What is it?
A prolapsed disc, sometimes referred to as a slipped or herniated disc, is when the inner, softer part of the disc (the nucleus pulposus) bulges out (herniates) through a weakness in the outer part of the disc, which then may press on nearby structures, such as a nerve coming from the spinal cord.
Some inflammation also develops around the prolapsed part of the disc. Inflammation may irritate a nerve and also causes swelling, which may put pressure on a nerve.
Why does it occur?
Why some people develop prolapsed discs, while others with similar physical attributes and lifestyles do not, is unclear. Some people may simply have a weakness in the outer part of the disc or discs that are affected. There are a number of things that may put extra pressure on and cause the inner, softer part of the disc to squeeze out through the weakened outer part of the disc, such as sneezing and awkward bending or heavy lifting. Other factors that may put someone with weak discs at greater risk of a prolapse are: lifestyles that involve lifting or sitting; weight-bearing sports, age; being overweight.
What are the symptoms?
Pain due to a prolapsed disc can be severe and usually comes on quite suddenly. You can alleviate the pain by lying still. Moving your back, coughing and sneezing often make it worse.
If a nerve coming from the spinal cord is trapped by a prolapsed disc, this can can cause severe or mild nerve root pain. It can also be aggravated by inflammation caused by a slipped disc. Although originating in the back, this burning-type pain can be experienced elsewhere in the body, right down to the feet.
The sciatic nerve, a large nerve made up of several smaller nerves that come out from the spinal cord in the lower back, is the most commonly affected with prolapsed discs. It travels deep inside the buttocks and and down the back of the leg, each leg having its own sciatic nerve.
The irritation or pressure on the root nerve can also cause pins and needles, numbness or weakness in part of a buttock, leg or foot. The exact site and type of symptom you experience will depend on which nerve is affected.
Cauda equina syndrome, in which the nerves at the bottom of the spinal cord are under pressure, is a particularly serious type of nerve root problem, and can be caused by a prolapsed disc. As well as back pain, it can cause bladder and bowel problems, numbness in the saddle area around the anus, weakness in one or both legs, and needs to be treated urgently.
How is it diagnosed?
Your consultant will usually be able to diagnose a prolapsed disc from your symptoms, and an examination. If your symptoms persist, an x-ray or MRI scan may be done to get an idea of the site and size of a prolapsed disc. and will be necessary if surgery becomes an option.
How is it treated?
The best course of treatment will depend on a number of factors, including your age, the level of pain you are experiencing, and what type of activity levels you wish to maintain, or return to.
This could include suggested changes in lifestyle combined with some painkilling medicines. In more severe cases we may recommend an epidural, which is an injection given into where the sciatic nerve comes out of the spine. The injection contains a type of local anaesthetic and a steroid, that acts as a is a very strong anti-inflammatory, and serves as a longer-term painkiller. These options can mitigate the symptoms and, in some cases, postpone the need for surgery.
Surgery may be considered if the symptoms are very severe and have not settled after six weeks. The vast majority of those with prolapsed discs will find will ease and are not acute enough to warrant surgery.
If surgery is thought necessary, the aim would be to cut out the prolapsed part of the disc to release pressure on the nerves, which often relieves the symptoms. Your consultant will talk to you about the pros and cons of surgery, and why it might be the best option in your case.
The One Orthopaedics team specialists
Consultant Orthopaedic Surgeon FRCS (Tr&Orth), Spine
Pain Management Consultant FRCA FFPMRCA