X-rays of the spine and spinal cord

The spine consists of 24 vertebrae, the sacrum and the coccyx. In healthy people, it forms characteristic physiological curves: forward in the cervical and lumbar regions and backward in the thoracic and sacral regions. The size of the vertebral bodies gradually increases in the caudal direction, i.e. downwards. On radiographs, the vertebral body has the shape of a rectangle with slightly concave lateral edges and rounded corners. Adjacent horizontal surfaces of the vertebral bodies form a clear wide contour on radiographs (the second contour is due to one of the edges of the vertebral body). In front, the vertebra rests on the intervertebral disc, and behind - on two intervertebral joints - a kind of three-joint complex.

The intervertebral disc consists of a gelatinous nucleus, located mainly in its central and posterior parts, a fibrous ring formed by fibrocartilaginous and, on the periphery, collagen fibers, and two thin hyaline plates, each of which - the upper and lower - tightly adjoins the horizontal platform of the corresponding vertebra. On the periphery, the hyaline plate is surrounded by the marginal bone edge (limbus) of the vertebra. The boundaries of the intervertebral disc approximately coincide with the edges of the horizontal platforms or protrude slightly beyond them.

The anterior and lateral surfaces of the spinal column are surrounded by the anterior longitudinal ligament. It attaches above the limbus of each vertebra but extends over the intervertebral discs. The thin posterior longitudinal ligament covers the back surface of the vertebral bodies, attaching to the discs and lining the anterior wall of the spinal canal.

Radial anatomy of the spine and spinal cord

The X-ray images of the spine clearly show the arches and processes of the vertebral bodies. In a direct projection image, the spinous processes are projected against the background of the vertebral bodies. The line connecting them seems to divide the vertebral bodies into two equal parts. The height of the right and left halves of the vertebra is normally the same (if there is no scoliosis). The image of the roots of the arches and intervertebral joints is superimposed on the lateral sections of the bodies.

The image of the walls of the spinal canal, the walls of the nerve root canals and the spinal cord with its membranes, as well as a number of intervertebral ligaments are obtained using CT. Tomograms differentiate the bodies of the vertebrae, their processes, intervertebral joints, lateral depressions of the spinal canal, in which the anterior and posterior nerve roots are located. MRI opens up additional possibilities, since it allows direct study of the structure of the intervertebral disc and obtaining an image of the spinal cord substance in all projections. Three-dimensional reconstruction of radiation images of the spinal column has also become possible.

In order to contrast the subarachnoid, subdural and epidural spaces, a radiopaque substance is injected into them, after which radiography or CT is performed. Such a combination, especially a combination of tomography and myelography (contrasting the subarachnoid space), provides a detailed examination of the surface of the spinal cord with measurement of its diameter in different sections, the volume and configuration of the dural sac, nerve roots leaving in the meningeal sheaths into the intervertebral openings.

When bending and unbending, the relationship between the vertebrae changes, which is clearly visible on X-rays. In particular, when bending, the anterior part of the intervertebral disc narrows and its posterior part expands. The combination of two adjacent vertebrae and the disc connecting them is usually called the motor segment of the spine. Images in different positions of the spinal column (the so-called functional radiography) allow us to detect both a blockade of the motor segment and its instability, i.e. abnormal displacement of one vertebra relative to the neighboring one.

Spinal cord and spinal cord injuries

Radiation examination of the spine of victims is performed as prescribed by a surgeon or neurologist (neurosurgeon). In case of acute trauma, no preparation of the patient for the examination is required, but it is necessary to observe the basic principle of transportation: horizontal position and straightened body of the victim. The examination is usually performed in the position in which he was delivered to the X-ray room.

Since ancient times, the main method for detecting spinal trauma has been considered to be radiography in two projections. It is with this that it is advisable to begin the examination. Conventional images allow you to assess the deformation of the spine, detect fractures, subluxations and dislocations of the bodies and processes of the vertebrae, and clarify the level of damage.

In recent years, CT and MRI have become especially important. In spinal trauma, CT has a number of undoubted advantages. First of all, it is easy to perform in a horizontal position of the victim without any manipulations with him. However, the main thing is that CT provides for the study of the walls of the spinal canal, intra- and paraspinal tissues, and the severity and prognosis of damage to this area are primarily determined by the condition of the spinal cord, its membranes and nerve roots. MRI makes it possible to obtain an image of the spinal cord along its entire length in different projections.

The first task in analyzing radiographs is to establish the shape of the spinal column. In case of damage to the vertebrae and surrounding ligaments and muscles, traumatic deformation of the spine occurs, normal physiological curves are smoothed out or eliminated, and the line drawn along the contour of the back surface of the vertebral bodies, which normally forms a flat, even arc, straightens out or bends at the level of damage. An important method for detecting traumatic damage to the ligamentous apparatus of the spine is functional radiography - obtaining radiographs in the phases of maximum flexion and extension. This study reveals an important symptom of instability - displacement of the vertebrae by more than 1-2 mm (which is observed normally).

