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(Also called Herniated or Prolapsed Disc)
The spine consists of a series of vertebra that are stacked on top of another from the neck to the pelvis. These vertebraes are connected and kept in correct position by the disc that is between the vertebra and also the facet joints that are located on the side of the vertebral bodies and these interlock with each other.
There are also supporting ligaments and tendons. The discs between the two adjacent vertebraes are composed of a central, soft, jelly-like substance called the nucleus pulposus and an outer, tougher fibrous part called the annulus fibrosus.
What happens in some people is that the tough annulus fibrosus becomes damaged and tears, leaving a defect in the strong outer layer. A bit of the nucleus pulposus can then push through this tear and end up in the spinal canal and press against the nerves in the spinal canal (see figure 4.1). This can be because of a traumatic injury but is usually due to an inborn predisposition towards weak discs.
What is it?
In this condition there is herniation of the nucleus pulposus through the annulus fibrosus. The spinal cord extends from the brainstem to the lower spine and stops just below the level of the thoracic and lumbar spine junction. A slipped lumbar disc purely compresses nerve roots that are dangling in the spinal canal. This is because there is no spinal cord at this level but only nerve roots that originate in the spinal cord. A herniated cervical or thoracic disc, on the other hand, can compresses the cord or the nerve roots as they leave the spinal cord.
Figure 1.4 The four stages of disc damage, leading to herniation of disc material.
A: Annular tear. At this stage the disc is intact and there is a small tear only in the tough outer layer (annulus fibrosus).
B: Disc prolapse. The soft centre of the disc (nucleus pulposus) is now starting to squeeze out of it’s normal position but is still contained within the outer layer.
C: Disc extrusion. At this point the soft nucleus has broken through the annulus.
D: Disc sequestration. At this point the nucleus has broken through the annulus and a piece of the nucleus has broken off from the rest and is lying loose in the spinal canal.
What are the symptoms?
When the part of the nucleus that herniates compresses the nerves in the spinal canal, you may experience back pain and pain in one or both legs. Some people have a feeling of pins and needles in the legs and feet. Pain and discomfort may also be felt in the hip, between the shoulder blades and in the groin. The later effects are weakness and unsteadiness of the legs and feet.
How is it diagnosed?
A clinical examination by your doctor or therapist will allow for a reasonable suspicion but the only definite way is by doing a magnetic resonance (MR) scan (see the section on tests). Sometimes because of technical factors a CT scan is performed (see the section about tests). This is usually when a MR scan cannot be performed due to the unavailability of a MR scanner, when there are contra indications to doing a scan or there are technical factors like the presence of metal fusion apparatus in the spine that make a MR scan unreliable.
See the section on tests for the terminology that you will find on your MR scan report and what it means in plain English. Other tests that might be used are discograms and nerve blocks. Sometimes EMG’s are also used (see the section on tests).
What is the treatment?
There are always four options:
No treatment - This is acceptable if there is no serious nerve compression - therefore in the absence of spasticity or muscle weakness. There are always people who choose this option for a variety of personal reasons. There is a large proportion of patients in which the symptoms will get better with time without an operation.
Non-invasive treatment - The initial treatment for a cervical disc herniation is conservative treatment that might include anti inflammatory medication, analgesics, physiotherapy and other manual treatment such as chiropractic manipulation, pressure point therapy, massage therapy, traction and other therapies.
Semi-invasive - These include procedures like radiofrequency rhizotomies (see the section on rhizotomies), caudal or sacral blocks, epidural blocks and disc nucleoplasties (see the chapter on nucleoplasties). These treatments are highly effective, have very few side effects or complications and are performed as day procedures. These procedures have a very definite place in the non - surgical management of cervical disc disease.
In performing the rhizotomy, thin needles are inserted through the skin of the back. These needles are placed on the small nerves that supply the joints between the two vertebral bodies and a radiofrequency generator is the attached and the nerve is inactivated by radiofrequency pulses.
The nerves that are treated are not important nerves and it is not dangerous to shock them with radiofrequency pulses. When inactivated, these nerves cannot conduct pain sensations from the joint to the brain. This means that the pain sensation from the facet joints decrease or clear completely up. This is however a temporary effect and the treatment as to be repeated when the pain returns.
In performing caudal blocks, a needle is placed at the base of the spine and a mix of steroids and local anaesthetic is injected into the spinal canal. This is to try and combat inflammation of the nerve roots.
An epidural block is similar to a caudal block, but in this case the needle is placed under the lamina of the vertebra or in the foramen where the nerve leaves the spinal canal (see the section on anatomy). A similar mixture is injected with the aim to reduce inflammation and pain.
In performing a nucleoplasty, a thin needle is inserted from the back through the skin into the disc and a similar kind of radiofrequency pulse is connected. In this case the disc is shrunk in a molecular process where some of the disc material is changed into a gas which escapes from the back of the needle.
Currently only some spinal surgeons are trained in these techniques and you should enquire about these directly to see whether you qualify for these treatments and whether they are suitable for your condition.
If conservative management is unsuccessful, then surgery is usually indicated. In situations where there is muscle loss or sensation loss due to a compressed, nerve, surgery is considered much earlier. Compression that continues for too long can cause permanent nerve damage. The longer the duration of the symptoms, the less is the chance of success when operating to decompress nerves.
Invasive (surgery) - the indications for surgery are:
1.) Failed conservative management (six weeks at least)
2.) Pain that does not respond to any other treatment modality and is sufficently severe to limit your daily activities and quality of life. This includes local lower back pain, referred pain and radicular pain.
3.) Muscle weakness due to nerve compression (radicular weakness)
4.) Spasticity
5.) Cauda Equina syndrome or Conus Medullaris syndrome. These are serious conditions that are characterised by weakness, sensory loss and bowel and bladder dysfunction. These are emergencies that require immediate surgery.
There is a whole spectrum of operations that might be suitable and please see the relevant section on procedures for the procedure that your surgeon is suggesting.
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