Herniated disc is characterized by displacement of the nucleus pulposus (inner part) of the intervertebral disc that can press the spinal cord or the root of a nerve (for example the sciatic nerve ). 
It is the consequence of the rupture of the external part of the disc that is located between the vertebrae. 
With regard to hernia, the size is not proportional to the symptoms, in fact a small hernia causes the same symptoms as a large one.

A hernia of the sub-ligament type can cause much more problems than a complete extrusion. The common vertebral ligament is the last obstacle encountered by the nucleus pulposus before it irritates the nerve structures behind the vertebrae. 
The vertebral sinus nerve that innervates the third outer ring is the one that transmits the pain of the disc type.

The difference between hernia and protrusion is: 
1. In the hernia the ring is also broken in the outer part and the nucleus pulposus leaves completely of the disc, 
2. In the protrusion the ring is affected only in the innermost position and the whole disc expands to or external.

The hernias are divided according to the location:

  • Central, the most frequent;
  • Postero-lateral;
  • Foraminal;
  • Extraforaminal, the rarest;
  • Subligamentar;
  • Transligamentar.

The hernia causes an inflammation with exudate that causes several phenomena:

  • Vasodilatation, characterized by redness and heat;
  • Altering the permeability of blood vessels, endothelial cells allow leakage due to endothelial injury or because of chemical mediators.
  • Liquid, proteins, white blood cells and red blood cells leave the circulation due to increased osmotic and hydrostatic pressure inside the blood vessels;
  • Vascular stasis is a deceleration of circulation with vasodilation to allow chemical mediators and inflammatory cells to respond to the stimulus.

The nucleus pulposus appears as a foreign body to the immune system; in fact, under normal circumstances it is not innervated and vascularized. 
When the ring fissures and the nuclear substance contacts the capillaries, the immune system reacts as if it had found a harmful body and reacts causing inflammation, in fact releases mast cells, histamine, IgG antibodies and neuropeptides. 
This reaction causes destruction and absorption of the nucleus from the part of macrophages. 
When a protrusion or disc herniation occurs, the cytokines responsible for inflammation that come in contact with the adjacent nerve root and cause root pain are released, this process is important because root pain can occur even without a herniated disc.
The anterior disc herniation will lengthen the anterior common vertebral ligament and generally does not cause symptoms.


Causes of Herniated Disc

The herniated disc can be caused by the natural aging of the spine . 
In children and young people discs have a high water content. As we age, the discs begin to dry out and weaken. The discs begin to shrink and the spaces between the vertebrae become narrower. 
Ordinary people speak of “crushed vertebrae” to describe this phenomenon related to arthrosis of the spine . 
This normal aging process is called disc degeneration.


Risk factors

In addition to the wear and tear caused by aging, other factors can increase the likelihood of a herniated disc.

  • Genre. Men between the ages of 30 and 50 are more likely to develop a hernia.
  • Poor posture of the spine. Using the back muscles to lift heavy objects without bending the knee can cause a herniated disc because of the strong pressure exerted on the intervertebral discs.
  • Weight. Excess weight adds tension to the spine disks.
  • Repetitive activities that strain the spine.
  • Many jobs are physically demanding, some require continuous lifting, bending or twisting.
  • Driving for long periods. Vibrations put pressure on the spine and discs.
  • Sedentary lifestyle. Regular exercise is important in preventing many diseases, including a herniated disc.
  • Smoking. It is believed that cigarette smoke reduces the oxygen supply to the disc and causes faster degeneration.
  • The cervical hernia can be caused by accidents that cause whiplash or other trauma .


Symptoms of lumbar disc herniation

For most people with a herniated disc, spinal pain is the initial symptom. 
The pain can last for a few days and then it improves. 

The symptoms can be as follows:

This may indicate a more serious problem called equine tail syndrome. 
This disease is caused by compression of the nerve roots of the spine. Equine tail syndrome requires immediate medical attention.

Not all patients feel pain when the disc degenerates.


Symptoms of cervical disc herniation

Diagnosis of herniated disc

Medical examination
To find out if the patient suffers from a herniated disc, the doctor should visit the patient and perform neurological tests. 
To test for muscle weakness, the doctor asks to walk on the heels and toes. 
They should then examine the reflexes of the patellar tendon or Achilles tendon with the hammer and evaluate the strength of the lower limb muscles.


Main tests are:

Lasègue test for the sciatic nerve
In this test, the patient is lying on his back, the doctor lifts the stretched leg. 
If the patient feels pain in the spine and leg and is unable to reach a 60 ° angle between the leg and the bed, the test is positive.

The Néri test

Wassermann test for the crural nerve
The patient is lying on his stomach and should bend the knee of the leg that hurts. 
The doctor picks up the patient’s ankle and raises his thigh to the belly in contact with the bed. 
If you feel back and groin pain , the test is positive.

