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X-ray signs of a stroke
Last reviewed: 20.11.2021
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Disorders of cerebral circulation lead to a variety of clinical effects - from transient ischemic attacks to stroke, the third most frequent cause of death. In most cases, a blood flow disorder is associated with an atherosclerotic vascular lesion that initially may not be manifested with too expressive symptoms - headache, memory impairment, sleep disorders, etc.
Ultrasound examination of the vessels of the neck plays an important role in the recognition of chronic disorders of cerebral circulation.
Atherosclerosis can affect intracerebral vessels, but much more often it develops in the extracranial parts of the arteries that supply blood to the brain. Most often, changes develop in the field of bifurcation of the common carotid artery and here it can be successfully eliminated by endarterectomy and reconstructive operations on brachiocephalic vessels.
Ultrasound diagnosis is carried out using one-dimensional Doppler and two-dimensional color Doppler mapping. On dopplerograms determine the position, shape and condition of the lumen of blood vessels. In this case, it is possible to register even small arteries narrowing and separate atherosclerotic plaques on their inner surface. Further, the blood flow in the brachiocephalic vessels is changed, the asymmetry of the blood flow velocity in both carotid or vertebral arteries, the decrease in the blood flow velocity in any of the vessels, the vortex and retrograde blood movements.
In those cases when the question of endovascular or surgical treatment is raised, angiography, or CT or MRI angiography is performed. Angiograms make it possible to most accurately assess the state of both brachiocephalic and cerebral vessels.
In the diagnosis of acute disorders of cerebral circulation - infarcts, intracerebral and shell hemorrhages - currently the main role is played by CT and MRI.
Infarction occurs due to blockage of the cerebral vessel. It is accepted to distinguish three forms of cerebral infarction: extensive, lacunar and subcortical atherosclerotic encephalopathy. In the first hours after the development of the infarct, changes on computer tomograms are not detected, but after 6-8 hours they reveal an indistinctly outlined region of reduced density with indistinct edges, which corresponds to the edema zone. On magnetic resonance tomograms performed in the T2-weighted image mode, the edema is detected earlier than on the computer. Within 2-5 days, the contours of the infarct become more distinct and it is better noticeable that it has a wedge shape and in some direction reaches the cortical layer the brain. Large foci of infarct often occur in the middle cerebral artery. A few weeks later the swelling disappears. Often, a hemorrhagic component may appear in the infarction zone, which is well visualized by CT.
As the infarct is organized, its area can become virtually indistinguishable from the image of the surrounding brain tissue. However, then the density of the affected area again decreases, because after 1-2 months in it, as a rule, a postinfarction cyst is formed, surrounded by an atrophic brain tissue. As a result of the scar process, the nearest department of one of the cerebral ventricles is pulled to the infarction zone.
Intracerebral or sheath hemorrhage (hematoma) is immediately determined on a computer tomogram as a zone of increased density. This is because the absorption of X-ray radiation by blood (52 HU) and red blood cells (82 HU) exceeds that of the brain substance (30-35 HU). In the area of intracerebral hemorrhage, the absorption is 40-90 HU, and this region is especially noticeable, since the edema zone (18-28 HU) is located around it.
If the hemorrhage is accompanied by the breakthrough of blood into the cerebrospinal fluid, then the areas of increased density are determined in the cerebral ventricle. Gradually, the intensity of the shadow of hemorrhage decreases, and then in its place is usually formed posthemorrhagic cyst. Subdural and epidural hematomas also cause areas of increased density, but there is no edema around them. In addition, they are adjacent to the bones of the skull and have an oval or ribbon-like shape. Naturally, large hematomas cause displacement of brain structures, including cerebral ventricles.
In recognition of defects in the development of cerebral vessels and their aneurysms, the tone prescribes, of course, angiography. However, certain data can be obtained with non-invasive studies - CT and MRI. Angiograms determine the position, shape and size of the aneurysm and the presence of a thrombus in it. Aneurysms of the cerebral arteries are usually small - 0.3-0.7 cm in diameter. The most frequent aneurysms are located in the front communicative and middle cerebral arteries. In 25% of patients, aneurysms have a multiple character.
Angiograms can detect arteriovenous anastomoses and arteriovenous deformations. They are characterized by the presence of a large number of dilated vessels with blood shunting directly from the arterial bed to the venous (there is no capillary network). With a sufficient amount of malformation, it can also be suspected when analyzing computer tomograms.