The symptoms of a herniated disc arise from the partial emergence of the gelatinous core of the disc, which can press on the nerves (e.g. sciatic nerve).
This occurs as a result of an injury to the outer area of the intervertebral disc, which lies between the vertebrae.
With a herniated disc, the extent of the damage is not proportional to the symptoms; a small herniated disc produces the same symptoms as a large one
A subligamentous disc herniation is significantly more limiting than full extrusion.
The vertebral ligament is the last obstacle the gelatinous nucleus encounters before it irritates the nerve structures located behind the vertebrae.
The vertebral sinus nerve, which innervates the third outer segment of the fibrous ring, transmits disc pain.
The difference between herniated disc (prolapse) and protrusion is that in the first case the fibrous ring is also torn in its outermost area and the gelatinous core emerges completely from it; in the case of a protrusion, on the other hand, the fibrous ring is only injured in the inner area and the entire intervertebral disc is displaced outwards.
Herniated discs can be classified based on their location:
- central (most common);
- extraforaminal (least rare);
The herniated disc creates inflammation with exudate, which causes various phenomena:
- dilatation of blood vessels, characterized by redness and heat;
- Alterations in the permeability of the blood vessels that allow endothelial cells to exit due to damage to the endothelium or through the fault of messenger substances.
- Fluid, proteins, white and red blood cells leave the bloodstream because of the increase in external osmotic pressure and hydrostatic pressure in blood vessels;
- vascular stasis; the blood circulation slows down with dilation of the blood vessels to enable messenger substances and inflammatory cells to respond to the stimulus.
The gelatinous core is a foreign body for the immune system; in fact, in the normal state, it is not connected to either nerves or blood vessels.
When the ring of fibers ruptures and the core substance comes into contact with the capillaries, the immune system reacts immediately as if it has detected a pollutant and causes inflammation, releasing mast cells (mastocytes), histamine, antibodies IgG and neuropeptides.
This reaction causes the destruction and absorption of the gelatinous nucleus by the macrophages.
When the disc bulges, protrudes, or prolapses, cytokines are released that cause inflammation, contact the adjacent nerve root, and cause referred pain; this process is important because referred pain can occur without a herniated disc.
Anterior herniated disc stretches the anterior vertebral ligament and usually has no symptoms.
Causes of a herniated disc
A herniated disc can occur due to the natural aging of the spine.
In children and young people, the water content in the intervertebral disc is high. With age, the intervertebral discs lose their elasticity and become increasingly brittle. They shrink and the distance between the vertebrae becomes smaller and smaller.
This phenomenon is related to spinal arthrosis .
The normal aging process is called disc degeneration.
In addition to age, other factors can also increase the likelihood of a herniated disc.
- Gender. Men between the ages of 30 and 50 have a greater chance of developing a herniated disc.
- back deformities . When lifting heavy objects, straining the back muscles puts a lot of pressure on the discs if the knees are not bent, which can lead to a herniated disc.
- Weight. Being overweight increases the tension placed on the spinal discs.
- Repetitive activities that put stress on the spine.
- Many jobs and hobbies involve physical wear and tear with continuous lifting, pulling, bending, and twisting movements.
- Long car rides. The vibrations put pressure on the spine and intervertebral discs.
- Predominantly sedentary lifestyle. Regular physical exercise is important to prevent many diseases, including a herniated disc.
- Smoking. It is assumed that cigarette smoke reduces the oxygen supply to the intervertebral disc and accelerates the degeneration process.
- A herniated disc in the cervical spine can result from traffic accidents that cause whiplash or other injuries.
Symptoms of a herniated disc in the lumbar spine
The first symptom of a herniated disc is usually back pain.
The pain may last for a few days and then subside.
In general, the following symptoms can occur:
- back pain ,
- leg and/or foot pain (sciatica),
- numbness or tingling in the legs and/or feet,
- feeling of weakness in the legs and/or feet,
- loss of sensitivity and reflexes along the sciatic or femoral nerve,
- Loss of bladder or bowel control (extremely rare). This can indicate a serious problem called cauda equina syndrome. This condition is caused by pinching of the spinal nerve roots and requires immediate medical attention.
