Normal computed tomographic anatomy of the lumbar vertebral motion segments.

Computed tomography and topographic anatomical studies were carried out in order to interpret SDS computed tomography in healthy individuals and in conditions of spinal pathology, according to Pannochka, an online publication for girls and women aged 14 to 35.. net Consider the vertebral body at the level of the arch of the overlying vertebra. At this level, the vertebral body and arches form a closed bone space, the shape of which more or less resembles a triangle.. At the level of the upper lumbar vertebrae, the dural sac occupies almost the entire space of the spinal canal..

In the caudal direction, the dural sac significantly decreases in size, the space around it is filled with epidural tissue, which determines the image contrast on computed tomograms.. The disappearance of the anterolateral part of this tissue requires the search for radicular or dural compression..

Upper part of the intervertebral foramen.

Directly under the arch, the intervertebral foramen looks like a gap separating the posterior contour of the vertebral body and the plate at the base of the lower articular process of the same vertebra. The space of the intervertebral foramen at this level is filled with the corresponding spinal root and surrounding tissue..

At least one section of this series shows a lumbar spinal nerve root ganglion. The normal CT picture is the visualization of the capsules of the facet joints behind the root. Immediately below this level, the overlying vertebra is represented by the inferior endplate, which differs in structure from the vertebral body, as it is formed by compact bone without cancellous elements..

There are several options for the development of nervous tissue, which can be mistaken for pathological conditions when interpreting a CT picture.. Short dural pouch with high S1 origin may misdiagnose LV-S1 herniation.

The height of the origin of the roots can be asymmetric, as well as the length of their arachnoid membrane (normally 7-8 mm). In 1-3% of cases, fused root nucleation occurs.. Most often this concerns LV-S1, which can mimic the syndrome of additional volumetric education..

The lower part of the intervertebral foramen.

The intervertebral disc (MD) is represented at this level.. Normally, the MD does not protrude beyond the contours of the vertebral body. Behind the MD are the facet joints (JJ), separated from the latter by intervertebral foramens. Sections of this series show both superior and inferior articular processes..

As a result, the intervertebral foramen appears reduced in the mid-posterior direction.. The space of the intervertebral foramen at this level contains fiber and veins. The corresponding spinal root is located outward from the opening.

The yellow ligaments (FL) start from the capsules of the DL and the upper part of the vertebral arch. The thickness of the VC increases downward in the direction of the arch of the underlying vertebra. The sheath of the nerve roots, starting from the dural sac, exits the spinal canal directly under the lower contour of the arch of the next underlying vertebra.

The superior articular process of the underlying vertebra increases in size caudally, while the inferior arch and spinous process of the overlying vertebra decrease in size..

spinal canal.

The anterior wall of the spinal canal (SC) is formed by the posterior surfaces of the vertebral bodies and intervertebral discs, which are covered by a common posterior longitudinal ligament. The ligament at the level of the intervertebral disc is wider than at the level of the middle of the vertebral body, where it is separated from the bone tissue by the venous plexus. This ligament is not visible on CT scans..

The lateral walls of the SC are formed by the arches of the vertebrae, between which the intervertebral foramens pass.. The back wall is formed by the arches of the vertebrae and the spaces between them, covered with yellow ligaments.. Laterally, this ligament is attached to the upper inner part of the posterior articular capsule and limits the upper articular pocket..

The SC consists of a central zone and lateral (radicular) canals. The central zone is formed alternately by fixed and movable segments. At the level of mobile segments, lateral (lateral) channels open.

Each channel is divided into three parts: interdisco-articular space; side pocket, the narrow part of which at the level of the upper edge of the temple should not be less than 5 mm; directly the intervertebral foramen, in the upper part of which the nerve root is located. In the lower part of the channel are adipose tissue and veins.

Of great clinical importance is the assessment of the size of the canal, since in the primary narrow spinal canal, even minimal manifestations of the degenerative-dystrophic process lead to serious consequences..

However, to date, there has not been a consensus on the Diagnostic criteria and the possibilities of certain methods of research and assessment of the size of the spinal canal.. So, for example, C. Urlich and co-authors in a CT study of the lumbar SMS attach great importance to the sagittal diameter of the SC. The authors consider the SC to be absolutely narrow with a sagittal diameter of less than 11.5 mm..

According to N. Verbist, when evaluating the results of CT, the diagnostic criterion for absolute stenosis of the lumbar spinal canal is the sagittal diameter of the latter, equal to 10 mm or less, relative stenosis - 10-12 mm.

Mrowka and J. Pieniaser sagittal diameter of the spinal canal less than 15 mm is regarded as pathological. J is of the same opinion.. Laredo, M. Bard, considering that, according to CT data, the anteroposterior diameter at the level of fixed segments should normally exceed 15 mm. With sizes less than 12 mm, the authors consider the lumbar SC as a primary (absolutely) narrow.

