The spinal canal dimensions are normal cervical. Expected results of surgical treatment for absolute narrowing of the cervical spinal cord. Functions of gray matter

The spinal cord is a cord of nerve tissue located inside the bony canal of the spine. In an adult, its length is 41−45 cm, and its diameter is 1−1.5 cm. The spinal cord and brain are the central links of the nervous system.

At the top, the spinal cord merges with the medulla oblongata. Its lower extremity at the 2nd lumbar vertebra becomes thinner, turning into a medullary cone. Next, the rudimentary spinal cord in the form of a terminal filament penetrates the sacral canal, attaching to the periosteum of the coccyx. At the points where the spinal nerves exit to the upper and lower extremities, cervical and lumbar thickenings of the brain are formed.
The anterior concave surface of the medullary cord along its length forms the anterior median fissure. Posteriorly, the surface of the brain is divided by a narrow median sulcus. These lines divide it into symmetrical halves. The motor anterior and sensory posterior nerve roots emerge along the lateral surfaces of the brain. The posterior nerve roots consist of processes of sensory neuron cells. They enter the brain along the posterolateral sulcus. The anterior roots are formed by the axons of motor cells - motor neurons. The processes emerge from the brain substance in the anterolateral sulcus. Before leaving the spinal canal, the sensory and motor nerve roots unite, forming symmetrical pairs of mixed spinal nerves. These nerves, leaving the bone canal between 2 adjacent vertebrae, are directed to the periphery. The length of the bony canal of the spine exceeds the length of the medullary cord. The reason for this is the high rate of bone growth compared to nerve tissue. Therefore, in the lower parts of the spine, the nerve roots are located vertically.

The anterior and posterior spinal arteries, as well as the spinal branches of the segmental branches of the descending aorta - the lumbar and intercostal arteries, supply blood to the structures of the spinal cord and spine.
In the section, you can discern the internal structure of the brain tissue. In the center, shaped like a butterfly or a capital H, there is gray matter surrounded by white matter. Along the entire length of the nerve cord there is a central canal containing cerebrospinal fluid. The lateral projections of the gray matter form gray pillars. In section, the pillars are visible as the posterior horns, formed by the bodies of sensory neurons, and the anterior horns, consisting of the bodies of motor cells. The halves of the “butterfly” are connected by a bridge made of a central intermediate substance. The area of ​​the brain with a pair of roots is called the spinal segment. Humans have 31 spinal segments. The segments are grouped by location: 8 are in the cervical region, 12 in the thoracic region, 5 in the lumbar region, 5 in the sacral region, 1 in the coccygeal region.

The white matter of the brain is composed of processes of nerve cells - sensory dendrites and motor axons. Surrounding the gray matter, it also consists of 2 halves, connected by a thin white commissure - the commissure. The cell bodies of neurons themselves can be located in any part of the nervous system.

Bundles of nerve cell processes carrying signals in one direction ( only to centers or only from centers), are called conductive pathways. The white matter in the spinal cord is combined into 3 pairs of cords: anterior, posterior, lateral. The anterior funiculi are limited by the anterior columns. The lateral funiculi are delimited by the posterior and anterior columns. The lateral and anterior cords carry conductors of 2 types. The ascending pathways carry signals to the CNS - the central parts of the nervous system. And the descending pathways go from the nuclei of the central nervous system to the motor neurons of the anterior horns. The posterior funiculi run between the posterior columns. They represent ascending pathways that carry signals to the brain - the cerebral cortex. This information forms the joint-muscular feeling - an assessment of the location of the body in space.

Embryonic development

The nervous system is formed in the embryo at the age of 2.5 weeks. On the dorsal side of the body, a longitudinal thickening of the ectoderm is formed - the neural plate. Then the plate bends along the midline and becomes a groove limited by the neural folds. The groove closes into the neural tube, separating itself from the skin ectoderm. The anterior end of the neural tube thickens and becomes the brain. The spinal cord develops from the rest of the tube.

The length of the spinal cord of newborn children in relation to the size of the spinal canal is greater than that of an adult. In children, the spinal cord reaches the 3rd lumbar vertebra. Gradually, the growth of nervous tissue lags behind the growth of bone tissue of the spine. The lower end of the brain moves upward. At 5–6 years of age, the ratio of the length of the spinal cord to the size of the spinal canal in a child becomes the same as that of an adult.

In addition to conducting nerve impulses, the purpose of the spinal cord is to close unconditioned motor reflexes at the level of the spinal segments.

Diagnostics

The spinal reflex is the contraction of a muscle in response to stretching of its tendon. The severity of the reflex is checked by tapping the muscle tendon with a neurological hammer. Based on the state of individual reflexes, the location of the lesion in the spinal cord is determined. When a segment of the spinal cord is damaged, deep and superficial sensitivity occurs in the corresponding areas of the body - the dermatomes. Spinal autonomic reflexes also change - visceral, vascular, urinary.

The movements of the limbs, their muscle tone, and the severity of deep reflexes characterize the work of the descending conductors in the anterior and lateral cords of the brain. Determining the area of ​​disturbance of tactile, temperature, pain and joint-muscular sensitivity helps to find the level of damage to the posterior and lateral cords.

To clarify the localization of the lesion in the brain, determine the nature of the disease ( inflammation, hemorrhage, tumor) additional research is needed. A spinal tap will help assess cerebrospinal fluid pressure and the condition of the meninges. The resulting liquor is examined in the laboratory.

The state of sensory and motor neurons is assessed by electroneuromyography. The method determines the speed of impulses passing through motor and sensory fibers and records electrical potentials of the brain.

X-ray studies reveal lesions of the spinal column. In addition to general radiography of the spine, X-ray tomography is performed to detect cancer metastases. This allows us to detail the structure of the vertebrae, the condition of the spinal canal, and identify desalination of the meninges, their tumors and cysts. Previous X-ray methods ( pneumomyelography, contrast myelography, spinal angiography, venospondylography) today have given way to painless, safe and highly accurate methods - magnetic resonance and computed tomography. The anatomical structures of the spinal cord and spine are clearly visible on MRI.

Diseases and injuries

A spinal injury can result in a concussion, contusion, or rupture of the spinal cord. The most serious consequences are a rupture - a violation of the integrity of brain tissue. Symptoms of damage to the brain substance are paralysis of the muscles of the trunk and limbs below the level of injury. After concussions and bruises of the spinal cord, it is possible to treat and restore the function of temporarily paralyzed muscles of the trunk and limbs.

Inflammation of the soft membrane of the spinal cord is called meningitis. Treatment of infectious inflammation is carried out with antibiotics, taking into account the sensitivity of the identified pathogen.

When a herniated intervertebral cartilaginous disc prolapses, compression of the nerve root develops. Symptoms of root compression in everyday life are called radiculitis. These are severe pain and sensory disturbances along the corresponding nerve. The root is released from compression during a neurosurgical operation to remove an intervertebral hernia. Now such operations are performed using a gentle endoscopic method.

About transplantation

The current level of medicine does not allow spinal cord transplantation. With its traumatic ruptures, patients remain confined to a wheelchair. Scientists are developing methods to restore spinal cord function after severe injury using stem cells. Currently the work is in the experimental stage.

Most severe spinal cord and spinal injuries are the result of motor vehicle accidents or suicide attempts. As a rule, such events occur against the background of alcohol abuse. By refusing excessive libations and following traffic rules, you can protect yourself from serious injuries.

Based on the book:
Degenerative-dystrophic lesions of the spine (radiation diagnostics, complications after disectomy)

Rameshvili T.E. , Trufanov G.E., Gaidar B.V., Parfenov V.E.

Spinal column

The spinal column is normally a flexible formation, consisting in the average version of 33-34 vertebrae, connected into a single chain by intervertebral discs, facet joints and powerful ligaments.

The number of vertebrae in adults is not always the same: there are anomalies in the development of the spine associated with both an increase and a decrease in the number of vertebrae. Thus, the 25th vertebra of the embryo in an adult is assimilated by the sacrum, but in some cases it does not fuse with the sacrum, forming the 6th lumbar vertebra and 4 sacral vertebrae (lumbarization - the assimilation of the sacral vertebra to the lumbar).

There are also opposite relationships: the sacrum assimilates not only the 25th vertebra but also the 24th, forming 4 lumbar and 6 sacral vertebrae (sacralization). Assimilation can be complete, bone, incomplete, bilateral and unilateral.

The following vertebrae are distinguished in the spinal column: cervical - 7, thoracic - 12, lumbar - 5, sacral - 5 and coccygeal - 4-5. Moreover, 9-10 of them (sacral - 5, coccygeal - 4-5) are connected motionlessly.

