A herniated disc refers to a medical condition in which damage to the outer, fibrous rings of an intervertebral disc allows the softer central portion to bulge out beyond the damaged rings. This condition is sometimes colloquially known as a slipped disc.
There are two possible causes of this condition – degeneration of the spinal discs (major cause) or trauma (minor cause).
Symptoms can range from little or no pain to severe neck and lower back pain, numbness, tingling and (in some cases) motor problems like weakness, paralysis or reduced reflexes.
Treatment of disc herniation usually involves taking pain relief medication and avoiding movements that might cause pain. Physical therapy is also useful in some cases. In the rare case that these measures do not substantially relieve pain, surgery may be considered.
The spine includes discs that sit between each pair of adjacent vertebrae and act as shock absorbers between the vertebrae. The discs have soft interiors with the consistency of jelly (called nuclei), but are encased in rubbery tough shells called annuli.
A disc becomes herniated when (due possibly to wear and tear) a tear appears in the annulus or shell and some of the inner material starts to push through the opening caused by the tear. This happens most frequently at S1, L5 and then L4 levels, in that order.
Causes Of Disc Herniation
In most cases, the disc herniation process described above is the result of degeneration of the shell of the disc as a result of age-related wear and tear. Discs tend to lose their suppleness and flexibility as aging occurs. This makes them more susceptible to tears or ruptures every time you twist your back or subject it to stress.
People who regularly lift heavy objects, but do so by bending their backs excessively, can cause disc herniation.
In some other (but much rarer) cases, disc herniation can be the result of a fall or blow to the back.
In some other cases, there is no discernible or discrete event that the patient can identify as having caused the herniated disc(s). Some people seem to have an inherent weakness in the outer part of the affected disc. This renders them more susceptible to disc herniation than people who don’t have this weakness.
Disc Herniation Risk Factors
The following factors can increase the risk of suffering disc herniation:
Excess body weight. This places extra pressure on the lower back and on the intervertebral discs in that area;
Occupation. Having a job that requires prolonged sitting (especially driving) or plenty of heavy lifting (for example weightlifting) can increase the risk of developing the condition, especially if the technique used for lifting places too much stress on the lower back;
In some cases, patients are simply born with a predisposition to disc herniation;
Smoking – some research points to smoking reducing the supply of oxygen to the dicis, leading the shell to deteriorate more quickly and be subject to damage.
Symptoms Of A Herniated Disc
As with spinal stenosis, herniated disks can appear either at the back of the neck (cervical spine area) or (more commonly) in the lower back (lumbar spine area).
Symptoms will depend on whether the damaged disc is pressing on the nerve roots in or emerging from the spinal column. If so, symptoms will also depend to a degree on the part of the spine where the herniated disc and affected nerves are located.
One notable characteristic of the symptoms of a herniated disc problem is that they tend to appear on one side of the body only. Although the problem is in the back near to the spine, pain can occur in the back as well as anywhere along the course of the affected nerve leaving the spine at the point where the disc prolapse happens. Thus, pain can be felt in the buttock, thigh and can radiate below the knee down to the foot. Symptoms may be caused by compression of the nerve and/or irritation due to inflammation caused by the prolapse.
It should also be noted that (again like spinal stenosis) a herniated disc can sometimes (have) cause no noticeable symptoms even though it is apparent on an imaging study.
However, when symptoms do appear, they can be as follows:
If one or more of the lumbar discs is herniated, symptoms can include sharp or burning pain in the buttock, thigh, calf and foot;
If one or more cervical disks is herniated there will more likely be sharp or burning pain felt in the shoulder and/or arm;
Numbness, tingling (pins and needles) or muscle weakness will be felt in either the upper or lower body, depending on whether the nerves affected by the disc herniation are in the neck or lower back.
There may by midline tenderness in the back at the level of the disc herniation
A rare complication of a disc prolapse is cauda equina syndrome (CES), due to compression of the nerves at the bottom of the spine.. This typically leads to (Severe cases of disc herniation can also produce) bladder or bowel dysfunction (retention or incontinence), (Another possible complication is) “saddle anaesthesia” – a gradual loss of sensation in the inner thighs, the backs of the legs and the area surrounding the rectum as well as weakness of one or both legs. CES is a medical emergency which requires immediate neurosurgical intervention.
Diagnosis of a possible herniated disc condition will usually be based on:
A physical examination in which the doctor will check the patient’s back to ascertain the location of any back pain and/or tenderness. As part of the examination, the patient might be asked to move his/her legs into various positions while lying flat;
A neurological examination that will include testing the patient’s reflexes, strength, ability to walk and sensory perception.
In most cases, the above tests are enough for the doctor to make a definitive diagnosis. However, if the doctor is still not certain, imaging tests such as a magnetic resonance imaging (MRI) scan will be requested. X ray tests are usually not able to detect the presence of herniated discs but they can help the doctor rule out other potential causes of the patient’s pain. The doctor is likely to order imaging tests to exclude alternative causes of the symptoms like a tumour or a metabolic problem.
There are also tests that the doctor can conduct to determine how well the patient’s nerves are transmitting signals to the central nervous system. Two such tests are nerve conduction and electromyography studies.
Herniated Disc Treatment
Treatment of a herniated disc condition can be classified into 3 categories:
A doctor may, as a first option, prescribe pain medication (Tylenol or Advil, for example). Other NSAIDs like naproxen or diclofenac may be used as well, but can only be obtained on prescription. Weak opioid medicines like codeine can be added if the above are ineffective or cannot be taken. If these are not effective, cortisone injections may be recommended into the area close to the spine (but not the spine itself).
Muscle relaxants may also be prescribed to deal with muscle spasms.
Sometimes, a medicine like amitriptyline can be prescribed, especially if the pain is thought to be neuropathic in nature.
For relief of intense pain, doctors may suggest opioids. However, these (bring) are associated with a risk of addiction and patients should exercise extreme caution in using them.
Doctors can refer the patient to a physical therapist who can design an exercise program to minimize the back and leg pain the patient may be experiencing. A chiropracter or osteopath can sometimes give advice about manipulation and/or other physical treatments. The goal will be to help the patient perform regular daily activities with less pain. The patient should be advised to carry on with his/her normal daily activities as much as possible and to avoid complete bed rest.
In rare cases, the patient may be asked to consider surgery to correct the problem. This may involve removing the protruding portion of the herniated disc. In extremely rare cases, the disc may be removed entirely and the adjacent vertebrae fused together.
Another rare surgical treatment option is the replacement of a herniated disc with an artificial one.
Surgery is usually considered if the symptoms are very severe and have not settled after at least 6 weeks or so. Not more than about 1 in 10 patients end up having surgery for their prolapsed disc.