Slipped Disc

When discs are out of position.

A 'slipped disc' can be taken at face value. This however means a lot of patients are misled: This is because a 'slipped disc' does not describe an „occurrence“, i.e. an event. No, a 'slipped disc' means primarily that in visual terms the disc has a prolapsed appearance. I.e. it is pushed outwards. It protrudes – and therefore as a consequence may possibly also gets damaged.

Discs are the spine's shock absorbers. They feel like a wine gum or a squid ring: soft and elastic. Externally they have a firm skin but inside they are composed of a gel or jelly-like, viscous mass and a cell nucleus.

The loss of elasticity makes the disc protrude.

When a 'slipped disc' occurs there is disc protrusion, which can press on the nerve canal.

Because of their structure, discs are extremely flexible, cushioning impacts in the spine and ensuring that the individual vertebrae do not rub against each other – because this causes severe pain.

A healthy and young disc is elastic and springs back into shape from every distortion. But over time the disc loses water and forfeits its elasticity. With impacts it is pressed flat and remains in this altered shape. Since the firm external skin has a weak area close to the vertebral canal, the jelly-like contents frequently shifts in the direction of the spinal canal. The disc therefore bulges outwards. If this 'bulge' presses on the nerves which are located in the spinal canal, this produces pain, feelings of numbness and symptoms of paralysis – the classic 'slipped disc'.



An intervertebral disc lies between two adjacent vertebrae. Disc herniation is a condition in which a tear in the annulus fibrosus (Outer firmer ring) of an intervertebral disc  allows the soft, central portion (nucleus pulposus) to bulge out. Due to that adjacent neural structures may get compressed and produce symptoms of radiculopathy.

Lumbar followed by cervical spine are most commonly affected by disc herniation with former being more common than latter. L4-L5 and L5-S1 discs most common to herniate in lumbar spine. In cervical spine C5-C6 and C6-C7 discs are most commonly involved. Thoracic disc herniation is rare.Most disc herniations occur in young people. With age nucleus pulposus dries and the risk of herniation is reduced.

It is now being recognized in addition to compression of the nerve root there is release of inflammatory mediator with herniation of disc. This meditor is recognized as tumor necrosis factor-alpha (TNF). This molecule is released  not only by the herniated disc, but also in cases of disc tear, by facet joints, and in spinal stenosis.


Cause

Usually there is a history of strain on the back which may be in form of lifting heavy weights or sudden movement. In some patients no cause or antecedent event could be elicited.

A preexisting protrusion of the disc might be there before the herniation takes place. A protrusion is one in which fibers of annulus fibrosus are not torn but on increase in internal pressure it bulges out.

Minor back pain and chronic back tiredness is an indicator of general wear and tear that makes one susceptible to herniation on the occurrence of a traumatic event from bending  or a traumatic injury from a fall.

Clinical Presentation

The symptoms and presentation depend on the region involved. In cervical disc herniation the pain may occur in region of the skull, the neck, shoulder girdle, scapula, shoulder, arm, and hand.Lumbar disc can present with the pain in the lower back, buttocks, thigh, and may radiate into the foot and/or toe. The sciatic nerve is the most commonly affected  but he femoral nerve can also be affected.

The severity of symptoms may range from little or no pain to severe and unrelenting back pain that will radiate into the regions of affected nerve roots. It may be accompanied by neural deficits.

These symptoms occur in one side of the body when disc is on lateral aspect which is the most common type. In some cases however the disc is central and may cause involvement of more than one nerve roots on either side of the body. These central discs also present with bladder and bowel involvement ( Urinary incontinence) and  requires urgent removal by surgery.

Diagnosis

Diagnosis is based on the history, symptoms, and physical examination. Straight leg test test is frequently performed in the physical examination of lumbar disc though the specificity of the test is not that good.

Investigations and Imaging

X-ray

Plain X-rays have limited role in diagnosis of disc herniation as they are unable ot define soft tissues such as discs, muscles, and nerves. But  they are still used to rule out  other diseases like tumors, infections, etc.