Normally, there is no curvature of the spinal column in the frontal plane. In the sagittal plane, the spinal column has 4 alternating smooth physiological curves in the form of arcs convexly directed anteriorly (cervical and lumbar lordosis) and arcs convexly directed posteriorly (thoracic and sacrococcygeal kyphosis).

The normal anatomical relationships in the spinal column are evidenced by the severity of physiological curves. The physiological curves of the spine are always smooth and are not normally angular, and the spinous processes are at the same distance from each other.

It should be emphasized that the degree of curvature of the spinal column in different parts is not the same and depends on age. Thus, at the time of birth, curves of the spinal column exist, but their severity increases as the child grows.

Vertebra

A vertebra (except for the two upper cervical ones) consists of a body, an arch and processes extending from it. The vertebral bodies are connected by intervertebral discs, and the arches by intervertebral joints. The arches of adjacent vertebrae, joints, transverse and spinous processes are connected by a powerful ligamentous apparatus.

The anatomical complex, consisting of an intervertebral disc, two corresponding intervertebral joints and ligaments located at this level, represents a unique segment of spinal movements - the so-called. spinal motion segment. The mobility of the spine in a single segment is small, but the movements of many segments provide the possibility of significant mobility of the spine as a whole.

The size of the vertebral bodies increases in the caudal direction (from top to bottom), reaching a maximum in the lumbar region.

Normally, the vertebral bodies have the same height in the anterior and posterior sections.

An exception is the fifth lumbar vertebra, the body of which is wedge-shaped: in the ventral section it is higher than in the dorsal section (higher in the front than in the back). In adults, the body has a rectangular shape with rounded corners. In the transitional thoracolumbar spine, a trapezoidal body of one or two vertebrae may be detected with a uniform bevel of the upper and lower surfaces anteriorly. The lumbar vertebra may have a trapezoidal shape with a posterior slope of the upper and lower surfaces. A similar shape to the fifth vertebra is sometimes mistaken for a compression fracture.

The vertebral body consists of spongy substance, the bone beams of which form a complex interweaving, the vast majority of them have a vertical direction and correspond to the main lines of load. The anterior, posterior and lateral surfaces of the body are covered with a thin layer of dense substance perforated by vascular canals.

An arch extends from the superolateral parts of the vertebral body, in which two parts are distinguished: the anterior, paired - pedicle and the posterior - plate ( Iamina), located between the articular and spinous processes. The following processes extend from the vertebral arch: paired - upper and lower articular (arcicular) processes, transverse and single - spinous.

The described structure of the vertebra is schematic, since individual vertebrae not only in different sections, but also within the same section of the spinal column may have distinctive anatomical features.

A feature of the structure of the cervical spine is the presence of holes in the transverse processes of the CII-CVI vertebrae. These openings form a canal through which the vertebral artery passes with the sympathetic plexus of the same name. The medial wall of the canal is the middle part of the semilunar processes. This should be taken into account when the deformation of the semilunar processes increases and arthrosis of the unco-vertebral joints occurs, which can lead to compression of the vertebral artery and irritation of the sympathetic plexuses.

Intervertebral joints

Intervertebral joints are formed by the lower articular processes of the overlying vertebra and the upper articular processes of the underlying one.

The facet joints in all parts of the spinal column have a similar structure. However, the shape and location of their articular surfaces are not the same. Thus, in the cervical and thoracic vertebrae they are located in an oblique projection, close to the frontal, and in the lumbar vertebrae - to the sagittal. Moreover, if in the cervical and thoracic vertebrae the articular surfaces are flat, then in the lumbar vertebrae they are curved and look like segments of a cylinder.

Despite the fact that the articular processes and their articular surfaces in various parts of the spinal column have unique features, at all levels the articulating articular surfaces are equal to one another, lined with hyaline cartilage and reinforced by a tightly stretched capsule, attached directly to the edge of the articular surfaces. Functionally, all arcuate joints are classified as low-moving.

In addition to the facet joints, the true joints of the spine include:

• paired atlanto-occipital joint connecting the occipital bone with the first cervical spine;
• unpaired median atlanto-axial joint connecting vertebrae CI and CII;
• paired sacroiliac joint connecting the sacrum to the iliac bones.

Intervertebral disc

The bodies of adjacent vertebrae from the second cervical to the first sacral are connected by intervertebral discs. The intervertebral disc is cartilaginous tissue and consists of a pulpous nucleus ( nucleus pulposus), annulus fibrosus ( annulus fibrosis) and from two hyaline plates.

Nucleus pulposus - a spherical formation with an uneven surface, consists of a gelatinous mass with a high water content - up to 85-90% in the core, its diameter ranges from 1-2.5 cm.

In the intervertebral disc in the cervical region, the nucleus pulposus is displaced somewhat anterior to the center, and in the thoracic and lumbar regions it is located on the border of the middle and posterior third of the intervertebral disc.

The nucleus pulposus is characterized by great elasticity and high turgor, which determines the height of the disc. The core is compressed in a disk under pressure of several atmospheres. The main function of the nucleus pulposus is a spring: acting like a buffer, it weakens and evenly distributes the influence of various shocks and shocks over the surfaces of the vertebral bodies.

Thanks to its turgor, the nucleus pulposus exerts constant pressure on the hyaline plates, pushing the vertebral bodies apart. The ligamentous apparatus of the spine and the fibrous ring of the discs counteract the nucleus pulposus, bringing adjacent vertebrae closer together. The height of each disc and the entire spinal column as a whole is not a constant value. It is associated with the dynamic balance of oppositely directed influences of the nucleus pulposus and the ligamentous apparatus and depends on the level of this balance, which corresponds primarily to the state of the nucleus pulposus.

The tissue of the nucleus pulposus is capable of releasing and binding water depending on the load, and therefore at different times of the day the height of a normal intervertebral disc is different.

Thus, in the morning, the height of the disc increases with the restoration of the maximum turgor of the nucleus pulposus and, to a certain extent, overcomes the elasticity of the traction of the ligamentous apparatus after an overnight rest. In the evening, especially after physical activity, the turgor of the nucleus pulposus decreases and adjacent vertebrae come closer together. Thus, a person’s height changes during the day depending on the height of the intervertebral disc.

In an adult, intervertebral discs make up approximately a quarter or even a third of the height of the spinal column. The noted physiological fluctuations in growth during the day can be from 2 to 4 cm. Due to the gradual decrease in turgor of the nucleus pulposus in old age, growth decreases.

The peculiar dynamic counteraction of the influences on the spinal column of the nucleus pulposus and the ligamentous apparatus is the key to understanding a number of degenerative-dystrophic lesions developing in the spine.

The nucleus pulposus is the center around which mutual movement of adjacent vertebrae occurs. When the spine flexes, the core moves posteriorly. When extending anteriorly and when bending sideways - towards the convexity.

Fibrous ring , consisting of connective tissue fibers located around the nucleus pulposus, forms the anterior, posterior and lateral edges of the intervertebral disc. It is attached to the bony marginal edging through Sharpei fibers. The fibers of the fibrous ring are also attached to the posterior longitudinal ligament of the spine. The peripheral fibers of the annulus fibrosus make up the strong outer part of the disc, and the fibers located closer to the center of the disc are more loosely located, passing into the capsule of the nucleus pulposus. The anterior section of the fibrous ring is denser and more massive than the posterior one. The anterior part of the fibrous ring is 1.5-2 times larger than the posterior one. The main function of the fibrous ring is to fix adjacent vertebrae, hold the nucleus pulposus inside the disc, and ensure movement in different planes.

The cranial and caudal (upper and lower, respectively, in a standing position) surface of the intervertebral disc is formed by hyaline cartilaginous plates inserted into the limbus (thickening) of the vertebral body. Each of the hyaline plates is equal in size and tightly adjacent to the corresponding end plate of the vertebral body; it connects the nucleus pulposus of the disc with the bony end plate of the vertebral body. Degenerative changes in the intervertebral disc spread to the vertebral body through the endplate.

Ligamentous apparatus of the spinal column

The spinal column is equipped with a complex ligamentous apparatus, which includes: anterior longitudinal ligament, posterior longitudinal ligament, yellow ligaments, intertransverse ligaments, interspinous ligaments, supraspinous ligament, nuchal ligament and others.

Anterior longitudinal ligament covers the anterior and lateral surfaces of the vertebral bodies. It starts from the pharyngeal tubercle of the occipital bone and reaches the 1st sacral vertebra. The anterior longitudinal ligament consists of short and long fibers and bundles, which firmly grow together with the vertebral bodies and are loosely connected to the intervertebral discs; above the latter, the ligament is thrown from one vertebral body to another. The anterior longitudinal ligament also serves as the periosteum of the vertebral bodies.

