At a glance

  • A slipped disc can cause severe pain if it pushes against nerves.
  • The pain can travel down the leg and into the foot. The leg might also tingle or feel numb.
  • The symptoms usually go away on their own after a few weeks.
  • Until then, it's a good idea to treat the pain so you can stay as active as possible.
  • Surgery is only very rarely needed.

Introduction

Photo of a patient and doctor with x-ray image (Zsolt Nyulaszi / iStock / Thinkstock)

Many people have back pain that keeps on returning. Usually it is hard to say what the exact cause is. But if you have pain that radiates down your leg and into your foot, it may be a sign of a slipped spinal disc, or “herniated disc.”

The spinal discs are found between the vertebrae bones in the spine. They have an elastic casing made of cartilage and a gel-like center (nucleus pulposus). A slipped disc occurs if the spinal disc tissue pushes out, or "herniates," between the vertebrae. This herniated tissue may put pressure on the spinal nerves and irritate them.

A slipped disc can be very unpleasant. But the good news is that the symptoms usually go away on their own within less than six weeks in most people with this problem. And not every slipped disc is painful.

Symptoms

A slipped disc can cause very sudden and severe shooting pain. If it occurs in the neck area, the pain might radiate into the arms. Slipped discs in the lumbar (lower back) region are the main cause of sciatica. Sciatica is pain that radiates down one leg and into the foot. As well as the typical radiating pain, a slipped disc can also lead to pain in the low back region.

In rare cases, numbness in the buttocks or signs of paralysis may develop in addition to the pain. These symptoms are signs of a more serious problem, like nerve damage. If it affects the function of the bladder or bowel, immediate treatment is needed. That is called "cauda equina syndrome" (CES), and is a medical emergency.

But a slipped disc doesn't always lead to noticeable symptoms. This can be seen in studies in which adults who didn't have back pain were examined using magnetic resonance imaging (MRI): More than 50 out of 100 of them had a bulging (herniated) spinal disc. About 20 out of 100 had a spinal disc that was already quite damaged or even had tissue coming out of it, without causing any symptoms.

Causes

In most people, slipped discs are the result of wear and tear. Over the years, the spinal discs lose their elasticity: Fluid leaks out of them and they become brittle and cracked. These changes are a normal part of the aging process – which varies from person to person, though. Very rarely, an accident or severe injury might also cause damage to a spinal disc and leave it herniated.

Spinal discs act as shock absorbers between the vertebrae in our spine. If a spinal disc is no longer able to bear the strain, it can result in a slipped disc. The associated pain probably arises when part of the spinal disc pushes against a nerve in the spinal cord.

Illustration: Healthy and slipped disc (cross-sectional view of the lumbar spine – from above)Healthy and slipped disc (cross-sectional view of the lumbar spine – from above)

 

When herniated disc tissue irritates a nerve root in the region of the lumbar spine (lower back), it often causes typical sciatic pain. The nerves that run through the spinal canal connect to the sciatic nerve at the pelvis. The sciatic nerve then runs down the legs. As well as being painful, an irritated sciatic nerve can also cause pins and needles and numbness.

 

Illustration: Position of the spinal and sciatic nervesPosition of the spinal and sciatic nerves

 

Doctors categorize slipped discs by severity:

  • Prolapse: The disc bulges out between the vertebrae, but its outermost layer is still intact.
  • Extrusion: There is a tear in the outermost layer of the spinal disc, causing spinal disc tissue to spill out. But the tissue that has come out is still connected to the disc.
  • Sequestration: Spinal disc tissue has entered the spinal canal and is no longer directly attached to the disc.

These categories reveal little about what symptoms occur or how severe they might be. But knowing what type of slipped disc someone has is important for the choice of treatment and understanding how the condition might go on to develop.

Prevalence

It is estimated that 1 to 5% of all people will have back pain caused by a slipped disc at some point in their lives. Slipped discs are more common in people over the age of 30, and are about twice as common in men as they are in women.

Outlook

Pain and restricted movement caused by a slipped disc subside on their own within six weeks in about 90 out of 100 people with this problem. It is believed that, over time, the body gets rid of part of the prolapsed tissue or that it shifts position so that the nerves aren't irritated anymore.

A painful slipped disc can go on to develop in very different ways: The pain can start very suddenly, and then disappear again very quickly. Some people have permanent pain that lasts a long time, while others have it again and again.

If the symptoms last longer than six weeks, it is unlikely that they will go away on their own.

Diagnosis

Doctors are usually able to determine what is causing acute back pain by asking a few questions and performing a physical examination. X-rays aren't very suitable for diagnosing a slipped disc because they don't say much about the situation: A lot of people who are found to have spinal disc damage on x-ray images don't have any symptoms. Other imaging techniques such as magnetic resonance imaging (MRI) are only rarely needed, if any of the following occur:

  • Numbness or paralysis in one or both legs
  • Impaired function of the bladder or bowel
  • Unbearable pain despite treatment
  • Severe symptoms remain for many weeks despite treatment
  • Another condition is thought to be causing the pain, for example a tumor

So there are often good reasons why doctors don't suggest doing any complex diagnostic examinations at first if you have back pain: Imaging techniques may show a supposed cause of back pain that actually has nothing to do with the symptoms. This kind of misdiagnosis can then result in unnecessary treatment that may itself be harmful.

Treatment

Even severe sciatic pain can go away on its own after a while. Until it does, various kinds of pain relief treatment can help to cope with the symptoms. The aim is to stay as active as possible. But treating the pain doesn't speed up your recovery. Most of the work is usually done by the body itself.

If severe sciatic pain caused by a slipped disc lasts longer than six weeks, surgery may be an option to try to relieve the pressure on the affected nerve. Surgery is also always done if the nerves are so severely affected that the bladder or the bowel is no longer functioning properly or certain muscles have become very weak. But that is rare.

Learn more

Rehabilitation

The goal of rehabilitation is to improve the symptoms and restrictions resulting from a slipped disc, and strengthen the muscles in the torso in order to improve the stability of the spine.

Rehabilitation may include patient education, stretching and relaxation exercises, strength training and other measures. It is an option for people who have been greatly affected by their back pain and are unable to work or perform other everyday activities. Follow-up rehabilitation may help after surgery too.

Further information

When people are ill or need medical advice, they usually go to see their family doctor first. Read about how to find the right doctor, how to prepare for the appointment and what to remember.