MRI

Magnetic resonance imaging is the best investigation to confirm the disc pathologies. It can show the spinal cord, nerve roots, and surrounding areas and is very sensitive investigation to show even slight bulge of the disc.

Treatment

Contrary to the perception the majority of herniated discs can be managed with non operative treatment.

Follwing treatment modalities may be used in conjunction to treat disc herniation non operatively.

  • Physical therapy, which may include ultrasound, massage, conditioning, and exercise programs
  • Non-steroidal anti-inflammatory drugs
  • Oral steroids
  • Epidural steroid injection
  • Lumbosacral back support

Operative Treatment

If non operative methods fail, surgery should be considered. However there are certain conditions where surgery is indicated without considering option of non operative treatment

  • Significant neurological deficit
  • Cauda equina syndrome [It is a medical emergency]

Note: A recent study has found that  1-year outcomes were similar for patients assigned to early surgery and those assigned to conservative treatment with eventual surgery if needed, but the rates of pain relief and of perceived recovery were faster for those assigned to early surgery. Thus patient decision and pain tolerance become important part of surgical decision.

Surgical goals include relief of nerve compression, allowing the nerve to recover, as well as the relief of associated back pain and restoration of normal function.

Surgical options include employed are

For lumbar spine

  • Chemonucleolysis
  • Intradiscal electrothermal annuloplasty
  • Discectomy/Microdiscectomy
  • Laminectomy /Hemilaminectomy
  • Nucleoplasty
  • Disc replacement

For Cervical spine

  • Anterior cervical discectomy and fusion (for cervical disc herniation)
  • Disc arthroplasty

Stem cells are being investigated for their potential role in treatment of disc herniation.

What is a disc herniation?

Disc herniation is a broad term describing specific changes in a lumbar disc.

First, the disc itself needs to be addressed. A disc is the structure between the lumbar vertebral bodies (bones). The disc acts as a pad or cushion for the bone. The outer portion of the disc is made up of a tough fibro-cartilage matrix (the annulus) that is cross-linked in three different directions. In the middle, there is a gelatinous nucleus. (Some people describe the disc structure as resembling a jelly donut.) The disc allows for movement of the vertebral bodies and provides a buffer for compression between the bones. Normally, this system works very well.

When a disc herniates, however, there has been a tear in the outer annulus, and the gelatinous center comes out through the tear. These herniations are described by their size, as follows: bulge (small), protrusion (slightly larger), extrusion (big) and a sequestered fragment (when some of the material has broken off from the disc). Once the disc has left its original anatomical position, the disc itself can be painful, it might irritate a nerve, or it may contribute to narrowing of the spinal canal.

What is meant by a slipped disc?

A slipped is the consequence of damage to an intervertebral disc. And damage to the disc comes from age-related wear and tear which can be accelerated by overexertion or abnormal postures of the spine. If a part of the disc, because it is damaged, bulges in the direction of the spinal canal or the disc even ruptures, then its content escapes into the spinal canal. In both cases this is called a 'slipped disc'. The disc protrudes forwards or backwards &ndash, usually in the direction of the spinal canal towards where the spinal nerves run.

Anatomy of the intervertebral disc.

The disc consists of a viscous nucleus and a firm fibrous ring ('annulus'). The most frequent point of rupture is where the spinal cord and spinal nerves run.

Discs are the spine's shock absorbers. They consist of a firm outer layer which is filled with a jelly-like viscous contents and a firm nucleus. The outer layer is like an onion and consists of several fibrous layers. Therefore it is called a ;'fibrous ring';. An anterior and posterior longitudinal ligament borders on the fibrous ring. The longitudinal ligament separates the intervertebral disc from the spinal canal.

The older we become the more discs continue to lose fluid forfeiting elasticity and flexibility – similar to a sponge drying out in the sun. A moist sponge is flexible and always returns to its original shape. A dry sponge is brittle, non-elastic and when pressed retains its shape.