Posterior longitudinal ligament starts from the upper edge of the foramen magnum, lines the posterior surface of the vertebral bodies and reaches the lower part of the sacral canal. It is thicker, but narrower than the anterior longitudinal ligament and richer in elastic fibers. The posterior longitudinal ligament, unlike the anterior one, is firmly fused with the intervertebral discs and loosely fused with the vertebral bodies. Its diameter is not the same: at the level of the discs it is wide and completely covers the posterior surface of the disc, and at the level of the vertebral bodies it looks like a narrow ribbon. On the sides of the midline, the posterior longitudinal ligament passes into a thin membrane that separates the venous plexus of the vertebral bodies from the dura mater and protects the spinal cord from compression.

Ligamentum flavumconsist of elastic fibers and connect the vertebral arches; they are especially clearly visualized on MRI in the lumbar spine, about 3 mm thick. The intertransverse, interspinous, and supraspinous ligaments connect the corresponding processes.

The height of the intervertebral discs gradually increases from the second cervical vertebra to the seventh, then a decrease in height is observed to ThIV and reaches a maximum at the level of the LIV-LV disc. The smallest heights are found in the uppermost cervical and upper thoracic intervertebral discs. The height of all intervertebral discs located caudal to the ThIV vertebral body increases uniformly. The presacral disc is very variable both in height and shape; deviations in one direction or another in adults are up to 2 mm.

The height of the anterior and posterior sections of the disc in different parts of the spine is not the same and depends on the physiological bends. Thus, in the cervical and lumbar regions, the anterior part of the intervertebral discs is higher than the posterior one, and in the thoracic region the opposite relationships are observed: in the middle position, the disc has the shape of a wedge, with its apex facing backwards. With flexion, the height of the anterior part of the disc decreases and the wedge-shaped shape disappears, and with extension, the wedge-shaped shape is more pronounced. There is normally no displacement of the vertebral bodies during functional tests in adults.

Spinal canal

The spinal canal is a container for the spinal cord, its roots and co-vessels; the spinal canal communicates cranially with the cranial cavity, and caudally with the sacral canal. For the exit of the spinal nerves from the spinal canal there are 23 pairs of intervertebral foramina. Some authors divide the spinal canal into a central part (dural canal) and two lateral parts (right and left lateral canals - intervertebral foramina).

In the side walls of the canal there are 23 pairs of intervertebral foramina, through which the roots of the spinal nerves and veins exit the spinal canal and the radicular-spinal arteries enter. The anterior wall of the lateral canal in the thoracic and lumbar regions is formed by the posterolateral surface of the bodies and intervertebral discs, and in the cervical region this wall also includes the uncovertebral joint; posterior wall - the anterior surface of the superior articular process and the facet joint, the yellow ligaments. The upper and lower walls are represented by cuttings of the legs of the arches. The upper and lower walls are formed by the inferior notch of the pedicle of the overlying vertebra and the superior notch of the pedicle of the underlying vertebra. The diameter of the lateral canal of the intervertebral foramina increases in the caudal direction. In the sacrum, the role of intervertebral foramina is played by four pairs of sacral foramina, which open on the pelvic surface of the sacrum.

The lateral (radicular) canal is externally limited by the pedicle of the overlying vertebrae, in front by the vertebral body and intervertebral disc, and behind by the ventral sections of the intervertebral joint. The radicular canal is a semi-cylindrical groove about 2.5 cm long, running from the central canal from top to bottom and anteriorly. The normal anteroposterior size of the canal is at least 5 mm. There is a division of the root canal into zones: the “entry” of the root into the lateral canal, the “middle part” and the “exit zone” of the root from the intervertebral foramen.

The “3rd entrance” to the intervertebral foramen is the lateral recess. The causes of root compression here are hypertrophy of the superior articular process of the underlying vertebra, congenital features of the development of the joint (shape, size), osteophytes. The serial number of the vertebra to which the superior articular process belongs in this type of compression corresponds to the number of the pinched spinal nerve root.

The “middle zone” is limited in front by the posterior surface of the vertebral body, in the back by the interarticular part of the vertebral arch, the medial sections of this zone are open towards the central canal. The main causes of stenosis in this area are osteophytes in the place of attachment of the yellow ligament, as well as spondylolysis with hypertrophy of the articular capsule of the joint.

In the “exit zone” of the spinal nerve root, the underlying intervertebral disc is located in front, and the outer parts of the joint are behind. The causes of compression in this area are spondyloarthrosis and subluxations in the joints, osteophytes in the area of ​​the upper edge of the intervertebral disc.

Spinal cord

The spinal cord begins at the level of the foramen magnum of the occipital bone and ends, according to most authors, at the level of the middle of the body of the LII vertebra (rarely occurring variants are described at the level of LI and the middle of the body of the LIII vertebra). Below this level is the terminal cistern containing the roots of the cauda equina (LII-LV, SI-SV and CoI), which are covered by the same membranes as the spinal cord.

In newborns, the end of the spinal cord is located lower than in adults, at the level of the LIII vertebra. By 3 years of age, the conus spinal cord occupies its usual adult location.

The anterior and posterior roots of the spinal nerves depart from each segment of the spinal cord. The roots are directed to the corresponding intervertebral foramina. Here the dorsal root forms the spinal ganglion (local thickening - ganglia). The anterior and posterior roots join just after the ganglion to form the spinal nerve trunk. The upper pair of spinal nerves leaves the spinal canal at the level between the occipital bone and the CI vertebra, the lower pair - between the SI and SII vertebrae. There are a total of 31 pairs of spinal nerves.

Up to 3 months, the roots of the spinal cord are located opposite the corresponding positions. Then the spine begins to grow more rapidly compared to the spinal cord. In accordance with this, the roots become longer towards the conus of the spinal cord and are located obliquely downwards towards their intervertebral foramina.

Due to the lag in the growth of the spinal cord in length from the spine, this discrepancy should be taken into account when determining the projection of the segments. In the cervical region, the spinal cord segments are located one vertebra higher than the corresponding vertebra.

There are 8 spinal cord segments in the cervical spine. Between the occipital bone and the CI vertebra there is a segment C0-CI where the CI nerve passes. Spinal nerves corresponding to the underlying vertebra emerge from the intervertebral foramen (for example, CVI nerves emerge from the intervertebral foramen CV-CVI).

There is a discrepancy between the thoracic spine and the spinal cord. The upper thoracic segments of the spinal cord are located two vertebrae higher than their corresponding vertebrae, and the lower thoracic segments are three. The lumbar segments correspond to the ThX-ThXII vertebrae, and all sacral segments correspond to the ThXII-LI vertebrae.

The continuation of the spinal cord from the level of the LI vertebra is the cauda equina. The spinal roots arise from the dural sac and diverge inferiorly and laterally to the intervertebral foramina. As a rule, they pass near the posterior surface of the intervertebral discs, with the exception of the roots LII and LIII. The spinal root LII emerges from the dural sac above the intervertebral disc, and the spinal root LIII exits below the disc. The roots at the level of the intervertebral discs correspond to the underlying vertebra (for example, the level of the LIV-LV disc corresponds to the LV root). The intervertebral foramen includes roots corresponding to the overlying vertebra (for example, LIV-LV corresponds to the LIV root).

It should be noted that there are several places where the roots can be affected in posterior and posterolateral herniated intervertebral discs: the posterior part of the intervertebral discs and the intervertebral foramen.

The spinal cord is covered by three meninges: dura ( dura mater spinalis), arachnoid ( arachnoidea) and soft ( pia mater spinalis). The arachnoid and pia mater together are also called leptomeningeal membrane.

Dura mater consists of two layers. At the level of the foramen magnum, the two layers completely separate. The outer layer is tightly adjacent to the bone and is, in fact, periosteum. The inner layer forms the dural sac of the spinal cord. The space between the layers is called the epidural ( cavitas epidura-lis), epidural or extradural.

The epidural space contains loose connective tissue and venous plexuses. Both layers of the dura mater are joined together as the spinal nerve roots pass through the intervertebral foramina. The dural sac ends at the level of the SII-SIII vertebrae. Its caudal part continues as the filum terminale, which is attached to the periosteum of the coccyx.

The arachnoid mater consists of a cell membrane to which a network of trabeculae is attached. The arachnoid membrane is not fixed to the dura mater. The subarachnoid space is filled with circulating cerebrospinal fluid.

Pia mater lines all surfaces of the spinal cord and brain. The trabeculae of the arachnoid membrane are attached to the pia mater.