The degeneration of the intervertebral disc does not necessarily have to cause pain.
Symptoms of a herniated disc in the cervical spine
- neck pain ,
- Pain in the arm and hand ( cervicobrachialgia ) ,
- numbness or tingling in the fingers ,
- weakness in the arms and/or hands,
- Loss of sensitivity and reflexes along the cervical nerves.
To find out if a herniated disc is present, the doctor must examine the patient and perform neurological tests.
To check for muscle weakness, the doctor will ask the patient to walk on heels and tiptoes.
Then the reflexes of the patellar ligament and Achilles tendon are tested with the help of a small hammer and the muscle strength of the entire lower limb is assessed.
The most important tests include:
Lasègue test for the sciatic nerve
Here the patient lies on his back and the doctor lifts the straight leg.
If the patient feels pain in the back and leg and the leg cannot be raised enough to create a 60° angle between the leg and the table, the test is positive.
Wassermann test for the femoral nerve
The patient lies on his stomach and has to bend the knee of the painful leg.
The physician grasps the patient’s ankle and raises the leg, keeping the abdomen in contact with the table.
With pain in the back and groin, the test is positive.
The suspected diagnosis is confirmed with magnetic resonance imaging (MRI).
Herniated disc in posterior middle position
Occurs very rarely, in less than 10% of cases, thanks to the high resistance of the posterior vertebral ligament; Symptoms vary by size, ranging from bilateral lombalgia to spinal fusion with bilateral sciatica .
A herniated disc that occurs in the middle and is very voluminous can occupy the entire spinal canal.
Symptoms may worsen with tilting to either side, the patient adopts a stooped posture to avoid pain.
The Lasègue test is positive, in some cases also the Neri test
Herniated disc in posterior lateral position
This is the most common case, the herniated disc material presses against the inner area of the nerve root at the level of the dural sac exit and intervertebral foramen; the dural sac itself can also become irritated.
This herniated disc can cause unilateral sciatica, but the most severe pain occurs in the lumbar region because the disc puts tension on the posterior vertebral ligament, which is amply innervated by Luschka’s vertebral sinus nerve.
Symptoms worsen when the back is bent to the healthy side, while bending to the painful side relieves pressure on the nerve root and the pain subsides.
The patient will assume a relieving posture bent over the pain in order to reduce the suffering.
Lasègue and Neri’s tests are positive.
Foraminal Disc Herniation
It occurs in the intervertebral foramen, presses on nerve roots and overlying dorsal ganglion: the foraminal disc herniation at position L3-L4 presses on the L3 dorsal ganglion.
It accounts for approximately 10% of all lumbar disc herniations and usually occurs in the L3 to L5 region.
It is usually also associated with vascular disorders at the level of the vertebral foramen, ie vasoconstriction and venous congestion.
Pain along the affected nerve is due to meningeal-periradicular irritation.
Lower back pain worsens with prolonged standing, relieves with sitting, but there is no resting position for the back.
Symptoms are severe, worsening along the lower limbs when weight is placed on the foot on the painful side, at night the relieving position is a hunched body.
Extraforaminal disc herniation
The outer part of the nerve root is compressed at the level of the exit from the intervertebral foramen or – in the case of a more lateral position – the overlying root is affected.
Signs and symptoms: in paramedian disc herniation (external), the pain occurs with homolateral inclination because the pressure on the disc increases; the patient assumes an opposite relieving posture in order to relieve the pressure of the disc material from the nerve root.
In the case of a lateral herniated disc, the symptoms are felt when bending to the opposite side, so the relieving posture is on the affected side.
Signs and Symptoms:
Pain is felt when bending the body to the side of the herniated disc (if it is external) because the compression of the disc increases; the patient will bend the body to the opposite side to avoid pain.
If the herniation is lateral, the pain will be felt when bending to the opposite side, so the patient will lean toward the affected side to relieve the pain.
The Lasègue test is positive for a lateral disc herniation and negative for an external position.
Subligamentous disc herniation
It consists in displacement of the gelatinous nucleus behind or below the vertebral body; the most common is the postero-inferior ejection, i.e. behind the underlying vertebrae.