The second task is to detect the violation of the integrity of the vertebral bodies, their arches or processes. Depending on the mechanism of injury, various fractures occur, but the overwhelming majority of them are so-called compression fractures. In them, a wedge-shaped deformation of the vertebral body is determined, especially on the lateral image; the apex of the wedge is facing forward; mainly the upper part of the vertebral body is flattened; a change in topographic-anatomical conditions is expressed in angular kyphosis and subluxation in the intervertebral joints; a semi-oval shadow with arcuate outer contours may be noticeable in the images around the damaged vertebra - an image of a paravertebral hematoma. It is necessary to check the outlines of the spinal canal at the level of the broken vertebra with special attention: has this canal narrowed? In addition, it is necessary to carefully examine the contours of the arches and processes of the vertebrae in order not to miss their fracture, as well as dislocation in the intervertebral joints, and in case of gunshot wounds - the localization of foreign bodies.

Although conventional images are a reliable diagnostic tool, CT scans provide a more complete picture of the damage. Tomograms more clearly highlight fractures of the bodies, arches and processes and, most importantly, the condition of the walls of the spinal canal. Traumatic herniated discs, hematomas in the epidural and subarachnoid spaces, and spinal cord displacements are clearly visible. For more accurate detection of spinal cord damage, CT scans are performed in combination with the introduction of a contrast agent into the subarachnoid space, i.e. with myelography. With MRI, spinal cord damage and intramedullary hemorrhage are recognized even without myelography. MRI provides detection of traumatic disc herniation and epidural hematoma, i.e. damage that requires surgical intervention to eliminate. During the rehabilitation period, a post-traumatic cyst usually develops at the site of intracerebral hemorrhage, and it is also detected with MRI.

Vertebrogenic pain syndrome

The common cause of pain in any part of the spine - cervical, thoracic, lumbar or sacral - is compression of the spinal cord, its membranes and the roots of the nerves extending from it, and compression is caused by central or lateral stenosis of the spinal canal. A narrow spinal canal as an individual developmental variant can be a predisposing factor.

The frequent occurrence of vertebrogenic pain syndrome is explained by the complexity of the anatomical structure of the spine and the importance of its function. It is enough to note that in the cervical spine alone, in addition to 7 vertebrae, there are 25 synovial and 6 fibrocartilaginous joints and numerous ligamentous structures. Overloading the spine, poor development of the muscles of the neck and back, many pathological processes lead to degenerative-dystrophic changes in the intervertebral discs and joints. In the joints, they are initially expressed in synovitis, and then in subluxations (unstable phase), in the discs - in the disruption of their function and a decrease in height, instability in the motor segment. These changes already lead to dynamic stenosis of the spinal canal, i.e. to stenosis that occurs during flexion, extension or rotation of the vertebrae. In particular, the superior articular process puts pressure on the nerve root.

Subsequently, the stabilization phase occurs, which is characterized by more or less persistent organic stenosis of the spinal canal. In the intervertebral joints, its occurrence is due to the enlargement of the articular processes and the formation of osteophytes, especially on the lower articular processes. Stenosis is often caused by cartilaginous hernias. A hernia is a protrusion of part of the disc backwards, which entails central stenosis of the spinal canal, or to the side, which leads to lateral stenosis and narrowing of the canal in which the nerve root is located. There are three degrees of severity of a disc herniation:

1. local protrusion - the gelatinous nucleus of the disc is flattened, as a result of which the fibrous ring slightly bulges into the lumen of the spinal canal;
2. protrusion - a more significant flattening of the gelatinous nucleus, which still remains inside the fibrous ring, while a more significant bulging of the disc into the lumen of the spinal canal is noted;
3. prolapse, or extruded disc - the gelatinous nucleus penetrates the fibrous disc, but is located inside the posterior longitudinal ligament. Disc fragmentation is distinguished separately, i.e., the tearing off of a piece of it and the formation of a free fragment (sequestrum).

Recognition and differential diagnostics of diseases that cause vertebrogenic pain syndrome are most often carried out using radiation methods. The initial method is a survey radiography of the spine. It allows you to determine the configuration of the spinal column, establish the presence and nature of the lesion, and outline the level of research for CT and MRI.

CT and MRI have become the main methods of diagnosing pain syndrome, or more precisely, establishing its nature. Measuring the spinal canal, determining the degree and type of its deformation, identifying calcifications, ligament hypertrophy, cartilaginous hernias, arthrosis of the intervertebral joints, tumors in the spinal canal, assessing the condition of the spinal cord - this is far from a complete list of the capabilities of radiation methods.