The upper border of the spinal cord is the line connecting the anterior and posterior segments of the CI vertebral arch. The spinal cord ends, as a rule, at the level LI-LII in the form of a cone, below which there is a cauda equina. The roots of the cauda equina emerge at an angle of 45° from the corresponding intervertebral foramen.

The dimensions of the spinal cord are not the same along its entire length; its thickness is greater in the area of ​​the cervical and lumbar thickening. The sizes vary depending on the part of the spine:

• at the level of the cervical spine - the anteroposterior size of the dural sac is 10-14 mm, the spinal cord - 7-11 mm, the transverse size of the spinal cord approaches 10-14 mm;
• at the level of the thoracic spine - the anteroposterior size of the spinal cord corresponds to 6 mm, the dural sac - 9 mm, with the exception of the level of the ThI-Thll vertebrae, where it is 10-11 mm;
• in the lumbar spine - the sagittal size of the dural sac varies from 12 to 15 mm.

Epidural fat more developed in the thoracic and lumbar parts of the spinal canal.

Introduction

The average diameter of the spinal canal in the cervical spine ranges from 14 to 25 mm J.G. Arnold (1955), the size of the spinal cord ranges from 8 to 13 mm, and the thickness of the soft tissues (shell and ligaments) ranges from 2 to 3 mm. Thus, the average reserve space in the ventrodorsal direction, in the cervical spine, is approximately 3 mm. Considering the above, we can conclude that a decrease in the diameter of the spinal canal by 3 mm leads to compression of the spinal cord; accordingly, this condition is regarded as spinal canal stenosis. With more than 30% narrowing of the diameter of the spinal canal, cervical myelopathy develops. At the same time, in some patients with significant narrowing of the spinal canal, myelopathy is not observed. The diagnosis of cervical spinal canal stenosis is made when the anteroposterior size of the latter decreases to 12 mm or less. A narrowing of the spinal canal to 12 mm is considered relative stenosis, while a decrease in this size to 10 mm is absolute stenosis. In turn, the average size of the spinal canal in patients with cervical myelopathy is 11.8 mm. Patients with a spinal canal diameter of 14 mm are at risk. When the size of the spinal canal decreases to 10 mm, myelopathy is inevitable. Myelopathy rarely develops in patients with a spinal canal diameter of 16 mm. Clinical picture of cervical myelopathy

Table 1

Cervical myelopathy
Myelopathy and radiculopathy
Hyperreflexia
Babinski reflex
Hofmann reflex
Conductive sensory disturbances
Radicular sensory disturbances
Disturbances of deep feeling
Instability in the Romberg position
Monoparesis of the arm
Paraparesis
Hemiparesis
Tetraparesis
Brown-Séquard syndrome
Muscle atrophy
Fascicular twitching
Radicular pain in the arms
Radicular pain in the legs
Cervicalgia
Muscle spasticity
Disorders of the pelvic organs

is very diverse and is represented in a late stage by syndromes reminiscent of many neurological diseases: multiple sclerosis, spinal cord tumors, spinocerebellar degenerations. In 50 percent of patients with severe clinical manifestations of spinal stenosis, there is usually a constant progression of symptoms. Conservative treatment, according to a number of authors, is little or not at all effective for this disease. The frequency of various symptoms with cervical spinal stenosis is given in Table. 1.

All this variety of symptoms develops into 5 main clinical syndromes for cervical spinal stenosis - transverse spinal cord syndrome, pyramidal syndrome with predominant damage to the main corticospinal tract, centromedullary syndrome with motor and sensory disturbances in the upper extremities, Brown-Séquard syndrome (damage to half the diameter spinal cord) and cervical dyscalgia.

The goal of surgical treatment for spinal stenosis is to eliminate compression of the spinal cord and the roots of their vessels. Positive results of surgical treatment, according to various authors, range from 57-96 percent, but some authors believe that surgery for spinal stenosis, at best, stops the progression of neurological deficit, but does not lead to complete recovery. The results of surgical treatment for absolute stenosis of the cervical spine are even more inconclusive.

Purpose of the study

Determination of the feasibility of surgical treatment of absolute stenosis of the cervical spinal canal.

Material and methods

In the Department of Neurosurgery of the Mikaelyan Institute of Surgery from 2001-2011. 33 patients (29 men, 4 women) aged from 34 to 71 years were operated on, with a diagnosis of cervical spinal canal stenosis and cervical myelopathy. The diagnosis was made on the basis of complaints, anamnesis, clinical picture, MRI examination of the cervical spine, ENMG. According to the neurological picture, they are divided into 3 groups (Table 2).

table 2

The anteroposterior size of the spinal canal ranged from 4 to 8 mm (Table 3), and the extent of compression ranged from one level to three (Table 4).

Table 3

Channel size s\m	3 mm	4 mm	5 mm	6 mm	7 mm	12 mm
Number of patients

Table 4

Decompression of the spinal cord was performed using an anterior or posterior approach, depending on the compressive agent. Anterior decompression - discectomy according to Cloward followed by spinal fusion with an autograft and fixation with a metal plate was performed if the compressive agent was the anterior wall of the spinal canal, namely a herniated intervertebral disc and ossified posterior longitudinal ligament; posterior decompression - laminectomy at stenotic levels was performed if there was hypertrophied vertebral arches and ossified ligamentum flavum - the posterior wall of the spinal canal.

Research results

The result was assessed as follows. Excellent - no neurological deficit or minimal sensory impairment. Good - an increase in muscle strength by 1-2 points, minimal sensory disturbances, while the muscle strength of the limbs after treatment should be at least 4 points. Satisfactory - increase in muscle strength by 1 point, sensory disorders, neuropathic pain in the extremities. Unsatisfactory - lack of effect from surgical treatment, dysfunction of the pelvic organs (acute urinary retention, constipation). Bad - worsening neurological deficit, respiratory failure, death. An excellent result was obtained in 1 patient, good in 12, satisfactory in 13, unsatisfactory in 6 and poor in 1 patient (Table 5).

Table 5

Size sp\k. mm	1 bad	2 bad	3 beats	4 chorus	5 ex.

Discussion of results and conclusions

In group 1 with a poor result, we had one death due to ascending edema of the spinal cord and trunk. This patient had spinal canal stenosis at the level of C3 up to 3 mm due to the discosteophyte complex; anterior decompression was performed - discectomy, followed by spinal fusion with an autograft and fixation with a metal plate. In group 2 with an unsatisfactory result, we have 6 patients with a spinal canal size of less than 5 mm, in 2 of them the spinal canal was stenotic due to a discosteophytic complex at two levels; they underwent discectomy followed by spinal fusion with an autograft at two levels.

Thus, the risk factor for surgical treatment of spinal canal stenosis is the upper cervical region and narrowing of the spinal canal to 3 mm. An unsatisfactory result can be expected with a narrowing of the spinal canal to 5 mm, as well as multi-level narrowing of the spinal canal due to the anterior wall - herniated intervertebral discs and ossified posterior longitudinal ligament.

Bibliography

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Photograph of an anatomical specimen) are the main element connecting the spinal column into a single whole, and make up 1/3 of its height. The main function of intervertebral discs is mechanical (support and shock-absorbing). They provide flexibility to the spinal column during various movements (bending, rotation). In the lumbar spine, the diameter of the discs is on average 4 cm, and the height is 7–10 mm. The intervertebral disc has a complex structure. In its central part there is a nucleus pulposus, which is surrounded by a cartilaginous (fibrous) ring. Above and below the nucleus pulposus are the end plates.

The nucleus pulposus contains well-hydrated collagen (randomly arranged) and elastic (radially arranged) fibers. At the border between the nucleus pulposus and the fibrous ring (which is clearly defined up to 10 years of life), cells resembling chondrocytes are located with a fairly low density.

Fibrous ring consists of 20–25 rings or plates, between which collagen fibers are located, which are directed parallel to the plates and at an angle of 60° to the vertical axis. Elastic fibers are located radially in relation to the rings, which restore the shape of the disc after the movement has taken place. The cells of the annulus fibrosus, located closer to the center, have an oval shape, while at its periphery they elongate and are located parallel to the collagen fibers, resembling fibroblasts. Unlike articular cartilage, disc cells (both the nucleus pulposus and the annulus fibrosus) have long, thin cytoplasmic projections that reach 30 μm or more. The function of these outgrowths remains unknown, but it is assumed that they are capable of sensing mechanical stress in tissues.

End plates They are a thin (less than 1 mm) layer of hyaline cartilage located between the vertebral body and the intervertebral disc. The collagen fibers it contains are arranged horizontally.

