X-ray of the spine and spinal cord

The spine consists of 24 vertebrae, sacrum and coccyx. In healthy people, it forms characteristic physiological curves: anteriorly in the cervical and lumbar regions and posteriorly in the thoracic and sacral regions. The size of the vertebral bodies gradually increases in the caudal direction, i.e. Down. The vertebral body on radiographs has the shape of a rectangle with somewhat concave lateral edges and rounded corners. Adjacent horizontal platforms of the vertebral bodies form a clear wide contour on the roentgenograms (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 nucleus pulposus, located mainly in its central and posterior parts, a fibrous ring formed by fibrocartilaginous and collagen fibers along the periphery, 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 edging (limb) of the vertebra. The boundaries of the intervertebral disc roughly 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 over the limbus of each vertebra, but spreads over the intervertebral discs. The thin posterior longitudinal ligament covers the posterior surface of the vertebral bodies, attaching to the discs and lining the anterior wall of the spinal canal.

Radiation anatomy of the spine and spinal cord

On radiographs of the spine, arcs and processes of the vertebral bodies are clearly visible. In the picture in direct projection, the spinous processes are projected against the background of the vertebral bodies. The line connecting them, as it were, divides 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). An image of the roots of the arches and intervertebral joints is superimposed on the lateral parts of the bodies.

The images of the walls of the spinal canal, the walls of the canals of the nerve roots and the spinal cord with its membranes, as well as a number of intervertebral ligaments are obtained using CT. On tomograms, the vertebral bodies, their processes, intervertebral joints, lateral depressions of the spinal canal, in which the anterior and posterior nerve roots are located, are differentiated. Additional opportunities are opened by MRI, since it allows you to directly study the structure of the intervertebral disc and obtain an image of the substance of the spinal cord in all projections. Three-dimensional reconstruction of ray 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 X-ray or CT is performed. This combination, especially the combination of tomography and myelography (contrasting of the subarachnoid space), provides a detailed examination of the surface of the spinal cord with the measurement of its diameter in different parts, the volume and configuration of the dural sac, nerve roots that go into the intervertebral foramen in the sheaths.

With flexion and extension, the relationship between the vertebrae changes, which is clearly visible on radiographs. In particular, during flexion, the anterior part of the intervertebral disc narrows and its posterior part expands. The set of two adjacent vertebrae and the disc connecting them is usually called the motor segment of the spine. Pictures in different positions of the spinal column (the so-called functional radiography) make it possible to detect both blockade of the motor segment and its instability, i.e. Abnormal displacement of one vertebra relative to the adjacent one.

 

Spine and spinal cord injuries

Radiation examination of the spine in victims is performed as directed by a surgeon or neuropathologist (neurosurgeon). In case of acute trauma, preparation of the patient for examination is not required, but the basic principle of transportation must be observed: horizontal position and straightened body of the victim. The study, as a rule, is carried out in the position in which he was delivered to the X-ray room.

For a long time, X-ray in two projections was considered the main method of detecting a spinal injury. It is with her that it is advisable to start research. Conventional images allow us to assess the deformity 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 gained particular importance. In spinal trauma, CT has a number of distinct advantages. First of all, it is easy to perform it in a horizontal position of the victim without any manipulation with him. However, the main thing is that CT provides 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 state 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 the analysis of radiographs is to establish the shape of the spinal column. In the event of damage to the vertebrae and the surrounding ligaments and muscles, traumatic deformity of the spine occurs, normal physiological bends are smoothed or eliminated, and the line drawn along the contour of the posterior surface of the vertebral bodies and normally forming a flat, even arc is straightened or bent at the level of damage. An important way to identify traumatic injuries of 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 - the displacement of the vertebrae by more than 1-2 mm (which is observed in the norm).

The second task is to identify the violation of the integrity of the vertebral bodies, their arcs or processes. Depending on the mechanism of injury, various fractures occur, but the overwhelming majority of them belong to the so-called compression fractures. With them, a wedge-shaped deformity of the vertebral body is determined, especially in a lateral picture; the top of the wedge is facing anteriorly; 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; around the damaged vertebra, a semi-oval shadow with arcuate outer contours can be seen in the images - an image of a paravertebral hematoma. It is necessary to check with particular attention the outlines of the spinal canal at the level of the broken vertebra: whether there has been a narrowing of this canal. In addition, it is necessary to carefully examine the contours of the arches and processes of the vertebrae so as 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 imaging is a reliable diagnostic tool, it still more fully reveals the picture of CT damage. Fractures of bodies, arches and processes and, most importantly, the condition of the walls of the spinal canal are more clearly distinguished on tomograms. Traumatic hernias of intervertebral discs, hematomas in the epidural and subarachnoid spaces, and displacement of the spinal cord are clearly visible. For more accurate detection of spinal cord injury, CT is performed in combination with the introduction of a contrast agent into the subarachnoid space, i.e. With myelography. On MRI, spinal cord injury and intramedullary hemorrhage are recognized without myelography. MRI provides detection of traumatic disc herniation and epidural hematoma, i.e. Damage, for the elimination of which surgical intervention is necessary. In the rehabilitation period, a post-traumatic cyst usually occurs at the site of intracerebral hemorrhage, and it is also found on MRI.

