Mechanisms of disc degeneration
Structural changes are based on biomechanical disorders. Constant load on the degenerating disc alters the distribution of dynamic forces, which inevitably leads to a decrease in the height of the intervertebral space.
- Intravertebral hernias: form when the hyaline cartilage plate is damaged. Disc tissue is pressed into the spongy substance of the vertebral body.
- Osteophytes: occur as a reaction to chronic bone irritation. In osteochondrosis, these are dense outgrowths of compact bone tissue directed perpendicularly to the axis of the spine.
Formation of pain syndromes
Pain syndrome in osteochondrosis has a complex nature and includes several interrelated mechanisms:
- Reflex syndromes. Caused by pathological impulses from affected tissues (posterior longitudinal ligament, annulus fibrosus, periosteum). Impulses travel along the posterior root, switch in the spinal cord horns, and provoke a response — a musculotonic, visceral, or vasomotor reflex. Prolonged impulses lead to neuroosteofibrosis — dystrophy of ligaments and tendons.
- Compression syndromes. Associated with mechanical pressure on spinal canal structures. Root compression leads to radiculopathy, spinal cord compression to myelopathy, and compression of nourishing vessels to radiculomyelitischemia. Causes can include herniated discs, osteophytes, or displaced vertebrae.
- Myoadaptive syndromes. Secondary muscle changes due to forced spinal deformity against the background of pain.
Features of cervical osteochondrosis
Degeneration in the cervical region produces a specific clinical picture divided into several syndromes:
- Cervical discalgia: intense neck pain that worsens with head turns (often after sleep). Accompanied by muscle tension and limited mobility.
- Anterior scalene muscle syndrome: the tense muscle compresses the neurovascular bundle (brachial plexus, subclavian vessels). Causes brachialgia (arm pain) and vascular disorders (cyanosis, coldness of the extremity).
- Vertebral artery syndrome: compression of the artery in the canal of the transverse processes of C1–C6. Manifests as a headache (from the back of the head to the temples) due to insufficient blood supply, triggered by sudden movements.
- Referred pain syndromes: scapulohumeral periarthritis (with possible shoulder contracture) and epicondylitis (pain in the humeral epicondyles).
Diagnostic Principles
The basis of diagnosis is the detection of biomechanical, sensory, and motor disorders corresponding to the level of the lesion. For example, root tension signs (Lasegue's, Wassermann's) are used to assess compression.
Radiological imaging has evolved from simple radiographs to high-precision tomographies:
- Radiography (including functional flexion/extension views) shows endplate sclerosis, osteophytes, and segmental instability.
- CT and MRI are modern standards of early diagnosis. CT clearly shows disc degeneration and bone structures, while MRI visualizes the spinal cord, nerve roots, and the degree of compression of the dural sac and vessels in detail.
- Contrast methods (myelography, discography) are outdated because they show only the level of compression, but not its character.
Briefly: answers to topical questions
Which tension signs are used to assess spinal nerve root compression?
Tension signs are used to assess spinal nerve root compression, allowing determination of the severity of the compression syndrome.
- Lasegue's sign — appearance of pain when lifting a fully straightened leg and its disappearance when flexing the leg at the knee.
- Crossed Lasegue's sign (Bechterew's sign) — occurrence of pain on the affected side when lifting the healthy leg.
- Charnley's sign — used to assess the degree of compression.
- Wassermann's sign — used to assess the degree of compression.
- Bonnet's sign — used to assess the degree of compression.
What stages of intervertebral disc degeneration are distinguished in the pathogenesis of osteochondrosis?
Five stages of intervertebral disc degeneration are distinguished in the pathogenesis of osteochondrosis, evaluated using MRI on T2-weighted images.
| Grade | Disc structure | Signal intensity | Border of annulus and nucleus | Disc height |
|---|---|---|---|---|
| I | homogeneous | hyperintense (white) | distinct | normal |
| II | non-homogeneous | hyperintense (white) | distinct | normal |
| III | non-homogeneous | intermediate (gray) | indistinct | normal or slightly reduced |
| IV | non-homogeneous | intermediate (gray) | absent | normal or moderately reduced |
| V | non-homogeneous | hypointense (black) | absent | sharply reduced |
What clinical manifestations are characteristic of vertebral artery syndrome?
Vertebral artery syndrome is characterized by neurological brain disorders associated with blood supply insufficiency in the vertebrobasilar basin.
- Headache — radiating from the back of the head to the parietotemporal region.
- Triggering factor — sudden movements in the spine.
- Pathogenesis — compression of the vertebral artery in the bone canal formed by the transverse processes of the C1–C6 vertebrae.
Class and exam questions
What is the difference between radiculopathy and myelopathy?
Radiculopathy occurs when spinal nerve roots are compressed, while myelopathy occurs when the spinal cord itself is compressed. Both syndromes belong to compression syndromes.
Which nerve provides sensation to the structures of the spinal column?
This is the recurrent meningeal branch, or the sinuvertebral nerve of Luschka. It branches off from the spinal ganglion and returns inside the spinal canal.
Why is functional radiography needed?
It is performed in extreme flexion and extension positions. This makes it possible to detect instability of the spinal segments and joint subluxations.
What else to study on this topic
- Clinical tests (Lasègue, Charnley, Wasserman, and Bonnet signs)
- Electrophysiological methods (EMG, SSEP) in assessing conductivity
- Differential diagnosis of frozen shoulder (scapulohumeral periarthritis)
- Vasomotor and autonomic disorders in radicular syndrome
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