Intervertebral disc of a healthy person contains blood vessels and nerves only in the outer plates of the annulus fibrosus. The endplate, like any hyaline cartilage, has no vessels or nerves. Basically, the nerves travel accompanied by vessels, but they can also travel independently of them (branches of the sinuvertebral nerve, anterior and gray communicating branches). The sinuvertebral nerve is the recurrent meningeal branch of the spinal nerve. This nerve leaves the spinal ganglion and enters the intervertebral foramen, where it divides into ascending and descending branches.

As has been shown in animals, the sensory fibers of the sinuvertebral nerve are formed by fibers from both the anterior and posterior roots. It should be noted that the anterior longitudinal ligament is innervated by branches of the spinal ganglion. The posterior longitudinal ligament receives nociceptive innervation from the ascending branches of the sinuvertebral nerve, which also innervates the outer plates of the annulus fibrosus.

With age, there is a gradual blurring of the boundary between the fibrous ring and the nucleus pulposus, which becomes more and more fibrotic. Over time, the disc becomes morphologically less structured - the annular plates of the annulus fibrosus change (merge, bifurcate), collagen and elastic fibers are located more and more chaotically. Cracks often form, especially in the nucleus pulposus. Degeneration processes are also observed in the blood vessels and nerves of the disc. Fragmented cell proliferation occurs (especially in the nucleus pulposus). Over time, intervertebral disc cells die. Thus, in an adult, the number of cellular elements decreases by almost 2 times. It should be noted that degenerative changes in the intervertebral disc (cell death, fragmented cell proliferation, fragmentation of the nucleus pulposus, changes in the annulus fibrosus), the severity of which is determined by a person’s age, is quite difficult to differentiate from those changes that would be interpreted as “pathological”.

The mechanical properties (and accordingly the function) of the intervertebral disc are ensured intercellular matrix, the main components of which are collagen and aggrecan (proteoglycan). The collagen network is formed by type I and type II collagen fibers, which constitute approximately 70% and 20% of the dry weight of the entire disc, respectively. Collagen fibers provide strength to the disc and fix it to the vertebral bodies. Aggrecan (the main disc proteoglycan), composed of chondroitin and keratan sulfate, provides hydration to the disc. Thus, the weight of proteoglycans and water in the annulus fibrosus is 5 and 70%, and in the nucleus pulposus – 15 and 80%, respectively. Synthetic and lytic (proteinases) processes constantly occur in the intercellular matrix. However, it is a histologically constant structure, which provides mechanical strength to the intervertebral disc. Despite the morphological similarity with articular cartilage, the intervertebral disc has a number of differences. Thus, protein glycans (aggrecan) of the disc contain a higher content of keratan sulfate. In addition, in the same person, disc aggrecans are smaller and have more pronounced degenerative changes than articular cartilage aggrecans.

Let us consider in more detail the structure of the nucleus pulposus and the fibrous ring - the main components of the intervertebral disc.

Nucleus pulposus. According to morphological and biochemical analysis, including microscopic and ultramicroscopic studies, the nucleus pulposus of human intervertebral discs belongs to a type of cartilaginous tissue (V.T. Podorozhnaya, 1988; M.N. Pavlova, G.A. Semenova, 1989; A.M. Seidman, 1990). The characteristics of the main substance of the nucleus pulposus correspond to the physical constants of a gel containing 83-85% water. Studies by a number of scientists have determined a decrease in the content of the water fraction of the gel with age. Thus, in newborns the nucleus pulposus contains up to 90% water, in a child of 11 years old - 86%, in an adult - 80%, in people over 70 years old - 60% water (W. Wasilev, W. Kuhnel, 1992; R. Putz , 1993). The gel contains proteoglycans, which, along with water and collagen, are the few components of the nucleus pulposus. Glycosaminoglycans in proteoglycan complexes are chondroitin sulfates and, in smaller quantities, keratan sulfate. The function of the chondroitin sulfate-containing region of a proteoglycan macromolecule is to create pressure associated with the spatial structure of the macromolecule. High imbibitional pressure in the intervertebral disc retains a large number of water molecules. The hydrophilicity of proteoglycan molecules ensures their spatial separation and separation of collagen fibrils. The resistance of the nucleus pulposus to compression is determined by the hydrophilic properties of proteoglycans and is directly proportional to the amount of bound water. Compression forces, acting on the pulpous substance, increase its internal pressure. Water, being incompressible, resists compression. The keratan sulfate region is capable of interacting with collagen fibrils and their glycoprotein sheaths to form cross-links. This enhances the spatial stabilization of proteoglycans and ensures the distribution of negatively charged terminal groups of glycosaminoglycans in the tissue, which is necessary for the transport of metabolites into the nucleus pulposus. The nucleus pulposus, surrounded by a fibrous ring, occupies up to 40% of the area of ​​the intervertebral discs. It is to it that most of the forces transformed in the nucleus pulposus are distributed.

Fibrous ring formed by fibrous plates, which are located concentrically around the nucleus pulposus and are separated by a thin layer of matrix or layers of loose connective tissue. The number of plates varies from 10 to 24 (W.C. Horton, 1958). In the anterior part of the fibrous ring the number of plates reaches 22-24, and in the posterior part it decreases to 8-10 (A.A. Burukhin, 1983; K.L. Markolf, 1974). The plates of the anterior sections of the fibrous ring are located almost vertically, and the rear ones have the form of an arc, the convexity of which is directed posteriorly. The thickness of the anterior plates reaches 600 microns, the rear ones - 40 microns (N.N. Sak, 1991). The plates consist of bundles of densely packed collagen fibers of varying thickness from 70 nm or more (T.I. Pogozheva, 1985). Their arrangement is ordered and strictly oriented. The bundles of collagen fibers in the plates are biaxially oriented relative to the longitudinal axis of the spine at an angle of 120° (A. Peacock, 1952). The collagen fibers of the outer plates of the annulus fibrosus are woven into the deep fibers of the lateral longitudinal ligament of the spine. The fibers of the outer plates of the fibrous ring are attached to the bodies of adjacent vertebrae in the region of the marginal border - the limbus, and are also embedded in the bone tissue in the form of Sharpey fibers and fuse tightly with the bone. The fibrils of the internal plates of the annulus fibrosus are woven into the fibers of hyaline cartilage, separating the tissue of the intervertebral disc from the spongy bone of the vertebral bodies. This is how a “closed package” is formed, which closes the nucleus pulposus into a continuous fibrous frame between the fibrous ring along the periphery and the hyaline plates connected above and below by a single system of fibers. In the plates of the outer layers of the annulus fibrosus, alternating differently oriented fibers with different densities were identified: loosely packed ones alternate with densely packed ones. In dense layers, the fibers split and move into loosely packed layers, thus creating a single system of fibers. The loose layers are filled with tissue fluid and, being an elastic shock-absorbing tissue between dense layers, provide elasticity to the fibrous ring. The loose fibrous part of the annulus fibrosus is represented by thin, unoriented collagen and elastic fibers and a ground substance consisting mainly of chondroitin-4-6-sulfate and hyaluronic acid.

The height of the discs and spine is not constant throughout the day. After a night's rest, their height increases, and by the end of the day it decreases. The daily fluctuation in the length of the spine reaches 2 cm. The deformation of the intervertebral discs varies with compression and tension. If, when compressed, the disks flatten by 1-2 mm, then when stretched, their height increases by 3-5 mm.

Normally, there is a physiological protrusion of the disc, which is that the outer edge of the fibrous ring, under the action of an axial load, protrudes beyond the line connecting the edges of adjacent vertebrae. This protrusion of the posterior edge of the disc towards the spinal canal is clearly visible on myelograms and alignment. usually, does not exceed 3 mm . Physiological protrusion of the disc increases with extension of the spine, disappears or decreases with flexion.

Pathological protrusion of the intervertebral disc differs from physiological the fact that widespread or local protrusion of the fibrous ring leads to a narrowing of the spinal canal and does not decrease with movements of the spine. Let's move on to consider the pathology of the intervertebral disc.

PATHOLOGY ( addition)

The main element of intervertebral disc degeneration is decrease in the number of protein glycans. Fragmentation of aggrecans and loss of glycosaminoglycans occur, which leads to a drop in osmotic pressure and, as a consequence, dehydration of the disc. However, even in degenerated discs, cells retain the ability to produce normal aggrecans.

Compared to protein glycans, the collagen composition of the disc changes to a lesser extent. Thus, the absolute amount of collagen in the disc, as a rule, does not change. However, redistribution of different types of collagen fibers is possible. In addition, the process of collagen denaturation occurs. However, by analogy with protein glycans, disc cell elements retain the ability to synthesize healthy collagen even in a degenerated intervertebral disc.