Confirmation is obtained by magnetic resonance imaging (MRI).


Medical classification of hernia

The central posterior hernia

Very rare due to the strong resistance of the posterior vertebral ligament (less than 10%), can cause different symptoms depending on the size, bilateral low back pain to the spinal block with bilateral sciatica. 
If the hernia is medium (and possibly paramedian) and very bulky, it can occupy the entire canal. 
Symptoms may worsen during bilateral tilt, the position assumed by the patient is flexion pain.

Lasègue ‘s test is positive and in some cases even the Néri test .


Postero-lateral disc herniation

It is the most frequent, herniated material compresses the inner part of the nerve root in the layer between the spinal cord exit and the conjugate foramen, it can also irritate the dural sac. 
It can cause sciatic pain but the most intense pain is at the lumbar level because the hernia causes tension of the posterior ligament of the spine that is richly innervated by the sinus vertebral nerve of luschka. 
Symptoms worsen as the spine tilts toward the healthy side, while the tilt towards the painful side releases the nerve root of the compression and relieves the pain. 
The patient tends to bend over into the pain to suffer less. 
The Lasègue test and the neonatal test are positive.

Foraminal hernia

Occurs in the conjugate foramen, compresses the nerve root and the superior null spinal ganglion: the L3-L4 level foraminal hernia presses the L3 spinal ganglion.

Represents 10% of all lumbar hernias, it is usually found between the L3 and L5 discs. 
It is usually associated with a vascular disorder, at the level of the foramen, that is, vasoconstriction and venous congestion. 
The pain along the affected nerve is due to periradicular meningeal irritation. 
The pain in the spine increases standing for a long time and is relieved when sitting down, there are no analgesic positions for the lumbar spine. 
The symptoms are severe, along the lower extremity worsen leaning over the foot on the sore side and at night, the analgesic position with the body leaning forward.

Extraforaminal hernia

Compresses the exterior of the nerve root at the level of the outlet of the conjugate foramen or affects the root above, if more side. 
The signs and symptoms are: with the paramedian hernia (external) the pain occurs in the ipsilateral inclination because it increases the compression of the disc. 
The patient tends to stay in place to attenuate the pressure pain of the herniated disc material of the nerve root. 
In case of hernia symptoms on the side the symptoms are felt with the lateral flexion of the other side and then the position of the patient will be tilted to the affected limb.

Signs and Symptoms
Pain occurs by bending toward the side of the hernia if it is external because it increases the disc’s compression, so the patient maintains a posture tilting to the other side. 
If the hernia is lateral, the pain will come down to the opposite side and the posture adopted by the patient is inclined toward the lesion. 
Lasegue test is positive with lateral hernia, but it is negative if it is external.

Subclinical hernia

It consists of a displacement of the nucleus pulposus behind or below the vertebral body, the most frequent is with the posterolateral hernia, behind the underlying vertebra. 
The hernia pushes strongly against the posterior common vertebral ligament and slides into the spinal cord, it can also push against the conjugate foramen. 
The ligament is damaged and deformed due to the thrust of the disc material, the pressure receptors are overstimulated and cause severe back pain  with muscle contraction .

Sub-ligary hernia

It irritates the nerve root and dura mater that is innervated by Luschka’s sinus nerve, which can cause a painful irradiation into the external area of ​​the pelvis. 
The patient may suffer from symptoms such as  cruralgia , ie belly pain  or in the genital area. 
Almost all movements are painful because:

  • In flexion it increases the pressure on the posterior common ligament;
  • In extension the posterior protrusion of the ring occurs;
  • The lateral slope to the opposite side of the lesion causes a thrust against the pain receptors;
  • At least one rotation causes worsening of the symptoms, depending on the location of the hernia, if it is high it will cause an increase of the pain during the contralateral rotation, while if it is low the symptoms worsen with the rotation for the injury.

Transplanted Hernia

It consists of moving the nucleus pulposus, the fibrous annulus and the posterior common ligament until it reaches the spinal canal. 
The first type is with the ligament that is not injured, the slipped material maintains the contact with the intervertebral disc, the ligament is tightly stretched allowing the extrusion of the nucleus pulposus in the epidural space. 
In the second type  the hernia is “prey”, the slipped nucleus pulposus broke the fibrous annulus and the posterior longitudinal ligament, completely separating the disc from the expulsion fragment that is placed in the spinal canal and / or conjugation foramen. 
The extruded material can be reduced in size to the autoimmune reaction of the body which, for the purpose of macrophages , cleans and dehydrates this substance.
If the hernia is associated with osteophyte can be serious because this bone proliferation can compress the nerve root and the only solution may be surgery.

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