 

Vertebral pain syndrome

A 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 the compression is caused by central or lateral stenosis of the spinal canal. A narrow spinal canal as an individual variant of development may 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. Suffice it to note that only in the cervical spine, in addition to 7 vertebrae, there are 25 synovial and 6 fibrocartilaginous joints and numerous ligamentous structures. Overload of 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 subluxation (unstable phase), in the discs - in a violation of their function and a decrease in height, instability in the motor segment. Already these changes lead to dynamic stenosis of the spinal canal, i.e. To stenosis that occurs when the vertebrae are flexed, extended, or rotated. In particular, the superior articular process exerts pressure on the nerve root.

In the future, the stabilization phase begins, which is characterized by more or less persistent organic stenosis of the spinal canal. In the intervertebral joints, its occurrence is due to an increase in articular processes and the formation of osteophytes, especially on the lower articular processes. Cartilaginous hernias are often the cause of stenosis. A hernia is a posterior protrusion of a part of the disc, which affects the 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 disc herniation:

1. local protrusion - the nucleus pulposus of the disc is flattened, as a result of which the annulus fibrosus slightly bulges into the lumen of the spinal canal;
2. protrusion - a more significant flattening of the nucleus pulposus, which still remains inside the annulus fibrosus, while there is a more significant protrusion of the disc into the lumen of the spinal canal;
3. prolapse, or extruded disc, - the nucleus pulposus penetrates the fibrous disc, but is located inside the posterior longitudinal ligament. Disk fragmentation is distinguished separately, i.e. Detachment of its piece and the formation of a free fragment (sequestration).

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

CT and MRI have become the main methods of diagnosing pain syndrome, more precisely, establishing its nature. Measuring the spinal canal, determining the degree and type of its deformity, identifying calcifications, hypertrophy of the ligaments, cartilaginous hernias, arthrosis of the intervertebral joints, tumors in the spinal canal, assessing the state of the spinal cord - this is not a complete list of the possibilities of radiation methods.

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

In cases where the patient complains of pain in the spine, and no pathological changes have been detected during neurological and radiological examinations, it is always appropriate, especially in the elderly, to perform bone scintigraphy, since metastases of a clinically non-manifesting tumor in the vertebrae are usually seen on scintigrams much earlier than on radiographs. Thus, the tactics of radiation research in vertebrogenic pain syndrome should be selected based on the capabilities of radiation methods.

The bulk of those who go to the doctor for pain in the spine are patients with dystrophic lesions. Every clinician, regardless of his specialization, should have a general understanding of them. Spinal dystrophic lesions 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 between 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 failure, which can initially be determined by functional radiographs. With flexion, extension, or rotational movements in the spine, either blockade or instability of the affected motor segment is determined. This means that in functional images either the relationship between two adjacent vertebrae does not change at all, or, on the contrary, their increased mobility arises up to the sliding of one of the vertebrae in relation to the other. This slipping is called pseudospondylolisthesis, i.e. False slipping. The fact is that there is an anomaly in the development of the spine, in which there is a gap (defect) in the inter-articular arch of the vertebra, as a result of which sliding of the vertebra anteriorly can develop, i.e. Spondylolisthesis.

Another sign of osteochondrosis, directly related to the degeneration of the intervertebral disc, is a decrease in its height. The end plates of the vertebral bodies thicken, and the spongy bone tissue underlying them becomes sclerosed (subchondral sclerosis). The disc cannot fully fulfill its function. As compensation, bone growths occur 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. Are a continuation of the horizontal platforms of the vertebral bodies.

Through the breaks in the fibers of the annulus fibrosus, cartilage can protrude to the side - this is how cartilaginous hernias are formed. Localization distinguishes between central, posterolateral, lateral foraminal and lateral extraforaminal disc herniation. Sometimes the cartilaginous mass penetrates into the spongy tissue of the vertebral body, where it is surrounded by the rim of sclerosis. Such a hernia by the name of the scientist who studied it was called Schmorl's hernia. However, it is mainly the posterior and posterolateral hernias that are clinically significant, since they entail compression of the nerve roots, the meninges of the spinal cord, and brain tissue. It has already been noted above that these hernias are recognized by CT, MRI and myelography.

Under the control of CT, percutaneous interventions are performed: biopsy of the intervertebral disc, discectomy, chemonucleolysis (introduction of the enzyme chymopain into the nucleus of the disc). 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 investigated section is taken. This x-ray examination is called discography.