Loss of protein glycans and dehydration of the disc lead to a decrease in their shock-absorbing and supporting functions. The intervertebral discs decrease in height and gradually begin to prolapse into the spinal canal. Thus, improper redistribution of axial load on the endplates and annulus fibrosus can provoke discogenic pain. Degenerative-dystrophic changes are not limited only to the intervertebral disc, since changes in its height lead to pathological processes in neighboring formations. Thus, a decrease in the supporting function of the disc leads to overload in the facet joints, which contributes to the development of osteoarthritis and a decrease in the tension of the yellow ligaments, which leads to a decrease in their elasticity and corrugation. Disc prolapse, arthrosis of the facet joints and thickening (corrugation) of the yellow ligaments lead to spinal stenosis.

It has now been proven that compression of the root by an intervertebral hernia is not the only cause of radicular pain, since about 70% of people do not experience pain when the roots are compressed by a hernial protrusion. It is believed that in some cases, when a herniated disc comes into contact with a root, sensitization of the latter occurs due to aseptic (autoimmune) inflammation, the source of which is the cells of the affected disc.

One of the main causes of intervertebral disc degeneration is violation of adequate nutrition of its cellular elements. In vitro, it was shown that intervertebral disc cells are quite sensitive to oxygen deficiency, glucose and pH changes. Impaired cell function leads to changes in the composition of the intercellular matrix, which triggers and/or accelerates degenerative processes in the disc. Nutrition of the cells of the intervertebral disc occurs indirectly, since the blood vessels are located from them at a distance of up to 8 mm (capillaries of the vertebral bodies and outer plates of the fibrous ring.

Disk power failure can be due to many reasons: various anemias, atherosclerosis. In addition, metabolic disorders are observed with overload and insufficient load on the intervertebral disc. It is believed that in these cases there is a restructuring of the capillaries of the vertebral bodies and/or compaction of the endplates, which impedes the diffusion of nutrients. However, it should be noted that the degenerative process is associated only with incorrect execution of movements during physical activity, while their correct execution increases the intradiscal content of protein glycans.

There are several stages of degenerative-dystrophic changes in the intervertebral disc:
stage 0 - the disk is not modified
stage 1 - small tears of the inner 1/3 of the annular plates of the annulus fibrosus
stage 2 - significant destruction of the disc occurs, but the outer rings of the annulus fibrosus are preserved, which prevent herniation; there is no compression of the roots; at this stage, in addition to back pain, it may radiate to the legs to the level of the knee joint
stage 3 - cracks and tears are observed along the entire radius of the fibrous ring; the disc prolapses, causing tears of the posterior longitudinal ligament

Currently, this classification has been slightly modified, since it did not include compression syndromes.

Attempts to create a real classification, based on computed tomography data, began in 1990 and ended in 1996 (Schellhas):
stage 0 - the contrast agent injected into the center of the disc does not leave the boundaries of the nucleus pulposus
stage 1 - at this stage the contrast penetrates to the inner 1/3 of the annulus fibrosus
stage 2 - contrast extends to 2/3 of the annulus fibrosus
stage 3 - crack along the entire radius of the fibrous ring; the contrast penetrates to the outer plates of the fibrous ring; it is believed that pain occurs at this stage, since only the outer layers of the disc are innervated
stage 4 - there is a spread of contrast around the circumference (reminiscent of an anchor), but no more than 30°; this is due to the fact that radial discontinuities merge with concentric ones
stage 5 - contrast penetration into the epidural space occurs; Apparently, this provokes aseptic (autoimmune) inflammation in nearby soft tissues, which sometimes causes radiculopathy even without obvious signs of compression

Comparative anatomy data allow us to consider the intervertebral disc as articular cartilage, both components of which - the nucleus pulposus (pulpous) and the fibrous ring - are currently classified as fibrous cartilage, and the endplates of the vertebral bodies are likened to articular surfaces. The results of pathomorphological and histochemical studies made it possible to classify degenerative changes in the intervertebral disc as a multifactorial process. Disc degeneration is based on a genetic defect. Several genes responsible for the strength and quality of osteochondral structures have been identified: genes for the synthesis of type 9 collagen, aggrecan, vitamin D receptor, metalloproteinase. Genetic “breakage” is systemic in nature, which is confirmed by the high prevalence of intervertebral disc degeneration in patients with osteoarthritis. The trigger point for the development of degenerative changes in the disc is structural damage to the fibrous ring due to inadequate physical activity. The ineffectiveness of reparative processes in the intervertebral disc leads to an increase in degenerative changes and the appearance of pain. Normally, the posterior outer layers of the annulus fibrosus (1–3 mm) and the adjacent posterior longitudinal ligament are equipped with nociceptors. It has been proven that in a structurally changed disc, nociceptors penetrate the anterior part of the annulus fibrosus and nucleus pulposus, increasing the density of the nociceptive field. In vivo, nociceptor stimulation is supported not only by mechanical stress, but also by inflammation. A degeneratively altered disc produces pro-inflammatory cytokines IL-1, IL-6, IL-8, as well as TNF (tumor necrosis factor). Researchers emphasize that the contact of elements of the nucleus pulposus with nociceptors on the periphery of the annulus fibrosus helps to lower the threshold of excitability of nerve endings and increase their perception of pain. It is believed that the intervertebral disc is most associated with pain - at the stage of disc prolapse, with a decrease in its height, with the appearance of radial cracks in the fibrous ring. When intervertebral disc degeneration leads to herniation, a root or nerve becomes an additional cause of pain. Inflammatory agents produced by hernia cells increase the sensitivity of the root to mechanical pressure. Changes in pain threshold play an important role in the development of chronic pain.

Attempts have been made to identify the mechanisms of discogenic pain using discography. It has been shown that pain occurs with the introduction of substances like glycosaminoglycans and lactic acid, with compression of the roots, with hyperflexion of the facet joints. It has been suggested that the endplates may be the source of pain. Ohnmeiss in 1997 showed that complete rupture of the annulus fibrosus or disc herniation is not necessary for the occurrence of leg pain. He proved that even at stage 2 (when the outer plates of the annulus fibrosus remain intact), pain in the lower back occurs, radiating to the leg. It has now been proven that pain from one level can also come from underlying segments, for example, pathology of the L4–L5 disc can cause pain in the L2 dermatome.

The formation of pain syndrome during intervertebral disc herniation is influenced by:
violation of the biomechanics of the motor act
violation of posture and balance of the muscular-ligamentous-fascial apparatus
imbalance between the anterior and posterior muscle girdle
imbalances in the sacroiliac joints and other pelvic structures

It should be noted that the severity of clinical manifestations of intervertebral disc herniation is also due to the ratio of the size of the intervertebral hernia to the size of the spinal canal where the spinal cord and its roots are located. A favorable ratio is a small hernia (from 4 to 7 mm) and a wide spinal canal (up to 20 mm). And the lower this indicator, the less favorable the course of the disease, requiring a longer course of treatment.

In the case of an association of clinical manifestations of vertebral pathology with degenerative changes in the intervertebral disc, the term used in foreign literature is - "degenerative disc disease"- DBD (degenerative disk disease - DDD). DBD is a component of a single process – osteoarthritis of the spine.

Stages of formation of herniated intervertebral discs according to Decolux A.P. (1984):
protruding disk- bulging of the intervertebral disc, which has lost its elastic properties, into the spinal canal
failed disc- disc masses are located in the intervertebral space and compress the contents of the spinal canal through the intact posterior longitudinal ligament
prolapsed disc - most often detected in acute or traumatic hernia; partial prolapse of intervertebral disc masses into the spinal canal accompanying rupture of the posterior longitudinal ligament; direct compression of the spinal cord and roots
free sequestered disc- a disc lying loosely in the cavity of the spinal canal (in acute cases or as a result of trauma, it may be accompanied by a rupture of the meninges and intradural location of hernial masses

Most often in the lumbosacral spine, hernias occur in the intervertebral discs at the level of L5-S1 (48% of the total number of hernias at the lumbosacral level) and at the level of L4-L5 (46%). Less commonly, they are localized at the level of L3-L4 (5%) and most rarely at the level of L2-L3 (less than 1%).

Anatomical classification of disc herniations:
simple disc herniation , in which the posterior longitudinal ligament is torn, and a larger or smaller portion of the disc, as well as the nucleus pulposus, protrudes into the spinal canal; can be in two forms:
- free disc herniation due to “breaking”: the contents of the disc pass through the posterior longitudinal ligament, but still remain partially attached to areas of the intervertebral disc that have not yet prolapsed or to the corresponding vertebral plane;
- wandering hernia– has no connection with the intervertebral space and moves freely in the spinal canal;
intermittent disc herniation - occurs from an unusually strong mechanical load or from strong compression exerted on the spine, with its subsequent return to its original position after the load is removed, although the nucleus pulposus may remain permanently dislocated.

