During protrusion, the inner fibers of the fibrocartilage ring rupture and the gelatinous core pushes into these cracks.
The whole intervertebral disc shifts evenly and symmetrically from its anatomical position, causing narrowing of the spinal canal and flattening at the front of the dural sac.
The vertebral longitudinal ligament is abundantly innervated with the nociceptive fibers of Luschka’s vertebral sinus nerve.
The gelatinous nucleus pushes into the posterior area of the fibrous ring, the fibers supplied by Luschka’s vertebral sinus nerve are overstretched; in this case, the posterior vertebral ligament is not affected.
The patient complains of acute, very severe pain, and a contracture is formed on the same side.
Violation of fibers leads to the release of kinins and prostaglandin in the damaged area; these are nociceptive, i.e. pain-causing molecules that stimulate the C receptors of the fibers, which then transmit the pain signal to the brain.
What are the symptoms of intervertebral disc protrusion
Protrusion is classified based on the fissure width of the fibrous ring; at the first degree, the innermost fibers rupture and the intervertebral disc bulges beyond the fibrous ring (its outer circumference) into the anterior epidural region.
In this condition, the patient is symptom-free.
Intervertebral disc protrusion becomes painful and symptomatic from the third degree, i.e. when the gelatinous nucleus penetrates almost to the outermost area of the fibrous ring, which protrudes to the outer circumference of the vertebral body without stretching the posterior ligament.
The third degree produces lombalgia (low back pain) and sciatica.
For medical examination, about 75% of patients appear in a relieving posture, bent to the side opposite to the pain, the tear in the fibrous ring expands and the gelatinous core shifts, bringing the posterior vertebral ligament into a less painful position.
This protective position leads to an expansion of the fibrous ring rupture and reduces the pressure on the nociceptors (pain receptors).
The remaining 25% of patients bend to the painful side and support allows widening of the hernia, reducing disc pressure.
Bending and stretching movements produce pain due to the contraction of the paravertebral muscles; lateral inclination and rotation are symptomatic to the side opposite the restraining position.
Bulging of the intervertebral disc
A bulging of the intervertebral disc is present when the gelatinous core of the intervertebral disc loses fluid (dehydrates) and the disc height thus decreases; the fibrocartilage ring surrounding the core expands outwards, like a compressed jam bun.
It is an asymtomatic disorder.
The pain can last for weeks and spread to the sacroiliac joint (sacrum-iliac joint), gluteal muscles and the upper and posterior thigh area.
The human body reacts with phagocytosis or absorption of the torn ring fibers.
Most affected are young people and middle-aged adults.
The patient may feel symptoms on the back, but these are not caused by bulging; During the day he is doing relatively well and can also carry out sports activities.
The nocturnal water intake of the intervertebral disc leads to an increase in its volume. When standing up, gravity increases the hydrostatic pressure and pushes the gelatinous core outwards.
The intervertebral disc hernia
Due to a traumatic event or wrong movement, the innermost fibers of the fibrocartilage ring can rupture, triggering an autoimmune reaction of the body.
The patient complains of pain in the lumbar region and possibly in the lower limb, which intensifies with movement.
Muscle elastics are formed.
The symptoms are not neurological, the tests for sciatica nerve and crural nerve are negative.
X-rays and TC show no damage.
The intervertebral disc is a fibrocartilaginous structure located between two vertebral bodies. It represents a very important part of the spine and forms the joint between the two vertebral bodies.
The size depends on their position in the spine; the intervertebral discs in the lumbar region are higher than those in the cervical section.
In the lumbar region, the ratio of vertebral body and disc height is greater than in the cervical/thoracic spine.
The intervertebral discs of the cervical and lumbar vertebrae are wider at the front than at the back, they adapt exactly to the shape of the bone and are completely complementary, because the vertebra are double-concave and the intervertebral disc double-convex.
The indoor area is called the gelatinous nucleus (nucleus pulposus) because of its high fluid content and its central position; the outer lining, on the other hand, is called the fibrous ring (annulus fibrosus), as it has a tendon-like consistency; a healthy, hydrated disc has a higher strength than the surrounding bone.
A vertebra consists of vertebral bodies, spinous and transverse processes; the latter are not burdened by body weight, but have the function of protecting the nerve structures and limiting rotational movement, while promoting flexion and stretching movement.
Tasks of the intervertebral disc:
- bearing body weight and transferring it to the underlying vertebra;
- form a support point for movements in the lumbar/sacrum region of the back;
- Cohesion of the vertebral bodies.
