X-ray signs of skull and brain damage

X-ray examinations of victims are carried out as prescribed by a surgeon, traumatologist or neurologist (neurosurgeon). The basis for such a prescription is a head injury, general cerebral (headache, nausea, vomiting, impaired consciousness) and focal neurological symptoms (speech disorders, sensitivity, motor sphere, etc.). The clinician's referral must necessarily indicate a presumptive diagnosis.

The severity of the injury is determined not so much by the violation of the integrity of the skull bones, but by damage to the brain and its membranes. In this regard, in the vast majority of cases, radiological examination in acute trauma should consist of CT. It is necessary to remember that in some cases the injury seems light and the radiographs do not even reveal a violation of the integrity of the bones, but due to ongoing intracranial bleeding, the patient's condition may significantly worsen in the following hours and days.

Conventional radiographs are indicated mainly for depressed fractures, when the fragments are mixed into the cranial cavity. They can also detect the mixing of calcified intracranial structures, normally located midline (pineal gland, falx), which is an indirect sign of intracranial hemorrhage. In addition, radiographs can sometimes reveal small linear fractures that escape the radiologist when analyzing CT. However, we repeat once again that the main radiation method of examination for head injuries is CT.

When performing a radiological examination on patients with skull and brain damage, the radiologist must answer three questions:

1. is there a violation of the integrity of the bones of the skull;
2. whether the fracture is accompanied by the penetration of fragments into the cranial cavity and damage to the eye sockets, paranasal sinuses and middle ear cavity;
3. is there damage to the brain and its membranes (edema, hemorrhage).

Among peacetime injuries, linear fractures (cracks) of the cranial vault bones predominate. In the vast majority of cases, they occur at the site of force application (this fact always makes it easier to detect a crack). A fracture is defined as a sharp, sometimes zigzag, sometimes bifurcating strip with slightly uneven edges. Depending on the nature of the injury, the position and length of the crack are very diverse. They can affect only one plate or both, and extend to the cranial suture, causing it to diverge.

In addition to cracks, there are perforated, depressed and comminuted fractures. In these, as noted above, it is especially important to establish the degree of displacement of fragments into the cranial cavity, which is easy to do with targeted images. Significant displacement of fragments is observed in fractures of gunshot origin. In blind wounds, it is necessary to determine the presence and exact localization of foreign bodies, in particular, to establish whether the bullet or fragment is in the cranial cavity or outside it.

Basal skull fractures are usually a continuation of the vault crack. Frontal bone cracks usually descend to the frontal sinus, the upper wall of the orbit, or the ethmoid labyrinth, parietal and temporal bone cracks - to the middle cranial fossa, and occipital bone cracks - to the posterior cranial fossa. When choosing an X-ray technique, clinical data are taken into account: bleeding from the nose, mouth, ears, cerebrospinal fluid leakage from the nose or ear, hemorrhage in the eyelid or soft tissues of the mastoid process, dysfunction of certain cranial nerves. According to clinical and X-ray signs, the doctor takes pictures of the anterior, middle, or posterior cranial fossa.

On computer tomograms, the area of fresh hemorrhage has increased density, its position, size and shape depend on the source and localization of bleeding. The density of the hematoma shadow increases in the first 3 days after injury and then gradually decreases over 1-2 weeks.

An intracerebral hematoma is usually well delimited; if it is large, it displaces adjacent brain structures (this effect is called the "mass effect"). There may be a zone of decreased density (hypotensive zone) around the hematoma. Its substrate is edematous brain tissue. If the hemorrhage penetrates into a ventricle of the brain, the area of increased density takes the shape of the corresponding section of the ventricle. Trauma may cause swelling of the brain tissue due to edema and hyperemia. In this case, a zone of increased density of a diffuse or focal nature is noted on CT. It is most clearly visible 12-24 hours after the injury.

Hemorrhage may occur under the dura mater or between it and the cranial bones. Fresh subdural and epidural hematomas also form on CT scans an area of increased and uniform density, elongated, often oval in shape, which is adjacent to the image of the cranial bones.

At the same time, hemorrhage into the brain tissue may be observed, and in the case of a large subdural hematoma, a mass effect. Subsequently, the density of the hematoma decreases and becomes even less than the density of the brain matter.

CT allows detecting hemorrhage into the paranasal sinuses or air penetration from these sinuses into the cranial cavity - pneumocephalus. Mass effect is also established by the displacement of midline structures during one-dimensional ultrasound examination.

The role of MRI in examining patients with skull fractures is very limited. Its main purpose is to monitor the state of the brain during treatment.

Brain contusions are common traumatic injuries that manifest as cerebral edema with or without hemorrhage. Sometimes a true hematoma may form with a contusion. The injuries are often multiple, with a significant portion of them occurring in the frontal and temporal lobes.

In CT, edematous tissue appears as a low-density area. The edema pattern in MRI depends on the imaging method: in T1-weighted tomograms, the edema area appears hypointense, in T2-weighted tomograms, hyperintense. Cerebral hemorrhage is detected in CT or MRI.