Topographic classification of disc herniation:
intraspinal disc herniation – completely located in the spinal canal and emanating from the middle part of the disc, this hernia can be in three positions:
- in the dorsal medial(Stukey group I) causes compression of the spinal cord or cauda equina;
- paramdial (group II according to Stukey) causes unilateral or bilateral compression of the spinal cord;
- dosolateral(Stukey group III) compresses the spinal cord or intraspinal nerve roots, or the lateral part of the vertebral plate on one or both sides; this is the most common form, since at this level there is a weak zone in the disc - the posterior longitudinal ligament is reduced to several fibers located on the lateral parts;
disc herniation located inside the intervertebral foramen , comes from the outer part of the disc and compresses the corresponding root towards the articular process;
lateral disc herniation comes from the most lateral part of the disc and can cause various symptoms, provided it is located in the lower part of the cervical segment, compressing the vertebral artery and vertebral nerve;
ventral disc herniation , emanating from the ventral edge, does not give any symptoms and is therefore of no interest.

According to the direction of prolapse of the sequestrum, hernias are divided into (Handbook of Vertebroneurology, Kuznetsov V.F. 2000):
anterolateral, which are located outside the anterior semicircle of the vertebral bodies, peel off or perforate the anterior longitudinal ligament, can cause sympathalgic syndrome when the paravertebral sympathetic chain is involved in the process;
posterolateral, which pierce the posterior half of the fibrous ring:
- median hernias – in the midline;
- paramedian – close to the midline;
- lateral hernias(foraminal) - on the side of the midline (from the posterior longitudinal ligament).

Sometimes two or more types of disc herniations are combined. ABOUT vertebral body hernia (Schmorl's hernia) cm. .

Intervertebral disc degeneration is visualized by magnetic resonance imaging (MRI). The stages of disc degeneration are described (D. Schlenska et al.):
M0 – norm; nucleus pulposus spherical or ovoid in shape
M1 – loal (segmental) decrease in the degree of luminescence
M2 – disc degeneration; disappearance of the glow of the nucleus pulposus

Types (stages) of vertebral body lesions associated with intervertebral disc degeneration, according to MRI data:
Type 1 – a decrease in signal intensity on T1-weighted images and an increase in signal intensity on T2-weighted images indicate inflammatory processes in the bone marrow of the vertebrae
Type 2 - an increase in signal intensity on T1 and T2-weighted images indicates the replacement of normal bone marrow with adipose tissue
Type 3 - a decrease in signal intensity on T1 and T2 - weighted images indicates processes of osteosclerosis

The main diagnostic criteria for intervertebral disc herniation are:
the presence of vertebrogenic syndrome, manifested by pain, limited mobility and deformities (antalgic scoliosis) in the affected part of the spine; tonic tension of the paravertebral muscles
sensory disorders in the area of ​​the neurometamere of the affected root
motor disturbances in the muscles innervated by the affected root
decreased or lost reflexes
the presence of relatively deep biomechanical disturbances in motor compensation
data from computed tomography (CT), magnetic resonance imaging (MRI) or radiographic examination, verifying the pathology of the intervertebral disc, spinal canal and intervertebral foramina
data from electroneurophysiological studies (F-wave, H-reflex, somatosensory evoked potentials, transcranial magnetic stimulation), recording conduction disturbances along the root, as well as the results of needle electromyography with analysis of action potentials of motor units, allowing to establish the presence of denervation changes in the muscles of the affected myotome

Clinical significance of the size of protrusions and herniations of the intervertebral disc:
cervical section of the spinal column:
1-2 mm- small protrusion size
3-4 mm- average protrusion size(urgent outpatient treatment required)
5-6 mm- (outpatient treatment is still possible)
6-7 mm and more- large size of intervertebral hernia(requires surgical treatment)
lumbar and thoracic sections of the spinal column:
1-5 mm- small protrusion size(outpatient treatment is required, treatment at home is possible: spinal traction and special gymnastics)
6-8 mm- average size of intervertebral hernia(outpatient treatment required, surgical treatment not indicated)
9-12 mm- large size of intervertebral hernia(urgent outpatient treatment is required, surgical treatment only for symptoms of compression of the spinal cord and elements of the cauda equina)
more than 12 mm- large prolapse or sequestered hernia(outpatient treatment is possible, but on the condition that if symptoms of compression of the spinal cord and elements of the cauda equina appear, the patient has the opportunity to undergo surgery the next day; with symptoms of spinal cord compression and a number of MRI signs, immediate surgical treatment is required)

Note: when the spinal canal is narrowed, a smaller intervertebral hernia behaves like a larger one.

There is such a rule, What disc bulge is considered severe and clinically significant if it exceeds 25% anteroposterior diameter of the spinal canal (according to other authors - if it exceeds 15% anteroposterior diameter of the spinal canal) or narrows the canal to a critical level 10 mm.

Periodization of compression manifestations of spinal osteochondrosis against the background of intervertebral disc herniation:
acute period (stage of exudative inflammation) - duration 5-7 days; the hernial protrusion swells - the swelling reaches a maximum on days 3-5, increases in size, compressing the contents of the epidural space, including the roots, the vessels that feed them, as well as the vertebral venous plexus; sometimes the hernial sac ruptures and its contents spill into the epidural space, leading to the development of reactive epiduritis or down along the posterior longitudinal ligament; pain gradually increases; any movement causes unbearable suffering; The first night is especially difficult for patients; the main question that needs to be resolved in this situation is whether or not the patient needs urgent surgical intervention; absolute indications for surgery are: myeloschaemia or spinal stroke; reactive epiduritis; compression of two or more roots along the length; pelvic disorders
subacute period(2-3 weeks) - the exudative phase of inflammation is replaced by a productive one; adhesions gradually form around the hernia, which deform the epidural space, compress the roots, and sometimes fix them to the surrounding ligaments and membranes
early recovery period- 4-6 weeks
late recovery period(6 weeks - six months) - the most unpredictable period; the patient feels healthy, but the disc has not yet healed; To avoid unpleasant consequences, during any physical activity it is recommended to wear a fixation belt

To characterize the degree of disc protrusion, contradictory terms are used: “disc herniation”, “ disc protrusion", "disc prolapse". Some authors use them almost as synonyms. Others suggest using the term “disc protrusion” to refer to the initial stage of disc protrusion, when the nucleus pulposus has not yet broken through the outer layers of the annulus fibrosus, the term “disc herniation” only when the nucleus pulposus or its fragments have broken through the outer layers of the annulus fibrosus, and the term “disc prolapse” only refers to the prolapse of hernial material that has lost its connection with the disc into the spinal canal. Still others propose to distinguish between intrusions, in which the outer layers of the annulus fibrosus remain intact, and extrusions, in which the hernial material breaks through the outer layers of the annulus fibrosus and the posterior longitudinal ligament into the spinal canna.

Russian authors(Magomedov M.K., Golovatenko-Abramov K.V., 2003), based on the use of Latin roots in term formation, suggest the use of the following terms:
“protrusion” (prolapse) – protrusion of the intervertebral disc beyond the vertebral bodies due to stretching of the fibrous ring without significant ruptures. At the same time, the authors point out that protrusion and prolapse are identical concepts and can be used as synonyms;
“extrusion” - protrusion of the disc caused by rupture of the FC and the release of part of the nucleus pulposus through the resulting defect, but maintaining the integrity of the posterior longitudinal ligament;
“true hernia”, in which not only the fibrous ring, but also the posterior longitudinal ligament ruptures.

Japanese authors(Matsui Y., Maeda M., Nakagami W. et al., 1998; Takashi I., Takafumi N., Tarou K. et al., 1996) distinguish four types of hernial protrusions, using the following terms to designate them:
“protrusion" (P-type, P-type) - protrusion of the disc in which there is no rupture of the fibrous ring or (if present) does not extend to its outer parts;
« subligamentous extrusion"(SE-type, SE-type) - a hernia in which perforation of the fibrous ring occurs while preserving the posterior longitudinal ligament;
« transligamentous extrusion"(TE-type, TE-type) - a hernia that ruptures not only the fibrous ring, but also the posterior longitudinal ligament;
“sequestration” (C-type, S-type) – a hernia in which part of the nucleus pulposus ruptures the posterior longitudinal ligament and is sequestered in the epidural space.