According to F. Ermolenko and co-authors (cited. by A. Sitel), normally the width of the SC in the sagittal plane at the LIII level is on average 39.1 mm, LIV - 39.4 mm. Permissible deviations from the average values, according to the authors, are for level LIII - 2.2 mm, LIV - 2.5 mm.

We cannot agree with A.. Sitel that the sagittal diameter of the spinal canal corresponds to the width of the intervertebral foramen. There is no consensus in the assessment of the frontal diameter of the SC. Yes, M. Gado et al. use the following data as criteria for frontal stenosis: for the LIV-LV level, a decrease in the frontal diameter of the capal to 16 mm or less, for the LV-SI level, less than 20 mm.

At the same time F. Ermolenko et al. (cit.. by A. Sitel) consider that normally the frontal diameter of the spinal canal for the Lin level is on average 27.3 mm, LIV - 28.2 mm, LV - 31.3 mm. Permissible deviations from the average values, according to the authors, are for the level LII - 1.7 mm, LIII - 1.9 mm, LV - 2.7 mm.

Computed tomography semiotics of degenerative-dystrophic pathology of the lumbar vertebral motor segments.

It is known that degenerative-dystrophic changes, depending on the stage of the process, are subject to all structures that form PDS-bodies, vertebrae, intervertebral discs, facet joints, ligaments. In this regard, the clinical manifestations of the process at each stage are due to the predominance or combination of degenerative-dystrophic changes in certain structures of the PDS..

Currently, in the domestic and foreign literature, numerous computed tomographic signs of degenerative-dystrophic changes in the lumbar SMS are described..

However, to date, there is no systematization of CT signs of degenerative-dystrophic processes in the lumbar SMS and a common terminology in their description in the literature, which greatly complicates the clinical interpretation of data obtained using computed tomography..

Description of CT symptoms, let's start with consideration of signs of intervertebral disc degeneration, since it is well known that pathological changes in MD are the most common cause of neurological symptoms in lumbar osteochondrosis.

Computed tomographic semiotics of degenerative-dystrophic changes in intervertebral discs.

The earliest sign of a degenerative-dystrophic lesion of MD is a diffuse protrusion of the contour of the latter beyond the contour of the vertebral body, due to radial tears of the annulus fibrosus. There are two terms in the literature that are used by the authors to refer to diffuse protrusion of the disc - protrusion and prolapse.

Of clinical importance are deformations of the posterior contour of the intervertebral disc, leading to narrowing of the spinal canal and radicular foramina.. Various types of diffuse protrusions of MD have been described in the literature.. Yes, M. Gado et al distinguish protrusion of the posterior edge of the MD along the midline - central and protrusion in the immediate vicinity of the midline - posterolateral protrusion.

Bokarev et al.. diffuse protrusion is distinguished - protrusion of the intervertebral disc beyond the edges of the vertebral bodies along its entire circumference with a symmetrical introduction into the region of the spinal canal and channels of the spinal nerves and local asymmetric protrusion of the MD.

With narrowing of the lateral pocket or canal of the spinal nerve on the corresponding side.

Yakhno and co-authors suggest distinguishing the following types of diffuse protrusions (prolapses) of MD:.

- in direction - medial, unilateral mediolateral, bilateral mediolateral and circular;

- according to the severity - non-rough prolapses (2-3 mm), prolapses of medium size (4-6 mm) and large prolapses (up to 9 mm).

The second important CT sign of a degenerative-dystrophic lesion of the intervertebral disc is the so-called " In patients with degenerative-dystrophic lesions, the gas consists of a mixture of predominantly nitrogen with oxygen, carbon dioxide and traces of other gases that are released from the interstitial fluid when the hydrostatic pressure in the affected MD changes and are poorly absorbed in its avascular tissue..

The gas can also be localized in different parts of the MD, occupying both the central and peripheral zones of the latter.. However, the authors interpret the diagnostic value of the “vacuum phenomenon” differently.. Yes, L. Ford and colleagues believe that the amount of gas in the affected intervertebral disc depends more on the magnitude of hydrostatic pressure than on the stage of the pathological process and cannot serve as a predictor of the severity of the disease..

A is of the same opinion. Kishkovsky and co-authors. The authors point out that in the 10 patients they examined with the “vacuum phenomenon”, the volume of gas did not depend on the duration of the disease and the severity of neurological symptoms.. At the same time, the authors believe that the presence of gas in the disc tissue can serve as a fairly reliable CT symptom of a degenerative spinal lesion..

