Your GP will usually be able to diagnose a slipped disc from your symptoms and medical history.
You'll also have a physical examination, where your GP may test your:
- muscle strength
- walking ability
- sensation in your arms and legs
While you're lying flat or sitting, your GP will slowly raise your legs one at a time to see if it causes any pain or discomfort in your legs.
The test stretches the nerves in your spine. If a disc is pressing on a nerve, this stretching can cause pain, numbness or tingling.
Pressure on a nerve
Your GP may test whether there's any pressure on a nerve in your neck by asking you to bend your head forward and to the sides while applying some pressure to the top of your head.
If this causes any pain or numbness to increase, it's likely that a slipped disc is putting pressure on a nerve in your neck.
In most cases, further tests aren't needed because the symptoms of a slipped disc usually settle down within one to three months.
But if your symptoms don't ease after three months, further tests may be recommended to help pinpoint the exact location of the slipped disc and assess how well the nerves are functioning.
Some of the tests you may have are described below.
Nerve conduction test
In cases where there's uncertainty, a nerve conduction test may be used to help diagnose a slipped disc. It can also be used to measure how well the electrical signals are being transmitted through your nerves.
During the test, small metal discs called electrodes are placed on your skin. They release small electric shocks that stimulate your nerves, allowing the speed and strength of the nerve signal to be measured.
Magnetic resonance imaging (MRI) scan
A magnetic resonance imaging (MRI) scan uses a strong magnetic field and radio waves to produce detailed images of the inside of your body.
MRI scans are effective at showing the position and size of a slipped disc. They can also pinpoint the affected nerves.
Computerised tomography (CT) scan
A computerised tomography (CT) scan uses a series of X-rays to scan parts of your body. A computer is used to build up detailed images of your body.
This produces cross-sectional images of your spinal column and the structures surrounding it. Like an MRI scan, a CT scan can pinpoint a slipped disc, although it's often not as effective.
Normal X-rays aren't usually used to investigate slipped discs because they only detect bone and don't give a view of the nerves and spinal cord.