Spondylosis deformans is an adaptive condition that develops when the peripheral layers of the annulus fibrosus are affected. In this condition, the height of the intervertebral disc almost or does not decrease at all, subchondral sclerosis is not observed, but on the roentgenogram, bone bridges appear from the body of the overlying vertebra to the body of the underlying vertebra, i.e. Located along the longitudinal axis of the spine. These bone bridges are formed as a result of degeneration and ossification of the anterior longitudinal ligament and paravertebral tissues.

Arthrosis in the intervertebral joints is essentially no different from deforming osteoarthritis in any joint. It is characterized by a 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 (recessions) of the spinal canal and compression of the nerve roots.

Ankylosing hyperostosis (fixing ligamentosis, Forestier disease) resembles deforming spondylosis in a number of ways. With it, bone formation also occurs under the anterior longitudinal ligament and in the prevertebral tissues, but it spreads over a considerable extent, usually covering the entire or almost the entire thoracic spine. The diagnosis of calcification of the intervertebral disc does not cause any difficulties: lime deposits in it are demonstratively looming on the images and tomograms. Due to the razvlecheniya and drying of the disk, sometimes cracks are formed in it, filled not with lime, but with gas, which are also clearly distinguished on X-ray diffraction patterns and CT scans. This symptom of a dystrophic condition of cartilage is usually called a vacuum phenomenon. It occurs when not only the intervertebral discs are damaged, but also other joints, such as the knee.

 

Inflammatory diseases of the spine

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

Of the radiation methods of research, the main one is a survey radiography of the spine in two projections - frontal 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 state of the end plates of the vertebral bodies and the intervertebral disc. The first signs of septic spondylitis are erosion, destruction, subchondral sclerosis and rarefaction of the end plates. In the future, the process moves to the intervertebral discs, which are noticeably narrowed. In septic spondylitis, a decrease in the height of the disc comes to the fore, and only then marginal bone changes are revealed. It should be noted that, despite the importance of X-ray 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 the diagnosis of spondylitis. The data obtained with it are useful only in the advanced stage of the disease, when a zone of heterogeneous destruction and sclerosis is revealed on tomograms in the body of the affected vertebra. With this method, paravertebral and epidural abscesses can be identified that are not visible on plain radiographs. When spondylitis is cured, osteosclerosis, a significant narrowing of the intervertebral space, or even bone ankylosis are found on radiographs and computed tomograms.

A more valuable method in the diagnosis of spondylitis is MRI. With its help, pathological changes in the intervertebral discs, bone marrow, paravertebral tissues are detected very early. On T1-weighted MRI tomograms, areas of purulent fusion of bone tissue are displayed in the form of hypodense foci, and on T2-weighted tomograms - as zones of increased intensity.

Spine scintigraphy with 99mTc pyrophosphate is highly sensitive. Scintigrams reveal a zone of hyperfixation early enough 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: according to its results, it is impossible to determine what specific disease a given patient has.

In tuberculous spondylitis, the most common manifestation of osteoarticular tuberculosis, plain radiographs show areas of subchondral erosion and destruction in the end plates of the vertebral bodies. In the case of a lesion of the thoracic spine, these changes are maximally manifested in the anterior parts of the vertebral bodies, which further leads to their compression and the formation of a hump. In the lumbar vertebrae, the destruction of the vertebral bodies often occurs in the middle sections, and then axial compression occurs. The general radiological background of tuberculous spondylitis, as well as tuberculosis lesions of the skeleton in general, is an increase in the transparency of bone tissue on radiographs. This increase in transparency is a sign of osteopenia - a kind of bone loss.

The narrowing of the intervertebral discs occurs much later than with a purulent process (this, by the way, facilitates the differential diagnosis of these diseases). Paravertebral abscesses are a characteristic feature of tuberculous spondylitis. 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, often tuberculous abscesses spread over considerable distances: they penetrate the psoas muscle, subpleural spaces, inside the chest, 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 for diagnosing tuberculous spondylitis is X-ray - plain radiographs and linear tomography. More clearly, all of the above changes are recognized by AT and MRI, which, nevertheless, with this disease are only of an auxiliary nature.

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

Non-tuberculous spondylitis causes, in general, the same changes on the X-ray, but the foci of destruction with them are often small, located in the corners of the vertebral bodies. The decrease in the height of the intervertebral disc occurs much faster than in 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. In tuberculous spondylitis, ossification of the ligaments occurs much later.

The pathological processes that often occur in the spine include metastases of malignant tumors in the bodies, arches and processes of the vertebrae. They are initially detected as image defects on MRI scans. With almost the same frequency, they can be detected as "hot" foci on osteoscintigrams. Then, the foci of destruction are determined on computed tomograms and radiographs of the spine.

 

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