Head pathology on computed tomography

CT in traumatic hemorrhages

A direct consequence of a trauma to the skull is a brain contusion accompanied by a hemorrhage. Acute hemorrhage looks like a zone of increased density with edema of surrounding tissues and displacement of nearby brain structures. In patients with anemia, the hematoma appears less dense and may even be isodens (equal density) of normal brain tissue.

If damage to the vessel wall occurs again due to a decrease in perfusion due to the edema of the brain region, signs of hemorrhage may not be detected within hours or, rarely, days after trauma to the skull. Therefore, computed tomography of the head, performed immediately after the trauma of the skull and not showing any pathological changes, does not allow to exclude the development of intracranial hemorrhage in the future. Therefore, if the condition of the patient worsens, a second scan must be performed. After complete resolution of the hematoma, a clearly defined defect with a density equal to (isodensic) CSF is determined.

A brain contusion often leads to epidural, subdural or subarachnoid hemorrhage with possible spreading to the ventricles. Complication of this distribution, as well as subarachnoid hemorrhage, is a violation of the circulation of cerebrospinal fluid due to obstruction of pachyon granulations (arachnoid shell), a Monroe or IV ventricular ventricle. As a result, hydrocephalus may develop with an increase in intracranial pressure and a transcendental cuff of the brain.

Epidural and subdural hematomas also can lead to a significant displacement of brain tissue and median structures. Very often this causes the obstruction of the opposite Monroe aperture and, accordingly, the unilateral expansion of the lateral ventricle of the brain on the side opposite to the bleeding.

[1], [2], [3], [4], [5], [6], [7], [8], [9], [10], [11], [12], [13], [14]

Computed tomography with intracranial hemorrhages

If the hemorrhage spreads into the cavity of the ventricles, the physiological calcifications of the vascular plexuses in the lateral and third ventricles, the epithalamus leash and the pineal gland must be distinguished from fresh hyperdense blood clots. Notice the swelling surrounding the hemorrhage.

When performing a CT scan in the patient's position lying on the back, a horizontal blood level in the posterior horns of the lateral ventricles can be determined due to sedimentation. If the ventricles are dilated, the patient has a real danger of transgenic wedging.

[15], [16], [17], [18], [19], [20], [21], [22], [23], [24], [25], [26], [27], [28], [29]

Subarachnoid hemorrhage (SAH)

Obstructive hydrocephalus caused by SAH is easily determined by the expansion of the temporal ridge ventricles. In such cases it is important to assess the width of the SAP and pay attention to the gyrus of the brain - the lack of clarity indicates a diffuse cerebral edema.

Intracranial hemorrhage

Since children have a very narrow SAP, the presence of SAC can be overlooked. The only sign is a small zone of increased density, adjacent to the sickle. In adults, a small SAA appears as a restricted area of increased density.

Subdural hematoma

Bleeding to the subdural space occurs as a result of a brain contusion, damage to the vessels of the soft dura mater, or rupture of the emissary veins. At first, the hematoma looks like an extended structure of increased density, located along the inner edge of the cranial vault. Unlike epidural hematoma, its outlines are usually uneven and slightly concave from the side of the adjacent hemisphere of the brain. This type of intracranial bleeding is not limited to the sutures of the skull and can spread along the entire surface of the hemisphere.

Subdural hematoma can cause a noticeable shift in the structures of the brain leading to a disruption in the circulation of the cerebrospinal fluid and the insertion of the brainstem into the tentorial incision. Therefore, to determine the further treatment tactics, it is not so important to establish the nature of the hematoma (subdural or epidural), how to determine the magnitude (size) of hemorrhage. Hematomas with a tendency to spread, especially with the threat of cerebral edema, must be removed surgically.

Chronic subdural hematoma looks like a homogeneous zone of reduced density or a non-uniform zone with sedimentation of blood. Especially dangerous are small venous bleeding due to the patient's asymptomatic period and the gradual development of the somnolence - up to the coma. Therefore, a patient with a trauma to the skull and suspected bleeding should always be monitored so that deterioration in the condition can be noticed in time.

