Nerve Conduction Studies

The test helps detect significant abnormality or more easily assess definite clinical abnormality. With an accurate diagnosis, an appropriate treatment plan can be defined.

The procedure is very safe and is non-invasive

Why Nerve Conduction Testing is Being Performed?

In some medical conditions, the electrical activity of the muscles or nerves is not normal. Finding and describing these electrical properties in the muscle or nerve may help your doctor diagnose your condition.

If an imaging test such as an MRI does not adequately explain all your symptoms, you may require a Nerve Conduction Study. It is an extension of the physical examination and investigation. It adds information to a clinical assessment often by proving or refuting a suspicion.

An NCS can be requested because the patient is experiencing symptoms that suggest some problem with the nerves (numbness, tingling, weakness or pain) or muscles (weakness or pain)

You may also have Nerve Conduction Study (NCS) if the doctor thinks more than one health problem could be causing your symptoms.

In such cases, the test can help clarify the problem. However, usually, unless the nerve problem is a common entrapment (site of compression), other tests may be required to ascertain the exact nature of the problem.

A test is not always required in every nerve or muscle condition. A normal test can, in some instances, be reassuring. Not all nerve or muscle conditions can be excluded with a ‘normal’ test. Additionally, there is an element of operator experience in all these tests.

What Can a Nerve Conduction Study Help Diagnose?

Nerve conduction studies can help evaluate nerve problems such as polyneuropathies (damage to several nerves).

A Nerve Conduction Study can measure how your nerves are working. Doctors use nerve conduction studies to help diagnose the causes of:

• Arm or leg pain
• Numbness or tingling
• Weakness or cramping

There are several types of nerves, but generally speaking, the two major types are

• Motor Nerves - carry signals from the brain to the muscle to enable contraction and movement. Motor nerves are detected over the muscle activated by that nerve.
• Sensory Nerves - that relay information to the brain

Nerve disorders can be Local - such as trapped nerve (carpal tunnel at the wrist, the ulnar nerve at the elbow, the peroneal nerve at the knee, a pinched nerve in your neck, spine or lower back (radiculopathy).

• Nerve roots most commonly in the neck and lower back
• Plexus (major nerve trunks) in the arm or leg
• Muscle disorders
• Neuromuscular junction (the communication between the nerve and the muscle) disorders such as myasthenia gravis

More generalised problems, such as part of a medical condition such as diabetes.

Types of Nerve Conduction Testing

A Nerve Conduction Study measures how fast and how well the body's electrical signals travel down your nerves.

Related tests include

• Surface Electromyography (sEMG)
• Needle Electromyography (EMG)
• Quantitative Computerised EMG analysis

Both the Nerve Conduction Study (NCS) and Electromyography (EMG) test are diagnostic tools that aid the Neurologist in reaching a definitive diagnosis about a patient’s symptoms or complaints.

How is a Nerve Conduction Test Conducted?

Nerve Conduction Studies and EMG (Electromyography) are performed in our rooms.

Your neurologist will first perform a brief history and physical exam to identify the nerves that need to be tested.

The testing part of the nerve study only takes a few minutes. The rest of the time, your doctor will tape small electrodes over different muscles to evaluate individual nerves. Tests take approximately 25 minutes to study a single arm or leg.

Nerve Conduction Studies and Electromyography are usually performed together, with testing taking 1 hour and sometimes longer for more complex tests/examinations.

Both NCS and EMG testing can be performed multiple times throughout investigation or treatment and allows for real-time evaluation of a patient peripheral nervous system.

Before Nerve Conduction Testing

You will be given instructions on how to prepare for the test.

• Take a bath or shower to remove all oil from your skin before your test,
• Do not use body lotion, creams, powders, or emollients on your hands and feet (the most common sites of your nerve tests) on the day of the test,
• On the day of the appointment, bring a list of any medications you are taking and all insurance cards so we can make copies.
• Advise the neurologist performing the test if you:
• Use a pacemaker or other similar devices
• Take aspirin, blood thinners (like Warfarin Plavix, Heparin)
• Have haemophilia.
• If you have myasthenia gravis, please call your primary care physician 24-48 hours before your appointment and ask if you should take any medications before your EMG test.

If you have a needle EMG test, you should advise your GP and the neurologist. A measurement of how thin your blood is may be important before that test can be performed.

During the Nerve Conduction Study

Firstly you will be asked to position yourself comfortably

• Your target skin area will be prepared
• Small electrodes (metallic patches that can conduct signals) are placed on your skin
• A machine is used to stimulate the nerves.:
• Records each stimulation
• Records how long the signal travels along the nerve.
• Measures the results
• Creates graphs, sounds or numbers
• Your doctor how well the nerves work.

If there is damage to the nerve supplying the muscle, the doctor can see it. The test allows the doctor to identify the nerve in your back causing the problem or the nerve in an arm or leg (such as the arm in carpal tunnel syndrome).

Some patients are understandably anxious about the intensities of the small safe electrical pulses passed via the skin but usually relax quickly when they know what to expect.

Each electrical charge feels like a small static electricity shock. Some people describe the feeling as a “strong tap.”

You must remain relaxed for the recordings to minimise the ‘noise’ (interference) in the recordings from excessive muscular activity.

After Nerve Conduction Study

After the procedure is done, patients typically return home on the same day. You should be able to drive yourself home as normal, and no sedatives are administered.

There are rarely any side effects from the NCS procedure. Although some discomfort is experienced during the test, there are often no complications. The doctor may avoid stimulating too close to the torso if you have a pacemaker or similar device.

Nerve Conduction Study Reporting

The results can reveal information about the size and speed of the electrically conducted impulse.

The size usually reveals the number of nerve fibres present and the speed, and the integrity of the myelin (insulating membrane around the nerve ‘axon’ or cable). This is why the word ‘conduction’ is used.

It should be noted that the final interpretation of the clinical meaning of the test rests with the clinician who ordered the test. This is because they can put together the whole picture.

For this reason, the neurologist performing the test can only give you limited information about the meaning of the results and may not even be able to provide any information on the next step or any possible treatments because they are unaware of all the other clinical information.

Variability of a Nerve Conduction Study

The health or disease of the nerve or muscle will affect the results of the Nerve Conduction Studies, and age can have quite a bearing on the size of some measurements, especially in the legs. The temperature of the skin and the presence of swelling in the limb are also important.