: large artery stenosis and occlusion causing hypoperfusion, thrombosis, arterial-derived embolism, and arterial entrapment. Atherosclerosis is more likely to occur in the beginning and intracranial segments of the vertebral artery. (2) Embolism is the most common pathogenesis of PCI, accounting for about 40% of cases. Emboli mainly originate from the heart, the aortic arch, the beginning segment of the vertebral artery, and the 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 include lipohyalinosis, microaneurysms and atherosclerotic lesions at the beginning of small arteries and other damages, which are most commonly found in the pontine brain, midbrain and thalamus. 3.What are the clinical manifestations of posterior circulation ischemia? The brainstem is an important site of neural activity, in which the cerebral nerves, the reticular superior activating system and important upstream and downstream conduction bundles pass. When the blood supply is impaired and neurological impairment occurs, various but overlapping clinical manifestations will occur. Thus the clinical manifestations of PCI are diverse, lack a stereotypical or fixed form, and are difficult to identify clinically. Common clinical symptoms of PCI include dizziness, vertigo, and vertigo may be accompanied by nausea and vomiting in severe cases. There are also numbness of the limbs or head and face, limb paralysis, abnormal sensation, gait or limb ataxia, dysarthria or dysphagia, fall episodes, hemianopia, hoarseness, etc. 4.What tests are needed to confirm the diagnosis of posterior circulation ischemia? Cervical vascular ultrasound, craniocervical CTA (angiography), etc. can determine the presence of vascular lesions in the posterior circulation. 5.What are the risk factors for posterior circulation ischemia? There are mainly non-adjustable factors and adjustable factors. The non-modifiable factors include age, gender, race, genetic background, family history, personal history, etc. The modifiable factors include lifestyle (diet, smoking, lack of activity, obesity, etc.) and various vascular risk factors, the latter including hypertension, diabetes, hyperlipidemia, heart disease, history of stroke/transient ischemic attack (TIA), carotid artery disease, peripheral vascular disease, hypercoagulable state, hyperhomocysteinemia, and oral medication. cysteinemia, oral contraceptives, etc. 6. Is cervical spine osteophyte a major cause of posterior circulation ischemia? In the past, it was thought that turning the head/neck caused the osteophytes to compress the vertebral artery, resulting in posterior circulation ischemia, and because the vestibular nerve nucleus is sensitive to ischemia, dizziness/vertigo is produced. Numerous clinical studies have proven that aging-related cervical spine osteophytes are by no means a major risk factor for PCI because: (1) PCI patients have cervical spine osteophytes in addition to atherosclerosis, and it is impossible to determine whether the osteophytes, rather than atherosclerosis, cause the disease. There is no significant difference in the degree of cervical spine osteophytes between middle-aged and elderly populations with or without PCI, only differences in vascular risk factors. (2) Pathological studies have demonstrated that the initiating segment of the vertebral artery is the site of atherosclerosis, while the stenosis/occlusion of the intravertebral segment is not severe. 7.Which department should I see for posterior circulation ischemia? When a patient is highly suspected of having posterior circulation ischemia, neurology can be preferred for diagnosis and treatment, but it is necessary to perform examination of vestibular function, especially varus test to exclude BPPV.