Right middle cerebral artery stenosis

It is often said that it is important to have a smart brain. The brain is the central organ that issues commands and thinks about problems, and plays a very important role in the human body. The left side of the brain is responsible for mathematical and logical thinking, while the right side of the brain is responsible for artistic appreciation and imagination. Both are indispensable. What will happen when the right middle cerebral artery is narrowed? Let us find out together.

It is a direct continuation of the internal carotid artery and does not participate in the formation of the cerebral arterial circle. Before entering the lateral cerebral sulcus, it gives off many central branches to supply the internal capsule and basal ganglia; on the dorsolateral surface of the cerebrum, its main trunk runs in the lateral cerebral sulcus and finally terminates at the angular gyrus artery. Along the way, it gives off many cortical branches, which are widely distributed in the dorsolateral surface of the cerebral hemisphere except the frontal pole and occipital lobe, including below the middle frontal gyrus, the lower 3/4 of the precentral gyrus and postcentral gyrus, the inferior parietal lobule, the upper edge or upper half of the superior, middle and inferior temporal gyri, the medial and lateral surfaces of the temporal pole and the insular cortex, and the cortical area before the lateral occipital sulcus of the occipital lobe. These involve the motor area, pre-motor area, somatosensory area, auditory area and communication area. If the central branch of the middle cerebral artery (most commonly the lenticulostriate artery) bleeds, that is, internal capsule hemorrhage, the typical "three hemiplegia" symptoms may appear, namely paralysis of the limbs, lower facial muscles and tongue muscles on the contralateral side of the bleeding, contralateral hemisensory impairment, and contralateral homonymous hemianopsia.

If the middle cerebral artery is blocked near the lateral sulcus, paralysis of the contralateral upper limb, facial muscles and tongue muscles, and sensory disorders of the contralateral upper limb and head and face may occur, including loss of stereopsis and inability to distinguish different degrees of stimulation; if it occurs in the dominant hemisphere, the patient may also experience motor aphasia, which is caused by the involvement of the language motor area in the posterior part of the inferior frontal gyrus; when the supramarginal gyrus is involved, apraxia or apraxia occurs; when the angular gyrus is involved, alexia occurs; sensory aphasia may occur if the posterior part of the superior temporal gyrus is involved; and agraphia occurs if the posterior part of the middle frontal gyrus is involved.

Diseases related to the middle cerebral artery

1. Middle cerebral artery aneurysm: Middle cerebral artery aneurysm accounts for about 18% to 20% of the total number of intracranial aneurysms. 85% of them occur in the supracervical segment of the middle cerebral artery, namely the limnus isula, and the remaining 15% are located in other parts of the middle cerebral artery. There are more giant and spindle-shaped ones. The most common symptoms are ischemia and local space-occupying symptoms in the area supplied by the middle cerebral artery, manifested as convulsions, mild hemiplegia, mental symptoms, etc. Those on the dominant side also have aphasia. Bleeding can cause spontaneous SAH or intracerebral hematoma. Half of the patients have mild hemiplegia and about 1/3 have aphasia. In hemiplegia, upper limb paralysis is more severe than lower limb paralysis. Among all intracranial ANs, middle cerebral artery aneurysms are the most likely to cause seizures.

2. Middle cerebral artery occlusion: It is common in clinical practice, accounting for 79.6% of occlusive cerebrovascular disease. The age of onset is mostly over 40 years old, with a male to female ratio of 3:2. The clinical manifestations are contralateral hemiplegia, hemisensory disturbance, homonymous hemianopsia, complete aphasia, severe disturbance of consciousness and convulsions. Brain herniation (main trunk occlusion) may occur due to cerebral edema and intracranial hypertension. Or it may be internal capsule hemiplegia (there is no significant difference in the degree of paralysis between the upper and lower limbs, and between the proximal and distal limbs), without hemianopsia and sensory impairment, and early atrophy (occlusion of the sagittal branch of the perforating artery - the lenticulostriate artery, which only supplies the pyramidal tract in the internal capsule). Or it may be a progressive stroke, cortical symmetrical hemiplegia (the degree of paralysis is more severe in the head, face and upper limbs than in the lower limbs, and more severe in the distal limbs than in the proximal ones), which may be accompanied by homonymous hemianopsia, general sensory impairment and complex sensory impairment, various types of aphasia, apraxia and agnosia, mild contracture, and may have convulsive attacks.

3. Middle cerebral artery embolic infarction:

Cerebral embolism refers to the result of an embolus entering the blood circulation and suddenly blocking the cerebral arterial system, so it is also called embolic cerebral infarction. It often occurs suddenly and is a complete stroke at the beginning, accounting for 30% to 50% of cerebral infarction. The sources of emboli can be divided into three categories: ① Cardiogenic: mainly seen in patients with subacute infective endocarditis, rheumatic heart disease, mitral stenosis and atrial fibrillation; ② Non-cardiogenic emboli: more common in the detachment of atherosclerotic plaques, and also fat, tumor, and air emboli; ③ Iatrogenic emboli: such as caused by angiography and surgery. This case was caused by angiography and had an acute onset.

CT manifestations: ① Fan-shaped or irregular low-density areas, similar to those of ischemic cerebral infarction; ② High-density or multiple cortical infarction foci with bleeding in large infarct areas, accompanied by signs of bleeding; more than 50% of cerebral infarctions are hemorrhagic infarctions, because the thrombus of the occluded artery often dissolves within 1 to 5 days, the vascular bed in the ischemic area is reopened, the permeability is increased and destroyed, causing excessive perfusion and resulting in hemorrhagic infarction.

The differential diagnosis is mainly: differentiation between cerebral embolism and thrombotic cerebral infarction, which is mainly based on the clinical history summary and the acuteness of onset. CT findings of early hemorrhage in the infarct focus or hemorrhage in multiple infarct focuses are helpful for the diagnosis of cerebral embolism.

How to treat middle cerebral artery stenosis

The middle cerebral artery is one of the main blood supply arteries to the cerebral hemisphere. The main cause of stenosis is atherosclerosis. The thickening of the vascular endothelium or the formation of plaques gradually reduces the inner diameter of the blood vessel. When the middle cerebral artery is severely narrowed or even occluded, its blood supply area becomes ischemic, and contralateral facial paralysis, hemiplegia, sensory impairment, hemianopsia, etc. may occur. If the dominant hemisphere is affected, speech disorders may occur.

For patients with more than 50% stenosis of the middle cerebral artery, corresponding treatment is necessary. If the symptoms are mild, oral medication can be used for treatment and long-term monitoring can be conducted. Once the stenosis worsens, interventional treatment can be considered. For patients with obvious symptoms or severe stenosis, it is recommended to actively use stent angioplasty or balloon dilatation for treatment. Among them, stent angioplasty has certain advantages, but if the cerebral blood vessels are very tortuous, balloon dilatation of the stenotic area can also achieve better results.