Bokarev et al attribute the " However, according to Dmitriev A.. and co-authors " At the same time L. Ford et al., A. Gulati, G. Weinstein, M. Gado et al point out that "

In addition, L. Ford and co-authors and M. Gado and co-authors believe that the accumulation of gas along the posterior contour of the disc indicates a pronounced thinning of the fibrous ring in this area.. It is also important to note that when the annulus ruptures, gas from the MD can enter the spinal canal or retroperitoneal space, which should be taken into account when interpreting the CT picture..

One of the most important manifestations of the degenerative-dystrophic pathology of the lumbar PDS in clinical terms is hernia of the MD.. Most authors believe that, unlike protrusion (prolapse), a herniated disc is the result of displacement and extrusion of the nucleus pulposus from its bed..

Local protrusion along the edge is a direct CT symptom of disc herniation. In addition, a large number of indirect CT symptoms of MD hernia are described in the literature, the diagnostic significance of each of which is interpreted differently by different authors..

So, V M. Haughton et al., M. Gado et al. indirect CT symptoms of MD hernia include the following:.

1) Displacement of epidural tissue and the appearance of tissue density structures in the extradural space of the spinal canal. With the formation of a hernia of the intervertebral disc, which, as a rule, has a soft-tissue density, a displacement of a lower-density epidural fiber occurs, causing asymmetry of the latter.. Soft tissue density in the epidural space represents the size and location of the MD herniation.

2) Deformation of the dural sac. With the formation of a hernia of the MD, deformation of the contour of the dural sac may develop.. The dural sac can take the shape of a crescent due to compression by a massive herniated protrusion of the intervertebral disc of median localization.. However, in the lower lumbar region, where the dural sac is small, the volume of the MD herniation may be sufficient to compress the spinal roots without causing deformation of the dural sac..

3) Compression and displacement of the spinal roots. Pointing out that compression and displacement of the nerve roots can develop in the lumen of the spinal canal in the lateral location of the MD hernia, the authors note that in most cases in such a situation, the CT image fails to separate the image of the root from the herniated protrusion of the intervertebral disc.

Bokarev V. and co-authors, as indirect CT symptoms of MD hernia, distinguish: obliteration of the epidural space with structures of increased uneven densitometric density, a decrease in the density of the dorsal part of the disc, a “vacuum phenomenon”, asymmetry or a change in the position of the outgoing nerve roots. According to the authors, the symptom of deformation of the anterior contour of the dural sac is of decisive clinical importance..

At the same time Dmitriev A. and co-authors do not subdivide CT symptoms of MD hernia into direct and indirect, describing the following, in their opinion, the most characteristic signs of a hernia:.

- deformation of the posterior border of the disc in the form of its local prolapse beyond the posterior edge of the vertebral body;

- deformity of the epidural tissue;

- the presence of a soft tissue component in the epidural space;

- mixing and deformation of the dural sac and spinal roots.

The manifestation of a soft tissue component above and below the level of the intervertebral disc indicates, according to the authors, a significant size of the hernial protrusion and is a direct CT sign of sequestration.. The authors agree with the opinion that the area of \u200b\u200bincreased density in the zone of MD hernia and calcification of the posterior contour of the hernia in the zone of the posterior longitudinal ligament indicates a significant period of the pathological process..

There was no consensus on the classification of MD hernias depending on the direction of the hernial protrusion..

Yes, V. Bokarev and co-authors, depending on the localization, distinguish between posterior, posterolateral and lateral herniated discs..

Akimov and V. Kovalenko subdivide MD hernias into median, paramedian and posterolateral.

Dmitriev et al distinguish between central and paramedian MD hernias.

Sitel classifies MD hernias as follows: paramedian, median-foramenal, and foramenal.. It should be noted that on the lumbar PDS computed tomograms cited by the author as illustrations, the paramedian hernia corresponds to its name in terms of localization, but at the same time, the hernia, called foramenal, is a massive symmetrical posterior protrusion of the MD, and the so-called median-foramenal hernia is a local lateral protrusion of the MD.

One of the severe manifestations of the degenerative-dystrophic process in the lumbar PDS is the rupture of the fibrous ring of MD with protrusion of the nucleus pulposus. Lateral disc ruptures are atypical.

The prolapsed fragment can be displaced through tears in the posterior longitudinal ligament and be located freely in the epidural space.. This condition is called extrusion and appears on CT as an additional soft-bodied component in the epidural space that has no connection with the MD tissue..

Fragment migration occurs more often in the caudal direction, less often in the cranial direction.. Possible displacement of the fragments should be taken into account when compiling CT findings and the clinical level of neurological deficit.