Therefore discs too when they have less water content and are pressed more forcefully together – are no longer able to return to their original shape. Overall they lose height.


From damage to intervertebral discs to a slipped disc.

If the disc dries out slowly the fibrous ring develops fissures. These develop primarily in the area adjoining the spinal canal through which the nerve paths run in the vertebral column. Parts of the soft, jelly-like contents of the disc may escape into these fissures of the fibrous ring. The disc slowly changes shape and bulges in the direction of the spinal canal. This status is the precursor to a slipped disc.

If the external skin ruptures completely because of the resultant pressure, a hole develops in the fibrous ring. The the jelly-like contents and even possibly the firm nucleus escape into the spinal canal. This can cause the nerves in the spinal canal to become compressed. In this case patients complain about symptoms of paralysis. Then a doctor must be consulted immediately.


Different types of slipped discs.

Different forms of slipped disc can be distinguished:

  • Bulging disc (med.: Intervertebral disc protrusion): The disc bulges but the fibrous ring remains intact
  • Slipped disc (med.: Prolapsed disc): Disc tissue escapes through the fibrous ring
  • separated slipped disc (med.: sequestered prolapsed disc): Disc tissue breaks through the longitudinal ligament and escapes through the fibrous ring into the spinal canal
  • separated slipped disc with release of a fragment (med.: subligamentous prolapsed disc with sequestration): The disc ruptures the posterior longitudinal ligament. Fragments of tissue break away and escape into the spinal canal.
The most frequent type of slipped disc.

Slipped discs are diagnosed most frequently – around 80-85% in the lumbar spine region. This is where the spine is put under the most stress. The cervical spine therefore which only has to bear 5 to 6 kilos accounts for only 10-15% of all slipped discs. The least common type of slipped discs are those in the thoracic spine. Here, the thoracic spine is stabilised by the rib cage and barely moves.


What are the signs of a slipped disc?
Radiating back pain. Symptoms of a slipped disc

If the discs in your back slip, your back will hurt. Pain can spread from your lower back into your legs.

Back pain – most patients with slipped discs come to us with this explicit symptom. Every slipped disc is associated with pain in the back and/or pain that spreads to other parts of the body. Frequently sensory disturbances or paralysis occur in the legs and feet. Depending on the area of the spine affected back pain can be located in the neck or lower back. The thoracic spine region is seldom affected.

The pain can radiate into arms and legs.

Symptoms of a slipped disc in the lumbar spine.

The main symptoms of a slipped disc in the lumbar spine are pain in the lower back. This can travel into one or both legs and subside when the leg is bent. Usually a patient with a slipped disc in the lumbar spine can barely raise his/her leg when it is extended, because this movement increases the pain. The same applies for coughing, sneezing and compression.


Symptoms of a slipped disc in the cervical spine.

A symptom of a slipped disc in the cervical spine is neck pain. This can occur on one side or on both. Frequently it travels into the shoulder or between the shoulder blades. Here hardening of the muscles can develop which really need to be protected from forceful movements which will trigger pain. Patients with a slipped disc in the cervical spine also frequently complain about headaches and dizziness.


Warning symptoms: Paralysis and numbness.

If the nerves in the spinal canal of the vertebral column are strongly compressed or have been been damaged extensively, the sensation of pain is less. At the same time distinct areas in the arms and legs can be affected by feelings of numbness. Therefore subsiding pain with progressive paralysis are an alarm signal: The pain-conducting fibres of the disc are then already destroyed. If there is central stenosis of the vertebral canal then disturbances in gait or even paraplegia may occur.

You should then immediately consult a doctor if you have feelings of numbness or symptoms of paralysis. This includes disturbances in the urge to urinate or defaecate.


What factors lead to a slipped disc?