The gelatinous core consists of 2/3 of proteoglycans, which are proteins that bind to disaccharides of hyaluronic acid residues and form a complex that has the essential ability to absorb amounts of water 400 to 500 times greater than their weight.
This property makes the intervertebral disc act like a sponge. The presence of the liquid portion in the intervertebral disc allows the distribution of body weight over the entire lower surface of the intervertebral disc. When the spine is bent forward, the fluid shifts to the back of the intervertebral disc and increases the internal pressure and load-bearing capacity, otherwise the weight would be completely discharged in the front area.
The nucleus has a consistency like gelatin or toothpaste, is not connected to blood vessels, and thus food intake from the external structures to the fibrous ring is carried out by osmosis.
In addition to the proteoglycans, the gelatinous core also consists of collagenous connective tissue fibers and a small proportion of elastin.
The core pressure is very high because it must continuously push the fibers of the surrounding ring outwards to avoid pressing the ring.
The fibrocartilage ring consists of 20 collagen layers that are connected by chemical compounds of the proteoglycans.
The fibers of a layer are arranged in opposite directions with respect to the adjacent layers; thanks to this structure, the fibrous ring has a high resistance to any vortex movement, but is susceptible to the formation of cracks and fissures.
The outer layers surround the intervertebral disc, are coupled to the vertebral bodies above and below and have an enormous load resistance, especially with loads coming from above.
The fibrous ring consists of 2/3 water, as well as proteoglycans, collagen and elastin.
The vertebral cartilage envelops the underlying and overlying area of each vertebral body, has a thickness of about 3 millimeters and is a strip that connects bone and intervertebral disc; its task is to promote the sliding movement of the two structures, as well as to supply the fibrous ring and gelatinous core with nutrients.
The outer area of the intervertebral disc has no contact with the cartilage, but directly with the vertebra; this is where the most stretchable disc fibers run; the inner layers, on the other hand, act as a capsule of the gelatinous core.
The vertebral cartilage located on the surface is fibrous cartilage, in the lower areas hyaline cartilage.
Luschka’s vertebral sinus nerve is a mixed nerve with a sentient and an autonomic section; it originates from the anterior spinal cord root and runs between the posterior vertebral margin and the dura mater.
One of its most important characteristics is that it can transmit the pain signal from the following areas:
- from the third outer and posterior segment of the intervertebral disc,
- from the posterior longitudinal ligament,
- from the posterior part of the vertebral body,
- from the arteries of the intervertebral hole,
- from the intermediate mandrel process tape,
- from the facet joints,
- from the deep muscles.
The component of Luschka’s vertebral sinus nerve, which belongs to the sympathetic nervous system, controls vascular motor function (vascular constriction and vasodilation).
The metabolism of the intervertebral disc
The supply of nutrients to the intervertebral disc occurs by diffusion through the capillaries of the subchondral bone area of the overloving vertebra; from there, the nutrients reach the cartilage, which then supplies the gelatinous core and fibrous ring.
The elimination of catabolic waste products and the absorption of necessary substances such as oxygen and energy substances depend very much on the nocturnal hydration of the intervertebral disc; the intervertebral disc can absorb a lot of water, especially at night, because it benefits from weightlessness.
Degeneration of the intervertebral disc is closely linked to hypotension of the abdominal and back muscles.
The degeneration of the intervertebral disc is symptom-free in the majority of patients, but a small minority complains of chronic back pain in the lumbar region (spondylarthrosis).
In magnetic resonance, in well-hydrated tissue, the space between two vertebrae is black on the outside and white or grey on the inside; if the tissue is completely dried out, the NMR shows only a black line.
The aging of the intervertebral disc has the following causes:
- Idiopathic origin with decreasing number of blood vessels that provide blood circulation to the cartilage; this leads to a reduced number of molecules that bind to the proteoglycans of the intervertebral disc for water absorption.
The result is a reduced pressure on the gelatinous core, which thus cannot distribute the body weight evenly; in addition, the weight rests on the fiber ring, which is not intended for this function.
- Chemical degradation of collagen on the outside of the fibrous ring.
- fissures of the vertebral cartilage or fibers of the fibrous ring; with sufficient hydration, the outer fibers of the intervertebral disc are directed convex outwards and the middle part pushes outwards; with dehydration, the intervertebral disc becomes deformed and tends to collapse inwards. The first structure to break is the cartilage, then possibly the fibers of the fibrous ring.