In combination with myelography, CT allows differentiation of subarachnoid space deformations in hernias, extradural, intradural and intramedullary tumors, meningocele, vascular deformations, etc. It is clear how important CT results are when planning surgical treatment. Similar information is obtained with MRI, and its value is especially great in cervical radiculopathy, since the spinal cord, disc herniations, osteophytes are clearly visible on the tomogram.

In cases where the patient complains of pain in the spine, and pathological changes are not revealed by neurological and radiological examinations, it is always appropriate, especially in elderly people, to perform osteoscintigraphy, since metastases of a clinically silent tumor in the vertebrae are usually visible on scintigrams much earlier than on radiographs. Thus, the tactics of radiation examination for vertebrogenic pain syndrome should be chosen based on the capabilities of radiation methods.

The majority of people who seek medical attention for back pain are patients with degenerative lesions. Every clinician, regardless of their specialization, should have a general idea of them. Degenerative lesions of the spine are complex lesions that affect all bones, joints, and soft tissues of the spinal column. Depending on the predominant component, it is advisable to distinguish five types of lesions: osteochondrosis, deforming spondylosis, intervertebral arthrosis, ankylosing hyperostosis (fixing ligamentosis), and disc calcification.

Dystrophic changes in the intervertebral disc lead to its functional insufficiency, which can initially be determined by functional radiographs. During flexion, extension or rotational movements in the spine, either a block or instability of the affected motion segment is determined. This means that on functional images either the relationship between two adjacent vertebrae does not change at all, or, on the contrary, there is increased mobility up to the slippage of one of the vertebrae relative to the other. Such slippage is called pseudospondylolisthesis, i.e. false slippage. The fact is that there is an anomaly in the development of the spine, in which there is a gap (defect) in the interarticular section of the vertebral arch, as a result of which a slippage of the vertebra forward may develop, i.e. spondylolisthesis.

Another sign of osteochondrosis, directly related to the degeneration of the intervertebral disc, is a decrease in its height. The endplates of the vertebral bodies thicken, and the underlying spongy bone tissue becomes sclerotic (subchondral sclerosis). The disc cannot fully perform its function. As compensation, bone growths appear along the edges of the vertebral bodies, as a result of which the articular surface increases. These growths are mainly directed perpendicular to the longitudinal axis of the spine, i.e. they are a continuation of the horizontal surfaces of the vertebral bodies.

Through the ruptures in the fibers of the fibrous ring, the cartilage can protrude to the side - this is how cartilaginous hernias are formed. According to localization, there are central, posterolateral, lateral foraminal and lateral extraforaminal disc herniations. Sometimes the cartilaginous mass penetrates into the spongy tissue of the vertebral body, where it is surrounded by a rim of sclerosis. Such a hernia was called a Schmorl's hernia after the scientist who studied it. However, clinically significant are mainly posterior and posterolateral hernias, since they entail compression of the nerve roots, spinal cord membranes and brain tissue. It was already noted above that these hernias are recognized by CT, MRI and myelography.

Under CT control, percutaneous interventional procedures are performed: intervertebral disc biopsy, discectomy, chemonucleolysis (introduction of the enzyme chymopain into the disc nucleus). In some cases, to clarify the details of structural lesions of the disc, a contrast agent is injected into it by puncture, and then an X-ray of the examined section is performed. Such an X-ray examination is called discography.

Deforming spondylosis is an adaptive condition that develops when the peripheral layers of the fibrous ring of the disc are affected. In this condition, the height of the intervertebral disc is almost or not at all reduced, subchondral sclerosis is not observed, but bone bridges from the body of the overlying vertebra to the body of the underlying one, i.e. located along the longitudinal axis of the spine, are visible on the radiograph. These bone bridges are formed due to degeneration and ossification of the anterior longitudinal ligament and paravertebral tissues.

Arthrosis in the intervertebral joints is essentially no different from deforming osteoarthrosis in any joint. It is characterized by narrowing of the joint space, thickening of the closing bone plates of the epiphyses, subchondral sclerosis and the appearance of marginal bone growths - osteophytes, which can lead to narrowing of the lateral pockets (recesses) of the spinal canal and compression of the nerve roots.

Ankylosing hyperostosis (fixing ligamentosis, Forestier's disease) resembles deforming spondylosis in a number of features. It also involves bone formation under the anterior longitudinal ligament and in the prevertebral tissues, but it extends over a significant area, usually covering the entire or almost entire thoracic spine. Diagnosis of intervertebral disc calcification is not difficult: lime deposits in it are clearly visible on images and tomograms. Due to the fraying and drying of the disc, cracks sometimes form in it, filled not with lime, but with gas, which are also clearly visible on X-rays and CT. This symptom of a dystrophic condition of cartilage is usually called a vacuum phenomenon. It occurs when not only intervertebral discs are affected, but also other joints, such as the knee.

