Spinal stenosis and back pain

Stenosis of the spinal stenosis (English spinal stenosis) is the narrowing of its lumen at any level. In practical work, doctors use the classification of stenoses of the vertebral canal, based on pathogenesis and localization of stenosis.

Congenital stenosis of the spinal canal is characterized by a narrowing of its mid-sagittal diameter, i.е. The localization of stenosis is central. At the same time, with different variants of congenital pathology of the spinal canal, the narrowing of any of its divisions is possible. For acquired degenerative stenoses, most often developing with arthrosis of intervertebral joints, the narrowing of the channels of the nerve roots is typical. The nature of acquired stenoses that develop with herniated intervertebral discs depends on the zone of "loss" of the hernia, in accordance with which the hernia itself is designated as medial, mediolateral, lateral or foraminous.

Classification of spinal stenosis 

	Types of stenosis
By pathogenesis	A) Congenital and b) acquired, incl. associated with herniated disc associated with other pathologies hyperplasia of the capsule of the arcuate joints, ossification of the yellow ligament, posterior longitudinal ligament others
By localization	Central stenosis, Stenosis of nerve root canals, Foraminous stenosis (stenosis of radicular apertures)

The development of narrowing of the spinal canal can lead to a fairly wide range of diseases. RH Dorwart cites the following list of similar pathological conditions:

Diseases accompanied by stenoses of the spinal canal (according to Dorwart R., 1981) 

Types of stenosis	Diseases accompanied by stenosis
Congenital stenosis	a) idiopathic stenosis, b) achondroplasia, c) hypochondroplasia, d) mucopolysaccharidosis, e) dysplasia accompanied by weakness of the atlantoaxial joint (metatrogic epiphyseal dysplasia, spondyloepiphysary dysplasia, Knist's disease, multiple epiphyseal dysplasia, chondrodysplasia), e) Down's syndrome instability C1-C2), g) hypophosphatemic vitamin D-resistant rickets
Acquired stenosis
Degenerative	a) spondylosis and arthrosis, b) compression of the spinal canal with soft tissues, c) isolated lysis of the intervertebral disc, d) degenerative spondylolisthesis.
Combined	Combination of diseases that cause congenital and acquired stenosis, degenerative stenosis and protrusion of the intervertebral disc
In spondylolysis	a) without spondylolisthesis, b) with spondylolisthesis
Iatrogenic	a) after laminectomy, b) after arthrodesis (spondylodease)
Post-traumatic	a) in acute and b) late periods of spine trauma
In metabolic diseases	a) Paget's disease, b) epidural lipomatosis with Cushing's syndrome or long-term steroid therapy, c) acromegaly, d) fluorosis, e) pseudogout (dehydrated calcium pyrophosphate depletion disease)
Other pathological conditions	A) ankylosing spondylitis, b) kalygification or ossification of the posterior longitudinal ligament (OLLP), c) diffuse idiopathic hyperostosis, d) calcification or ossification of the yellow ligament, e) a single beginning of the lumbosacral nerve roots (relative stenosis of the spinal canal)

The greatest clinical significance is the stenosis of the spinal canal, which develop with herniated intervertebral discs. The development of hernias is characterized by a certain staging (Bersnev VP et al., 1998): Stage I - protrusion of the disk, stage II - prolapse of the pulpous nucleus and fragments of the disc in the vertebral canal (actually hernia), stage III - hidden spondylolisthesis or " slipping "disk, stage IV - stabilization or self-healing.

Despite repeated repetition in the text of terms characterizing different morphological variants of herniated intervertebral discs, it seems to us nevertheless expedient to define each of them:

• disc protrusion - displacement towards the spinal canal of the pulpous nucleus and swelling of the elements of the fibrous ring of the
  intervertebral disk into the vertebral canal without compromising the integrity of the latter;
• extrusion - swelling of the elements of the fibrous ring and degenerated pulpous nucleus into the spinal canal;
• prolapse - prolapse into the vertebral canal through the defects of the fibrous ring of fragments of the degenerated pulpous nucleus, which remain in contact with the disk;
• sequestration - displacement along the vertebral canal of the fallen fragments of the degenerated pulposus core.

To compare the different aetiology of the narrowing of the spinal canal and its individual parts, we proposed a technique for quantifying the central stenoses of the vertebral canal and narrowing the dural sac with pure congenital kyphosis and kyphosis caused by tuberculous spondylitis. The relative magnitude of stenosis of the dural sac was assessed according to myeloma (tomo) graphy or contrast tomography, and the relative value of stenosis of the vertebral canal - according to CT, transverse or mid-sagittal sections of the MRI, by echoespondilograms and lateral x-ray (tomo) grams of the spine. The relative magnitude of stenosis was determined by the formula

K = (a-b) / a x 100%,

Where a is the sagittal dimension of the subarachnoid space (vertebral canal) in the neutral zone, b is the sagittal size of the subarachnoid space (vertebral canal) at the maximum compression level. When the stenosis is localized at the level of the physiological lumbar thickening (T10-T12), the normal size of the spinal canal (dural sac) is defined as the average between the upper and lower neutral zones. Being relative values expressed as a percentage, these indicators can be used for a comparative assessment of different pathological conditions different in etiology, including in different age groups. Despite their seeming uniformity and parallelism of changes, both indicators do not substitute for each other. Thus, with tuberculous spondylitis, a combination of stenosis of the subarachnoid space with a normal or even enlarged size of the spinal canal is possible. At the same time, for vertebral deformities, the true stenosis of the vertebral canal is characteristic. In a number of cases, this sign plays a decisive role in differentiating the congenital vertebrae, which is combined with the pathology of the vertebral canal, from the consequences of the transferred inflammatory process.

The study of clinical features of diseases accompanied by slowly developing compression of the spinal canal and spinal cord (congenital kyphosis, tuberculosis spondylitis of the thoracic and thoracolumbar spine) made it possible to reveal clinically significant relative central stenosis of the dural sac (or vertebral canal), in which the vast majority of patients develop neurologic disorders - paresis and paralysis. It is empirically established that this value is 40-45%.

With acute compression, which is usually the case with spinal injuries and herniated discs, the reserve capabilities of the spinal cord are much more limited, and neurological disorders and back pain develop at significantly lower stenosis values.

[1], [2], [3], [4], [5]