Posterior circulation ischemia

Introduction Post-circulatory ischemia refers to the posterior circulation of the carotid system transient ischemic attack (TIA) and cerebral infarction. Synonyms include vertebral basilar artery ischemia, posterior circulation of TIA and cerebral infarction, vertebral basilar artery disease, vertebrobasilar thromboembolic disease. In view of MRI diffusion-weighted imaging, it is found that about half of the posterior circulation TIA has a clear infarct change and the boundary between TIA and cerebral infarction is increasingly blurred. Therefore, post-circulatory ischemia covers the posterior circulation of TIA and cerebral infarction, which is conducive to clinical operation. History of post-circulatory ischemia: In the 1950s, some patients with TIA had severe stenosis or occlusion of the extracranial segment of the carotid artery. It is speculated that the vascular distribution area is only supported by the collateral circulation. The state is called "carotid artery insufficiency". This concept was extended to the posterior circulation, resulting in the concept of "insufficient blood supply to the vertebrobasilar artery." It can be seen that the classic concept of vertebrobasilar insufficiency has two meanings, clinically refers to the posterior circulation of TIA, and the etiology refers to hemodynamic hypoperfusion caused by severe stenosis or occlusion of the aorta. After the 1970s, it was clear that carotid ischemia was only in the form of TIA and infarction, and the concept of "carotid insufficiency" was no longer used. However, due to the lag of understanding of posterior circulation ischemia, the concept of vertebrobasilar insufficiency is still widely used, and some inaccurate understandings are generated: such as dizziness and dizziness, blaming the vertebrobasilar insufficiency; cervical hyperosteogeny As an important cause of vertebrobasilar insufficiency; more generalized the concept of vertebrobasilar insufficiency, it is considered to be a state of neither normal nor ischemic. These conditions are particularly serious in China, resulting in an unclear concept of vertebrobasilar insufficiency, unclear diagnostic criteria, and irregular disposal.

Cause

1. The main etiology and pathogenesis of posterior circulation ischemia

(1) Atherosclerosis is the most common vascular pathological manifestation of posterior circulation ischemia. The mechanisms leading to posterior circulation ischemia include: aortic stenosis and occlusion leading to hypoperfusion, thrombosis, and arterial embolism. Atherosclerosis occurs in the initial and intracranial segments of the vertebral artery.

(2) Embolization is the most common pathogenesis of posterior circulation ischemia, accounting for about 40%. The embolus is mainly derived from the heart, aorta and vertebral basilar artery. The most common sites of embolization are the intracranial segment of the vertebral artery and the distal end of the basilar artery.

(3) Perforating small arterial lesions include atherosclerotic lesions in the glassy, microaneurysm and small arteriosus, which occur in the pons, midbrain and thalamus.

2. Major risk factors for posterior circulation ischemia

Similar to carotid ischemia, except for irreversible age, gender, ethnicity, genetic background, family history, and personal history, mainly lifestyle (diet, smoking, lack of activity, etc.), obesity, and multiple vascular risk factors, The latter include hypertension, diabetes, hyperlipidemia, heart disease, stroke, history of TIA, carotid artery disease and peripheral vascular disease.

Cervical vertebrae hyperplasia is not the main cause of posterior circulation ischemia: in the past, it was thought that the scalp and neck could compress the vertebral artery, leading to posterior circulation ischemia. Because the vestibular nerve nucleus was sensitive to ischemia, it caused dizziness/vertigo. This pattern of hypothesis-replacement evidence is an important cause of confusion in the diagnosis of vertebrobasilar insufficiency. Clinical studies have shown that cervical vertebrae hyperplasia is by no means a major risk factor for posterior circulation ischemia, because there is no significant difference in the degree of cervical hyperplasia between the elderly and the elderly with or without posterior circulation ischemia, only vascular risk Different factors; continuous vertebral artery dynamic angiography only showed arterial compression caused by osteophytes; Doppler ultrasonography after cervical transformation, no vertebral artery extracranial compression in patients with or without post-circulatory symptoms There is a difference in the ratio.

an examination

Related inspection

Angiography Doppler echocardiography CT examination of cardiovascular MRI

1. Common symptoms of posterior circulation ischemia

Dizziness / dizziness, numbness of the limbs / head and face, weakness, headache, vomiting, diplopia, loss of transient consciousness, visual impairment, unstable walking or falling. Common signs of posterior circulation ischemia: ocular dyskinesia, limb paralysis, paresthesia, gait/limb ataxia, dysarthria/swallowing disorder, visual field defect, hoarseness, Horner syndrome, etc. The cross-over manifestation of one-sided cranial nerve damage and the other side of motor sensation damage is a characteristic manifestation of posterior circulation ischemia.

2. Common syndrome of posterior circulation ischemia

Posterior circulation TIA, cerebellar infarction, lateral cerebral cerebral syndrome, basilar artery syndrome, weber syndrome, atresia syndrome, posterior cerebral artery infarction, lacunar infarction (motor hemiparesis, ataxia, hemiparesis, articulation) Obstacle - pickpocket syndrome, pure sensory stroke).

Differential diagnosis

Detailed medical history, physical examination and neurological examination are the basis of diagnosis. Careful understanding of medical history, especially the occurrence, form, duration, accompanying symptoms, evolution process and possible predisposing factors of symptoms; attention should be paid to understanding various vascular risk factors; attention should be paid to cranial nerves (visual, eye movement, facial sensation) , hearing, vestibular function) and the examination of the Mutual Movement. For dizziness/vertigo, the Dix-Hallpike test must be performed to rule out benign paroxysmal positional vertigo. All patients with suspected posterior circulation ischemia should undergo neuroimaging, mainly MRI. DWI has the most diagnostic value for acute lesions. Head CT examination is susceptible to bone artifacts and has little diagnostic value. It is only suitable for patients who are excluded from bleeding and cannot undergo MRI. Various vascular examinations, digital subtraction angiography, CT angiography, MRI angiography, and vascular Doppler ultrasonography should be actively explored to help identify and identify intracranial and extracranial vascular lesions. Various inspections have their own characteristics, and related research in different inspection rooms is still lacking. Transcranial Doppler ultrasonography (TCD) can detect stenosis or occlusion of the vertebral artery, but it cannot be the sole basis for diagnosis of post-circulation ischemia. A variety of cardiac exams help to clarify embolism from the heart or aortic arch. Imaging studies of the cervical spine are not preferred or important tests.

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