CMT Diagnosis


If you and your GP think you may have CMT, you will be referred to a doctor who specialises in problems of the nerves, known as a neurologist.

Steps to a diagnosis

The neurologist will follow a number of steps to confirm whether you have the condition or not. The order of these steps may vary and some people will receive a diagnosis without needing to go through the whole process. Technology is changing rapidly, so the steps below should be seen as a guide rather than a blueprint.

Your doctor will take a standard patient history, including a family history. He or she will ask about your symptoms – what they are like and how long you have had them – and whether any of your family have CMT or have had similar symptoms.
Next, you will be given a neurological examination. Your doctor will look for evidence of muscle weakness in the arms, legs, hands and feet; as well as signs of muscle wasting, reduced reflexes and any sensory loss. Your doctor will also look for any signs of foot problems – such as high arches, hammer toes, inverted heel or flat feet. Any sign of enlarged nerves will also be noted: these may be seen or felt through the skin.

If there is an established family history of CMT where a family member has already received a confirmed genetic diagnosis, then clinical assessment alone may be all that is needed to make a diagnosis. Sometimes you will be offered a genetic test for the most common form of CMT (type 1A). This might be the case where there is clear family history with typical signs of CMT, or where there are a long waiting lists for electro-diagnostic tests.

The next stage may be electro-diagnostic tests. These consist of two parts:

  • Nerve conduction tests. Electrodes are placed on your skin over your peripheral motor or sensory nerves, usually on the legs. These electrodes will give you a mild electrical shock, which may be uncomfortable – or occasionally painful. The shock stimulates your sensory and motor nerves and the doctor will be able to measure the speed at which the signal was transmitted and the size of the signal.
  • Electromyography (EMG). A needle electrode is inserted through your skin to measure the electrical activity of the muscles in the legs.

Electrodiagnostic tests help doctors to distinguish between different types of CMT. If there is a test result for another member of your family with CMT, it may not be necessary for you to have an electrodiagnostic test.

In the UK, the next stage of diagnosis will be a genetic test to try to confirm which type of CMT you have. Not all the genes to do with CMT have been identified yet, or are commonly available to test, so this test may not be conclusive.

In very rare circumstances, when there is doubt about the precise diagnosis, nerve biopsy may be advised. This involves removing a small piece of peripheral nerve through a cut in the skin, usually from the calf, under local anaesthetic. The nerve is then examined in a laboratory for any signs of abnormalities.

What should happen now?

Once you have been diagnosed, certain things should happen.

You may find it useful to print out this list and talk it through with your neurologist and GP to make sure that you get the care you deserve.

  • You should receive a copy of your clinic letter. Ideally this will be phrased in such a way that you can show it to other family members. This will help them understand your diagnosis and why it would be a good idea for them to see a specialist too.
  • Appropriate follow-up arrangements should be offered to you..
  • Get a referral to see a physiotherapist with a good understanding of neuromuscular conditions and also to see an orthotist (a specialist in the use of mobility devices) if necessary.
  • Find out what to do if you discover other, new symptoms and how to check whether or not these symptoms are connected to CMT.

CMT can be well managed and well treated. But you may need to knock some heads together to get the care you deserve. If you are struggling to get the treatment you need, contact CMT United Kingdom.

This information on this page is provided by CMT UK,  for more detailed information or support please visit the CMT United Kingdom Website ‘Together we are stronger’.