What they are

A nerve conduction study (NCS) and electromyography (EMG) are two related tests, usually performed together in the same appointment, that assess how well your nerves and muscles are working. A nerve conduction study measures how quickly and strongly your nerves carry electrical signals; EMG examines the electrical activity of your muscles, both at rest and when you gently contract them. Together they give a detailed picture of the health of the peripheral nerves and the muscles they supply — information a scan or blood test cannot provide.

What the appointment is like

The tests are carried out in the clinic and usually take around 15 to 60 minutes, depending on how many nerves are assessed. For the nerve conduction study, small surface electrodes are placed on the skin and brief, low-level electrical pulses are used to stimulate the nerve; most people describe the sensation as a quick tingle or tap, generally painless, though a little mild discomfort is normal. For the EMG, a very fine needle electrode is placed into one or more selected muscles to record their electrical activity, and you may feel a small amount of discomfort as the needle is positioned. No sedation is needed, and you can drive yourself home and return to your normal activities afterwards.

How it helps with diagnosis

Nerve conduction studies and EMG help us pinpoint where a problem lies and how significant it is. They can confirm and localise a trapped or compressed nerve — such as in carpal tunnel or cubital tunnel syndrome — identify generalised nerve conditions, assess pressure on a nerve root in the spine, and distinguish a problem arising from the nerves from one arising in the muscles themselves. The results also guide treatment: whether a problem is likely to settle with conservative care, whether an injection or procedure may help, or whether referral for surgical assessment is warranted. Findings are always interpreted alongside your symptoms and examination.

How to prepare for your test

A little preparation helps the test run smoothly and keeps the readings as accurate as possible. Before your appointment, please keep the following in mind:

• Skin care. Do not apply any moisturisers, lotions, or body creams on the day of the test, as these can interfere with the electrical signals.
• Jewellery. Please remove any jewellery or metal accessories, as these need to be taken off before the test begins.
• Clothing. Wear loose, comfortable clothing that allows easy access to your arms and legs.
• Temperature. Try to keep warm before your appointment — cold hands and feet can affect the accuracy of the nerve readings.
• Medication and food. You do not need to fast, and you can take all of your usual regular medications.
• Medical devices. If you have a pacemaker or other internal cardiac device, please let the clinic know before your appointment.
• Driving. You can return to driving immediately after the test.

Your results

Once your study is complete, the findings are interpreted in the context of your symptoms and examination. Here is what happens next:

• Your results are analysed by your specialist.
• The results may show where along the nerve pathway the problem lies, and whether it relates mainly to the nerve fibre itself (the axon) or to the coating around the nerve (the myelin).
• Occasionally a nerve conduction study does not identify the problem, and further tests may be needed.
• A formal report is sent directly to your referring doctor, usually within about a week.
• A follow-up appointment with your doctor may be needed to discuss what the results mean for your treatment plan.