Swedish authors(Jonsson B., Stromqvist B., 1996; Jonsson B., Jonsson R., Stromqvist B., 1998) there are two main types of hernial protrusions - so-called contained hernias and noncontained hernias. The first group includes: “protrusion” - a protrusion in which ruptures of the fibrous ring are absent or minimally expressed; and “prolapse” - dislocation of the material of the nucleus pulposus to the posterior longitudinal ligament with complete or almost complete rupture of the fibrous ring. The second group of hernial protrusions is represented by extrusion and sequestration. During extrusion, the posterior longitudinal ligament is ruptured, but the fallen fragment of the nucleus pulposus remains connected to the rest of it, in contrast to sequestration, in which this fragment separates and becomes free.

One of the most clear schemes was proposed by J. McCulloch and E. Transfeldt (1997), who distinguish:
1) disc protrusion– as the initial stage of disc herniation, in which all disc structures, including the annulus fibrosus, are displaced beyond the line connecting the edges of two adjacent vertebrae, but the outer layers of the annulus fibrosus remain intact, the material of the nucleus pulposus can penetrate into the inner layers of the annulus fibrosus (intrusion);
2) subannular (subligamentary) extrusion , in which the damaged nucleus plosus or its fragments are squeezed out through a crack in the annulus fibrosus, but do not break through the outermost fibers of the annulus fibrosus and the posterior longitudinal ligament, although they can move up or down in relation to the disc;
3) transannular (transligamentary) extrusion , in which the nucleus pulposus or its fragments break through the outer fibers of the annulus fibrosus and/or the posterior longitudinal ligament, but maintain connection with the disc;
4) prolapse (loss) , characterized by sequestration of the hernia with loss of connection with the remaining disc material and prolapse into the spinal canal.

A review of the terminology of disc herniations would not be complete without noting that, according to a number of authors, the term “ disc herniation» can be used when the displacement of the disc material occupies less than 50% of its circumference. In this case, the hernia can be local (focal), if it occupies up to 25% of the disc circumference, or diffuse, occupying 25-50%. A protrusion of more than 50% of the disc circumference is not a hernia, but is called “ disc bulging"(bulging disk).

To overcome the terminological confusion, they propose (a team of authors from the Department of Neurology of the Russian Medical Academy of Postgraduate Education: Doctor of Medical Sciences, Professor V.N. Shtok; Doctor of Medical Sciences, Professor O.S. Levin; Candidate of Medical Sciences Associate Professor B.A. Borisov, Yu.V. Pavlov; Candidate of Medical Sciences I. G. Smolentseva; Doctor of Medical Sciences, Professor N.V. Fedorova) when formulating a diagnosis, use only one term - “ disc herniation» . In this case, a “disc herniation” can be understood as any protrusion of the edge of the disc beyond the line connecting the edges of adjacent vertebrae, which exceeds physiological limits (normally no more than 2-3 mm).

To clarify the degree of disc herniation, the same team of authors (employees of the Department of Neurology of the Russian Medical Academy of Postgraduate Education: Doctor of Medical Sciences, Professor V.N. Shtok; Doctor of Medical Sciences, Professor O.S. Levin; Candidate of Medical Sciences Scientific Associate Professor B.A. Borisov, Yu.V. Pavlov; Candidate of Medical Sciences I.G. Smolentseva; Doctor of Medical Sciences, Professor N.V. Fedorova) propose the following scheme:
I degree– slight protrusion of the fibrous ring without displacement of the posterior longitudinal ligament;
II degree– medium-sized protrusion of the fibrous ring. occupying no more than two-thirds of the anterior epidural space;
III degree– a large disc herniation that displaces the spinal cord and dural sac posteriorly;
IV degree– massive disc herniation. compressing the spinal cord or dural sac.

!!! It should be emphasized that the presence of tension symptoms, radicular symptoms, and local pain does not necessarily indicate that a disc herniation is the cause of the pain syndrome. Diagnosis of a disc herniation as the cause of a neurological syndrome is possible only when the clinical picture corresponds to the level and degree of disc protrusion.

The spinal cord is a section of the central nervous system of the spine, which is a cord 45 cm long and 1 cm wide.

Structure of the spinal cord

The spinal cord is located in the spinal canal. Behind and in front there are two grooves, thanks to which the brain is divided into right and left halves. It is covered with three membranes: vascular, arachnoid and hard. The space between the choroid and arachnoid membranes is filled with cerebrospinal fluid.

In the center of the spinal cord you can see gray matter, shaped like a butterfly when cut through. Gray matter consists of motor and interneurons. The outer layer of the brain is white matter of axons collected in descending and ascending pathways.

There are two types of horns in the gray matter: anterior, which contains motor neurons, and posterior, where interneurons are located.

The structure of the spinal cord has 31 segments. From each of them extend the anterior and posterior roots, which, merging, form the spinal nerve. When they leave the brain, the nerves immediately split into roots - posterior and anterior. The dorsal roots are formed with the help of axons of afferent neurons and they are directed into the dorsal horns of the gray matter. At this point they form synapses with efferent neurons, whose axons form the anterior roots of the spinal nerves.

The dorsal roots contain the spinal nodes, which contain sensory nerve cells.

The spinal canal runs through the center of the spinal cord. To the muscles of the head, lungs, heart, thoracic organs and upper extremities, nerves arise from segments of the upper thoracic and cervical parts of the brain. The abdominal organs and trunk muscles are controlled by the lumbar and thoracic segments. The muscles of the lower abdominal cavity and the muscles of the lower extremities are controlled by the sacral and lower lumbar segments of the brain.

Functions of the spinal cord

There are two main functions of the spinal cord:

• Conductor;
• Reflex.

The conductor function is that nerve impulses move along the ascending pathways of the brain to the brain, and commands are sent through the descending pathways from the brain to the working organs.

The reflex function of the spinal cord is that it allows you to perform the simplest reflexes (knee reflex, withdrawal of the hand, flexion and extension of the upper and lower extremities, etc.).

Only simple motor reflexes are carried out under the control of the spinal cord. All other movements, such as walking, running, etc., require the participation of the brain.

Spinal cord pathologies

Based on the causes of spinal cord pathologies, three groups of spinal cord diseases can be distinguished:

• Developmental defects – postnatal or congenital abnormalities in the structure of the brain;
• Diseases caused by tumors, neuroinfections, spinal circulatory disorders, hereditary diseases of the nervous system;
• Spinal cord injuries, which include bruises and fractures, compression, concussions, dislocations and hemorrhages. They can appear either independently or in combination with other factors.

Any disease of the spinal cord has very serious consequences. A special type of disease includes spinal cord injuries, which, according to statistics, can be divided into three groups:

• Car accidents are the most common cause of spinal cord injury. Driving motorcycles is especially dangerous because there is no backrest to protect the spine.
• A fall from a height can be either accidental or intentional. In any case, the risk of spinal cord damage is quite high. Often athletes, fans of extreme sports and jumping from heights get injured in this way.
• Everyday and extraordinary injuries. They often occur as a result of going down and falling in the wrong place, falling down the stairs or when there is ice. This group also includes knife and bullet wounds and many other cases.

With spinal cord injuries, the conduction function is primarily disrupted, which leads to very disastrous consequences. For example, damage to the brain in the cervical region leads to the fact that brain functions are preserved, but they lose connections with most organs and muscles of the body, which leads to paralysis of the body. The same disorders occur when peripheral nerves are damaged. If the sensory nerves are damaged, sensation in certain areas of the body is impaired, and damage to the motor nerves impairs the movement of certain muscles.

Most nerves are of a mixed nature, and their damage causes both the inability to move and loss of sensation.

Spinal cord puncture

A spinal puncture involves inserting a special needle into the subarachnoid space. A puncture of the spinal cord is performed in special laboratories, where the patency of this organ is determined and the pressure of the cerebrospinal fluid is measured. The puncture is performed for both therapeutic and diagnostic purposes. It allows you to timely diagnose the presence of hemorrhage and its intensity, find inflammatory processes in the meninges, determine the nature of the stroke, and determine changes in the nature of the cerebrospinal fluid, signaling diseases of the central nervous system.

Often a puncture is performed to administer radiopaque and medicinal fluids.

For therapeutic purposes, a puncture is performed to extract blood or purulent fluid, as well as to administer antibiotics and antiseptics.

Indications for spinal cord puncture:

• Meningoencephalitis;
• Unexpected hemorrhages in the subarachnoid space due to rupture of an aneurysm;
• Cysticercosis;
• Myelitis;
• Meningitis;
• Neurosyphilis;
• Traumatic brain injury;
• Liquororrhea;
• Echinococcosis.

Sometimes, during brain surgery, spinal cord puncture is used to reduce intracranial pressure parameters, as well as to facilitate access to malignant neoplasms.