An additional CT symptom of extrusion is the presence of gas in the epidural space.. Luft and co-authors, using contrast CT discography during extrusion, observed the release of a contrast agent from the disc into the lumen of the spinal canal and intervertebral foramen.

Computed tomographic semiotics of degenerative-dystrophic changes in facet joints.

The second most common cause of neurological symptoms in degenerative-dystrophic lesions of the lumbar spine is lumbar spondylarthrosis.. The medical literature describes the following CT symptoms of degenerative-dystrophic lesions of the facet joints: narrowing of the joint space, hypertrophy of the joint capsules, hypertrophy of the yellow ligaments, accumulation of air in the joint cavity, the presence of bone growths along the edges of the articular surfaces.

The development of osteophytes of the articular surfaces in the direction can be medial, lateral and vertical. Medial osteophytes can cause nerve root irritation; vertical, causing elongation of the superior articular process, leading to an effect on the nerve ganglion; lateral osteophytes have no clinical significance.

It should be noted that degenerative changes in the DS cause narrowing of the lateral canals and intervertebral foramens.. It is possible to judge the state of these structures, the degree of their narrowing only by CT. Standard radiography does not provide such information..

Computed tomographic semiotics of degenerative-dystrophic changes in the vertebral bodies.

The two most common manifestations of degenerative-dystrophic changes in the vertebral bodies are known - Schmorl's hernia and deforming spondylosis..

On CT, degenerative changes in the vertebral bodies are well visualized both on the lateral tomogram, where their images are identical to those obtained using standard radiography of the spine in the lateral projection, and on axial sections passing near, as well as through the endplates of the vertebral bodies.

On axial sections, Schmorl's hernias look like more or less rounded formations of soft tissue density in denser bone tissue, surrounded by an osteosclerotic border around the perimeter..

Marginal bone growths of the vertebral bodies on axial sections are represented by formations of various shapes and sizes, located along the perimeter of the vertebral body contour and having a densitometric density identical to that of the body..

If osteophytes are not located parallel to the plane of the endplates and are of considerable size, then they can be visualized at the MD level as formations of high densitometric density along the MD perimeter..

Of clinical importance are osteophytes growing in the lumen of the SC and radicular foramina.. Diagnosis of osteophytes of such localization and assessment of their impact on the contents of the SC and radicular foramens is possible only with a computer study..

Computed tomographic semiotics of degenerative stenosis of the lumbar spinal canal.

Unlike primary (absolute, idiopathic) stenosis of the spinal canal, which is a congenital anomaly of the skeleton, degenerative stenosis of the SC is formed as a result of degenerative-dystrophic changes that develop in various structures of the SMS..

Central stenosis of the SC due to hypertrophy of the lower articular processes and arches. This condition can be complicated by posterior MD prolapses and osteophytes of the vertebral bodies, which leads to a decrease in the sagittal diameter of the spinal canal.

Stenosis of the lateral canals (lateral stenosis) due to hypertrophy of the superior articular processes that form the posterior wall of the bony canal of the spinal root. This hypertrophy is accompanied by narrowing of the radicular foramen.

With lateral stenosis, the spinal canal on CT takes the form of a trefoil, however, as the authors note, this form of SC is the norm at the level of LIV and LV. The authors consider stenosis of the SC in spondylolisthesis to be a type of lateral stenosis, which may accompany degenerative-dystrophic pathology of the lumbar SMS.

Anterior displacement of the posterior elements of the overlying vertebra may be accompanied by compression of the roots in the lateral canals. In such a situation, CT scans performed at the level of the movable segment in the listes zone simultaneously show the structures of two adjacent vertebrae (Fig.. 1).

Foramental stenosis developing as a result of expressions of hypertrophy and elongation of the superior articular process or its cranial displacement due to a pronounced decrease in the height of the MD. Levit, J. Sachse and V. Janda note that the diagnosis of foramental stenosis is difficult due to the lack of objective data on the size of the radicular foramen and is based mainly on subjective feelings and experience.. According to these authors, the image reformation passing through the radicular holes makes it possible to visualize the compressing agent..

It should be noted that, apart from the works of the mentioned authors, no other works on CT semiotics of degenerative stenosis of the lumbar spinal canal have been found in the available literature.. In the domestic literature there is a single work by Yu. Shanko, dedicated to the features of the clinic and diagnosis of stenosis of the lumbar SC, which, however, lacks diagnostic criteria for stenosis of the SC.

As for the works of foreign authors mentioned above, their descriptive nature and the absence of clear diagnostic criteria for degenerative stenosis of the spinal canal are quite obvious..

Protsenko developed a new method of computed tomography diagnostics of degenerative stenosis of the lumbar spinal canal, which consists in the following. The patient undergoes axial computed tomography at the level of the movable segment.

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