Will an MRI Show Nerve Damage?

MRI is very good at showing structures. It can show a disc pressing on a nerve root in the spine, narrowing around the spinal cord, or changes in the brain. What it does not do is measure how well a nerve is carrying signals. For that, specialists use nerve conduction studies and electromyography.

So whether an MRI will show your nerve problem depends on the question being asked. This guide explains where MRI helps, where other tests are used first, and the symptoms that need urgent attention rather than a scan.

Where MRI is useful

The clearest example is sciatica. The NHS describes sciatica as what happens when the sciatic nerve, which runs from the lower back to the feet, is irritated or compressed. MRI of the lower back can show what is pressing on the nerve root, most often a disc. The same applies in the neck, where MRI can show a disc or bony change pressing on a nerve running to the arm.

Even so, a scan is not always the first step. NICE's guideline on low back pain and sciatica advises against routine imaging in a non-specialist setting and suggests considering imaging in a specialist setting only if the result is likely to change how you are managed. Many people with sciatica improve over weeks to months without a scan. Our guide to which scan for back pain and sciatica goes into this in more detail.

Peripheral neuropathy: other tests come first

Peripheral neuropathy is damage to the nerves outside the brain and spinal cord, often causing numbness, tingling or pain in the hands and feet. The NHS explains that diagnosis usually starts with your GP asking about symptoms, examining you and arranging blood tests, for example to check for diabetes or vitamin B12 deficiency.

To confirm a neuropathy, a neurologist may arrange a nerve conduction test, in which small electrodes on the skin stimulate the nerves and measure the speed and strength of the signal, and electromyography, which measures the electrical activity of the muscles. The NHS notes that scans such as an X-ray, CT or MRI may be used to look for an underlying cause, but they are not how the neuropathy itself is measured.

Trapped nerves in the wrist and elsewhere

Carpal tunnel syndrome is a good illustration. The NHS says it can usually be diagnosed from your symptoms and an examination of your hand. If the health professional is not sure, they may refer you for a nerve conduction test of the wrist, or for scans such as an ultrasound or MRI. In other words, the scan supports the diagnosis rather than replacing the examination.

Symptoms that need urgent help, not a booked scan

The NHS advises going to A&E or calling 999 if you have sciatica and any of the following. These can be signs of a serious problem that needs treatment in hospital as soon as possible.

• Sciatica on both sides.
• Weakness or numbness in both legs that is severe or getting worse.
• Numbness around or under your genitals, or around your bottom.
• Difficulty starting to pee, being unable to pee, or not being able to control when you pee, when this is not normal for you.
• Not noticing when you need to poo, or not being able to control when you poo, when this is not normal for you.

Do not wait for a private appointment if any of these apply.

Choosing the right scan privately

If a clinician has recommended an MRI for nerve symptoms, the body part matters: lumbar spine for leg symptoms, cervical spine for arm symptoms, and sometimes the wrist, elbow or another specific area. Many MRI clinics accept self-referral after their own safety screening, but each clinic sets its own policy, and our guide to private MRI without a GP referral explains the options.

Clinics listed on FindScan publish the price they charge for each scan and we show it as the clinic sets it. You can search MRI scans by location, and our guide to MRI for lower back pain covers what that scan can and cannot tell you.