The disc presses hard against the posterior vertebral ligament and protrudes into the spinal canal; it can also push into the intervertebral foramen.
The ligament is not damaged, only deformed by the thrust of the disc material. The pressure receptors are overstimulated and cause severe back pain (lombalgia) with muscle contracture; the patient will adopt a relieving posture.
If the ejection (extrusion) is medial, the venous plexus located behind the ligament at the dura mater is compressed, causing venous congestion and localized inflammation.
The periligamentous arterioles and those of the dura mater are irritated, the vascular baro-receptors are stimulated and produce alterations in vascular activity.
Disorders of blood circulation are followed by a drop in pH and stimulation of nociceptors (pain receptors), which causes back pain.
The compression effect may also occur in the anterior region of the dura mater, which is innervated by Luschka’s vertebral sinus nerve; the meningeal syndrome that follows may radiate upwards or downwards, at the level of the abdomen or perineum, like cruralgia.
Lateral subligamentous disc herniation
Nerve root and dura mater, which is innervated by Luschka’s vertebral sinus nerve, become irritated, which can cause painful radiating to the external pelvis.
A foraminal inflammation develops, which leads to a decrease in pH, ie local acidosis, which causes the release of algogenic substances.
In the second phase, pressure on the process can cause nerve conduction disorders and radiculopathy due to inflammation from anoxia.
The symptoms manifest themselves as functional limitations: difficulty putting on shoes, walking, etc.; the pain may affect the abdominal or genital area.
The patient may complain of the symptoms of lumbocruralgia , such as abdominal and genital pain.
The relieving position can be on the side of the herniated disc to close the tear from which the core material emerges and thus relieve the pressure on the posterior vertebral ligament; or the patient leans toward the sound side to unload more of the weight on the posterior condyle and less on the disc.
Almost all movements are painful:
- when bending, the pressure on the posterior longitudinal ligament increases;
- when stretched, the posterior protrusion of the fibrous ring is felt;
- a lateral bend to the healthy side causes a push against the pain receptors;
- rotation aggravates symptoms depending on the location of the herniated disc; if it is high, turning toward the painful side increases pain; if it is low, turning toward the injured side increases pain.
Transligamentous disc herniation
Here the gelatinous core is pushed out of the fibrous ring beyond the rear longitudinal ligament into the spinal canal.
In the first case , the ligament is not damaged, the contact between the leaked material and the intervertebral disc remains; the ligament is severely overstretched, allowing extrusion of the gelatinous nucleus into the anterior epidural area.
These types of injuries, larger than the disc, have a good chance of being absorbed over time; typically a 50% reduction in extrusion size is recorded.
In some patients, the symptoms of disc extrusion resolve without changes in the size of the herniated disc.
The suspected factors contributing to absorption are new blood vessel formation (angiogenesis) and fibroblast growth.
As with subligamentous disc herniation, homolateral rotation pain occurs when the disc herniation occurs at the top of the hole, with rotation to the opposite side alleviating symptoms, the gelatinous core has emerged and is pressing against the ligamentous receptors of Luschka’s vertebral sinus nerve.
If turning to the healthy side causes pain, the herniated disc is located lower down and the vertebral ligament is pressed against the disc when the back rotates.
The second case is a “ sequestered” disc herniation; the extruded gelatinous core has torn both the annulus and the posterior longitudinal ligament, completely separating the disc from the extruded fragment, which is positioned in the spinal canal and/or intervertebral foramen.
Injury to the tissues causes pain because they stimulate the nociceptors.
At the level of the exit from the intervertebral foramen and in the lateral area of the dural sac, great pressure can arise on the nerve root.
A sequestered (extruded) gelatinous core can prove very painful; if it occurs in a central position, it can also cause incontinence, ie cauda equina syndrome.
The expelled material can become depleted by an autoimmune reaction of the body, which uses macrophages to clean and dehydrate this substance.
If the herniated disc is linked to an osteophyte, a serious clinical picture can result if the bony prominence compresses the nerve root, which would require surgical intervention.
- Herniated disc surgery
- Cervicobrachialgia and herniated disc of the cervical spine
- Symptoms of whiplash