- Schmorl nodules are intervertebral disc hernias in which the gelatinous nucleus penetrates the subchondral layer and settles on the side near the bone, causing the intervertebral disc to lose height. Causes for this are, for example, falling on the sacrum or coccyx, lifting heavy loads, etc.
- Genetic predisposition; those who have parents who suffer from this disorder are likely to develop the aging of the internal disc structure themselves.
- work-related; there are professional groups that favor the appearance.
- Smoking damages the capillary blood vessels that supply blood to the cartilage, so less oxygen and nutrients arrive.
The biomechanics of the spine
When the intervertebral disc is loaded from above, the weight presses on the vertebral cartilage and to the outside of the fibrous ring; pressing against the cartilage can cause a Schmorl disc rupture.
In a degenerated intervertebral disc, the body weight is transferred to the underlying vertebra only through the Fasser ring, the gelatinous core can not bear any loads.
When bending, the anterior part of the intervertebral disc must be compressed and moved forward; the core shifts backwards and the posterior fibers of the fiber ring expand due to the experienced elongation.
In the lumbar region, the most extensive movements are bending forward and to the side, the most mobile vertebra is L3.
Of utmost importance is the posture that is taken during the day, because the pressure on the intervertebral disc increases when bending forward and takes on excessive proportions when holding a weight in the hands.
To facilitate the spine when sitting, a correct sitting position is important; To do this, adopt a natural hollow cross position and support the elbows on the armrests to take the load off the upper body.
Bending forward and to the side are the movements that enormously increase the compression of the intervertebral disc in approximately equal parts.
The movements of the vertebrae are often combined, but their behavior changes depending on whether the spine is in a neutral position or bent forward (flexion) or stretched backwards (extension).
From a neutral position (straight back), the rotation of the vertebra to one side always causes lateral flexion to the opposite side (rotation to the right and tilt to the left).
When moving from an inflection or extension position, the behavior is exactly the opposite, i.e. when turning to the left, an automatic inflection to the same side occurs (Fryette’s law).
The disc damage
About 80% of people without back pain have at least one disc protrusion of the lumbar spine; They are artificially positive.
Only 40% of patients with chronic back pain (lombalgia).
or radiating pain to the lower limb has a posterior disc protrusion.
An overload when bending or a trauma such as a fall from a height causes first a fissure in the cartilage coating and then the overstretching and tearing of the ring fibers.
When the tear in the fibrous ring expands from the gelatinous nucleus to the outside of the intervertebral disc, inflammation develops in the body, which increases the intensity of pain.
An acute attack of back pain or contracture of the paravertebral muscles can be caused by the entry of the inflammatory fluid into the gelatinous nucleus; in this way, the outer fibers of the intervertebral disc are irritated and the classic disc pain occurs.
Edema does not have the classic symptoms of protrusion: loss of sensitivity, strength and reflexes, pain throughout the leg, tingling in the foot.
According to the Dallas classification, at the 1st degree of intervertebral disc overstretching, the injury of the first ring fiber layer occurs; a greater overstretching can reach the 6th degree, whereby the substance of the gelatinous core emerges from the fibrous ring.
What can be done? Therapy for protrusion and bulging of the intervertebral disc
Physical therapy can be helpful in reducing the pressure that the disc exerts on the nerve and reducing inflammation, especially the McKenzie Method helps here.
Osteopathy belongs to the manual therapies and can relieve joint blockages and muscle tension and moderate nerve compressions.
Allowed sports are swimming and cycling without gradients; Running should be avoided.
Pharmacological treatment With intervertebral disc bulging, prevention in the form of postural gymnastics is the best treatment
Protrusion of the intervertebral disc can provoke severe sciatica or mild discomfort in the lumbar region.
In case of pain in the back and legs, restriction of movement, tingling and loss of sensitivity, various therapy options are available to the doctor.
Pharmacological treatment includes oral use of cortisone-containing medications, injections of anti-inflammatory painkillers (NSAIDs) and muscle relaxants (e.g., Voltaren or MuscoRil), ozone therapy or cortisone injections.
If conservative treatment shows insufficient effect, the doctor may advise surgery.
How long does the pain last? The prognosis for recovery
Acute inflammation lasts about 2-3 days, if the pain persists, appropriate treatment must be given.
In most cases, the pain caused by protrusion in the lumbar region passes within a month; if the cervical spine is affected, healing can also take place faster.
If the symptoms persist for more than 3-6 months, the doctor may recommend surgical intervention.