[30], [31], [32], [33], [34], [35], [36], [37], [38], [39], [40], [41]

Epidural hematomas

Bleeding to the epidural space usually occurs due to damage to the middle meningeal artery and rarely - from venous sinuses or pachyon bodies (granulations). Most often, they can be found in the temporal parietal region or the posterior cranial fossa, where there is a danger of wedging the tonsils of the cerebellum. Arterial bleeding exfoliates the dura mater from the inner surface of the cranial vault and is visualized on the cut as a biconvex zone of increased density with an even edge on the side of the adjacent hemisphere. The hematoma does not extend beyond the seams between the frontal, temporal, parietal or occipital bones. When small epidural hematomas occur, the biconvex form is not clearly defined, and in this case it is difficult to distinguish it from the subdural hematoma.

It is important to distinguish between a closed fracture of the cranial vault with an intact dura mater and an open fracture of the skull with a risk of secondary infection. A characteristic sign of an open fracture of the skull is the presence of air bubbles in the cavity of the skull, which proves the presence of a communication between the intracranial space and the external environment or paranasal sinuses.

[42], [43], [44], [45], [46], [47], [48], [49], [50], [51], [52]

Computed tomography in stroke

Along with cardiovascular and oncological diseases, stroke is one of the most frequent causes of death. Thrombotic occlusion of the cerebral artery leads to irreversible necrosis of the area of its blood supply. The causes of occlusion are atherosclerotic changes in cerebral vessels or, more rarely, arteritis. Also, the cause of occlusion of cerebral vessels can be embolism from the left heart and from blood clots on atherosclerotic plaques of bifurcation of the common carotid artery.

Typical for embolism is the presence of small infarcted areas of reduced density, located diffusely in both hemispheres and basal ganglia. In the future, the embolism zones look like small, clearly delineated areas with a density equal to (isodense) density of the cerebrospinal fluid. They are called lacunar infarcts. Such diffuse brain damage is an indication for duplex sonography or angiography, as well as echocardiography for the exclusion of atrial thrombosis.

If you suspect a stroke, it may take up to 30 hours for the swelling to appear clearly in the form of a zone of reduced density, different from unchanged brain tissue. Therefore, CT scan should be repeated if the initial scan did not show any pathological changes even if the patient had neurologic symptoms and these symptoms did not stop. The relief of symptoms indicates a transient ischemic attack (TIA) - in this case, with CT there are no visible changes.

In contrast to TIA with prolonged reversible ischemic neurologic deficit, CT zones are often defined as zones of edema of reduced density.

If the infarction zone corresponds to the area of the blood supply to the cerebral artery, one should think about the occlusion of the corresponding blood vessel. A classic infarct of the branches of the middle cerebral artery is manifested by a zone of ischemic edema of reduced density.

Depending on the extent of the lesion, a heart attack can cause a pronounced mass effect and cause a displacement of the midline. Infarctions of small size usually do not cause a displacement of the median line. If the integrity of the arterial wall is violated, bleeding may occur, which manifests itself in areas of increased density that cover the nearest gyrus.

[53], [54], [55], [56], [57], [58], [59], [60], [61]

Computer tomography in tumors and metastases

Although differential diagnosis of cerebral infarction and intracranial hemorrhages can be performed without the use of contrast agent, detection of brain metastases is significantly improved with the / in the use of contrast agents. At the same time, even the smallest zones of the BBB violation are visible. In images without contrast enhancement, large metastases of the same density (isodens) with surrounding tissues are sometimes accompanied by perifocal edema (and may be misinterpreted as swelling of tissues due to infarction.

After the introduction of a contrast agent, a differential diagnosis of the brain tumor is much easier.

[62], [63], [64], [65], [66], [67], [68], [69], [70], [71], [72], [73], [74], [75], [76]

Computer tomography in inflammatory processes

Another example of the advantage of using a contrast medium is the diagnosis of inflammatory processes, since this pathology is accompanied by a violation of the BBB and is not always clearly visible without amplification. Contrast enhancement confirms the presence of an inflammatory process. Bacterial infection of the aortic valve caused a septic embolism of the left occipital lobe.