A slipped disc develops from long years of damage to the intervertebral discs. Such damage to intervertebral discs is a phenomenon of wear and tear. Like everything that is used on a daily basis, over time there are signs of overuse. Wear and tear can however be accelerated by one-sided weight-bearing or a weakness in the body's musculature. Damage to intervertebral discs is a genetically pre-programmed condition and generally runs in the family.


Overload, lack of exercise, weak muscles.

Wear on the discs are the cause of a herniated disc. Poor posture and overuse can promote wear.

Lack of exercise, poor posture, heavy load or overweight are unfavorable factors. Truck drivers or construction workers use their back, for example, particularly strong and often take a stooped posture and thus a wrong attitude. If heavy objects are lifted incorrectly, an acute herniated disc can be triggered. Another reason for a herniated disc are also weak back muscles, because strong muscles relieve the spine and help to prevent incorrect loading of the intervertebral discs. Occasionally, a herniated disc also develops during pregnancy.

Most frequently, herniated discs occur in the lumbar spine.


I have an MRI report that says I have 3 herniated discs.  What does that mean?

There are two parts to this answer -- first, it is quite common to have disc herniations in the lumbar spine. In studies looking at people without back pain, a large percentage have had disc herniations that do not cause their back or leg to hurt.

Second, the term “disc herniations” is very broad. “Herniation” is a good – if broad – term to describe a change in the disc. In many ways, it is as generic as saying you drive “a car”. But that car can be a compact car, a sedan, a station wagon, or a large one. The same goes for disc herniations -- they can be disc bulges, protrusions, extrusions, or sequestered fragments. As they get bigger, they involve more symptoms.   

I have back pain and an MRI showing a disc has herniated.  Do I need surgery?

There are four reasons to seek a surgical solution:

Cauda Equina Syndrome, a disorder affecting a bundle of spinal nerve roots, which is extremely rare and requires urgent surgery. This syndrome includes back and leg pain, weakness and numbness, and may be associated with problems with bladder and bowel function.

 

Progressive strength loss. Many people have some strength loss, but if it is worsening, this would be an indication for surgery.

 

Intractable pain. If your pain cannot be controlled with medicine, injections, or therapy, then this too would be an indication for surgery.

 

Failure of conservative care. If a comprehensive program of physical therapy, medication, and/or injections has failed, then you might be a candidate for surgery. 

What happens to my disc herniation if I don’t have surgery? 

Patients with different sized herniations (bulges, protrusions, extrusions) were assessed with a CT scan and then followed with MRIs. What they found was that by 6 months to 1 year, herniated disc material had dissolved in many of the cases. The larger the herniation (extrusions), the faster the material was reabsorbed. Long term studies have shown that though surgical intervention might have a faster initial recovery time, conservative outcomes are as effective at 5 and 10 years. 

Why do I feel pain in my leg if the problem is in my back? 

The nerves that go to the legs come off of the spinal cord. As they come off, they run in the spinal canal and then come out between two of the vertebral bodies. When they are in the canal, they are named by the associated disc level (Lumbar 5 or L5). When the nerves come out the individual levels, they group together to make up named nerves, e.g., the sciatic nerve. It is in the canal that the disc irritates the nerve, sending pain down the leg corresponding to the disc involved and the side of the nerve that it irritates.  

If I don’t have surgery, what are my options? 

There are a lot of options for non-surgical treatment of low back pain. The first is physical therapy. Good physical therapy will allow for the disc to heal and to provide improvements in biomechanics and strength. Recent studies have shown that directed physical therapy is more successful than more random approaches. Often, this is enough.   

When the pain is too much to try physical therapy, however, epidural injections can also be very helpful. Epidural injections are safe when compared to more invasive procedures. Complications include bleeding, headaches, infections, and very rarely, injury to a nerve. However, pain reduction can be markedly improved. Studies have shown excellent pain reduction and return to function with the use of epidural injections.

The combination of these two techniques can be the most effective treatment of all -- the epidural provides pain reduction and makes the physical therapy that much more successful.