Inflammatory diseases of the spine

The causes of inflammatory diseases of the spine can be bacteria, mycobacteria tuberculosis, fungi, parasites. Aseptic spondylitis is rarely observed, for example, in rheumatoid arthritis or deforming spondylitis. Timely diagnosis of all these diseases is extremely important, as it allows for timely adequate conservative or surgical treatment.

Of the radiation methods of examination, the main one is a survey radiography of the spine in two projections - direct and lateral. In this case, special attention should be paid to the analysis of the structure of the bone pattern of the vertebral body, the condition of the end plates of the vertebral bodies and the intervertebral disc. The first signs of septic spondylitis are erosions, destruction, subchondral sclerosis and rarefaction of the end plates. Later, the process moves to the intervertebral discs, which noticeably narrow. In septic spondylitis, a decrease in the height of the disc comes to the fore, and only then are marginal bone changes revealed. It should be noted that, despite the importance of radiological examination of the spine in septic spondylitis, the signs of the disease detected in this case lag behind its clinical manifestations, sometimes by 2-3 weeks.

CT plays a very modest role in diagnosing spondylitis. The data obtained with it are useful only in the advanced stage of the disease, when the tomograms in the body of the affected vertebra reveal a zone of heterogeneous destruction and sclerosis. With the help of this method, paravertebral and epidural abscesses that are not visible on plain radiographs can be detected. When spondylitis is cured, osteosclerosis, significant narrowing of the intervertebral space, or even bone ankylosis are detected on radiographs and CT scans.

A more valuable method in diagnosing spondylitis is MRI. It helps to detect pathological changes in intervertebral discs, bone marrow, and paravertebral tissues very early. On T1-weighted MRI tomograms, areas of purulent bone tissue melting are displayed as hypodense foci, and on T2-weighted tomograms - as zones of increased intensity.

Scintigraphy of the spine with 99mTc-pyrophosphate is characterized by high sensitivity. Scintigrams reveal hyperfixation zones quite early in septic and aseptic osteomyelitis, discitis, tumors, degenerative processes, as well as in places of traumatic and osteoporotic fractures. However, this study has extremely low specificity: its results cannot be used to determine what specific disease a given patient has.

In tuberculous spondylitis, the most common manifestation of osteoarticular tuberculosis, plain radiographs reveal areas of subchondral erosion and destruction in the endplates of the vertebral bodies. In the case of damage to the thoracic spine, these changes are most pronounced in the anterior parts of the vertebral bodies, which subsequently leads to their compression and the formation of a hump. In the lumbar vertebrae, destruction of the vertebral bodies often occurs in the middle parts, and then axial compression occurs. The general radiographic background of tuberculous spondylitis, as well as tuberculous skeletal lesions in general, is an increase in the transparency of bone tissue on radiographs. Such increased transparency is a sign of osteopenia, a specific form of rarefaction of bone tissue.

Narrowing of the intervertebral discs occurs much later than in the case of a purulent process (this, by the way, facilitates differential diagnostics of the above diseases). A characteristic sign of tuberculous spondylitis is paravertebral abscesses. An abscess usually looks like an intense biconvex shadow, the maximum diameter of which corresponds to the diameter of the affected segment of the spine. However, tuberculous abscesses often spread over significant distances: they penetrate the lumbar muscle, subpleural spaces, into the chest, into the groin and even descend into the popliteal fossa. In some cases, these abscesses contain lime, and then their recognition on radiographs is easier. The main method of diagnosing tuberculous spondylitis is radiological - overview radiographs and linear tomography. All the above changes are more clearly recognized by AT and MRI, which, however, are only auxiliary in this disease.

Thus, the main symptoms of tuberculous spondylitis are destructive changes in the vertebrae, destruction of intervertebral discs, perifocal or abscesses, osteoporosis.

Non-tuberculous spondylitis causes generally the same changes on the X-ray image, but the foci of destruction are often small, located in the area of the angles of the vertebral bodies. The decrease in the height of the intervertebral disc occurs much faster than with tuberculous lesions, and reparative changes are determined almost as quickly: lime deposits appear in the anterior longitudinal ligament in the form of brackets between the bodies of the affected vertebrae. With tuberculous spondylitis, ossification of the ligaments occurs much later.

Among the pathological processes that frequently occur in the spine are metastases of malignant tumors in the bodies, arches, and processes of the vertebrae. Initially, they are detected as image defects on MRI tomograms. Almost with the same frequency, they can be detected as "hot" foci on osteoscintigrams. Then, the foci of destruction are determined on computer tomograms and X-rays of the spine.

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