Inflammation of the paranasal sinuses and middle ear can always be diagnosed on usual sections by the presence of effusion, for example, in the cells of the mastoid process, which are normally filled with air. The edema of the mucosa of the external auditory canal is clearly visualized without the introduction of a contrast agent. With the progression of the process and the formation of an abscess, it is necessary to examine the images in the bone window to search for sites of possible erosion of the surrounding bone formations.

The retention cyst, which is often identified in one of the paranasal sinuses, should be differentiated with inflammatory changes. It is characterized by a wide base on the sinus wall, spreading into its lumen and a rounded upper contour. Cysts are of clinical importance only if they cause obstruction of the funnel of the maxillary sinus or the semilunar canal, which leads to accumulation of a secret in the sinus.

In patients with chronic sinusitis, it is important to ensure that the lumen of the lunate canal is not obstructed, and there are no other restrictions to move the secretion of the ciliated epithelium. The most vulnerable structures in this respect are the Heller cells, the central nasal shell and the hooked process. Changes in these structures can lead to obstruction of the semilunar canal and cause chronic recurrent sinusitis.

[77], [78], [79], [80], [81], [82], [83], [84], [85], [86], [87]

Glaznitsy

Any education inside the orbit should be quickly diagnosed and effectively cured, otherwise severe consequences for vision are possible. To exclude the invasion of the tumor into the orbit wall, it is necessary to use a bone window.

Endocrine ophthalmopathy

When viewing CT images, the minimum changes can be skipped. Endocrine ophthalmopathy often manifests itself as a sign of Graves' disease (diffuse thyrotoxic goiter) and in the early stage can be diagnosed on the basis of thickening of the eye muscles, especially the lower rectus muscle. In the differential-diagnostic plan, one should bear in mind myositis.

If this early sign of endocrine ophthalmopathy, which is of an autoimmune nature, is missed, in the absence of adequate therapy, the damage to orbital tissues will progress.

The lesion pattern changes as the disease progresses. First, an increase in the volume of the lower rectus muscle is determined. Then, the internal rectus muscle and the upper rectus muscle react. The last increase in the muscles of the eye. Therefore, when analyzing CT images of the eye sockets, you should always control the symmetry of the muscles surrounding the eyes.

[88], [89], [90], [91], [92], [93], [94], [95], [96], [97], [98], [99], [100], [101], [102], [103], [104]

Facial skull bones and paranasal sinuses

Unlike retention cysts, malignant neoplasms of the paranasal sinuses often cause contact destruction of the bones of the facial skull and can spread to the orbit, the nasal cavity or even the anterior cranial fossa. Therefore, the sections should be viewed both in the soft-tissue and in the bone window. To plan an operation to remove volumetric neoplasm it is usually necessary to obtain CT sections in several projections. The following example demonstrates such a tumor of the paranasal sinuses in the axial and coronal projections. Starting with the mucosa of the right maxillary sinus, the tumor extends to the nasal cavity and the cell of the latticed bone.

In addition to determining the prevalence of chronic sinusitis, the main reason for performing scans in the coronal projection is the diagnosis of fractures. Fractures of the lower orbital wall are often accompanied by a dislocation of the cellulose or lower rectus muscle into the fracture region, or even into the inferior maxillary sinus. It is necessary to establish this before surgery. It is also important to detect indirect signs of fracture, such as a small gradation of bone contours and post-traumatic bleeding into the nasal cavity or frontal and maxillary sinuses. It is also important to establish whether there is a fracture of the head of the lower jaw? Is there a violation of the integrity of the bones of the upper jaw with a displacement of fragments from the sphenoid bone?

[105], [106], [107], [108], [109], [110], [111]

Fractures of the bones of the facial skeleton according to Le Fort

• Type I The fracture line passes through the upper jaw and maxillary sinus.
• Type II The fracture line passes through the zygomatic process of the upper jaw, inside the orbit to the frontal process of the upper jaw, where it passes to the opposite side. The maxillary sinus is not involved in the process.
• Type III The fracture line passes through the outer wall of the orbit and the frontal process of the upper jaw to the opposite side, involving the cells of the latticed bone, the malar bone and often with the transition to the base of the skull.