Lumbar Disc Protrusion (Slipped disc in the lower back)

 

Condition   

 Herniation of part of the disc causing pressure on a nerve or the cauda equina.  The terms ‘herniated disc’, ‘disc protrusion’ and ‘slipped disc’ mean essentially the same. The term ‘disc bulge’ is often used to describe some mild bulging of the disc into the lumbar canal. This is often seen in degeneration of the spine. Whether the disc is bulging or is herniated makes no difference to the treatment. This will depend on the patients symptoms. Most disc protrusions occur in the lower lumbar spine. If it occurs in the upper lumbar spine symptoms may be confused with other conditions or misinterpreted. The cause is usually degenerative (wear and tear) but can also follow trauma.

Symptoms 

Most patients experience initially low back pain due to the rupture of the ring of disc (annulus fibrosus). It is then followed by pain shooting down the leg (‘sciatica), usually below the knee (lower lumbar disc protrusions). In disc protrusions of the upper lumbar spine the pain may only radiate to the thigh or into the knee. This can be associated with pins and needles and in some cases weakness of the leg or foot. In rare cases a disc protrusion can cause problems with the control of passing urine which requires immediate medical attention (cauda equina syndrome).

Complications

Permanent numbness or weakness in the leg/foot, cauda equina syndrome or neuropathic pain due to nerve damage. 

Investigations

Patients with a suspected disc protrusion should have an MRI scan unless the symptoms resolve quickly. There is no indication for plain x-rays or blood tests unless other causes are suspected (red flags). If a patient cannot have an MRI scan (e.g. cardiac pacemaker) a CT scan or myelogram is indicated.

Treatment

Non-operative

Most (~85%) of all patients with a disc protrusion respond to conservative management within ~3 months. This usually composes of regular analgesia and physiotherapy. Other manual therapies by osteopaths and chiropractors can also play a role. If the pain does not settle surgery should be considered. Disc protrusions cannot be ‘pushed back into place’ as some manual therapists may claim. The reason many patients improve with time is shrinkage of the protruded disc and settling of the inflammation of the nerve and surrounding structures.
Epidural injections for sciatica can be very effective in the acute phase as they improve the pain and settle some of the inflammation. However, an injection is just another form of painkiller and does not alter the natural course of the problem. Injections certainly do not provide a long term solution and should only be repeated in few selected cases.

Operation

Lumbar microdiscectomy is the surgical treatment of choice for patients who have not responded to conservative treatment or suffer nerve damage (weakness or progressive numbness). In some cases a laminectomy is required if the disc protrusion is very large or in a cauda equina syndrome.
There is no evidence that laser surgery or injection of chemicals into the disc (chemonucleolysis) is better than conventional microdiscectomy.
 

Lumbar disc prutrusion

Lumbar disc prutrusion

cross section of disc protrusion

cross section of disc protrusion