What it is and what to expect

There are two different types of neurophysiology tests – nerve conduction studies (including electromyography) and electroencephalograms (EEGs).

More information about each of these can be found below.

Nerve conduction study (NCS) and electromyography (EMG)

NCS is performed to check how your nerves are conducting information in your body. The nerve may conduct slowly or may not conduct at all if the nerve is affected by an underlying pathology or if the nerve is trapped/blocked.

The nerves may also be affected if there is a long history of diabetes and tend to get slower as we age.

EMG is performed to study the muscles. Muscles contract or relax based on impulses they receive from the brain through the nerves. This study is to check the activity in the muscles.

Why your doctor asked you to do this test

You may be experiencing numbness, tingling, pain or weakness in your limbs while resting, or deterioration in strength.

It is normal to experience these symptoms during some strenuous activities, however, it needs to be verified if it is ongoing and if present at rest to rule out underlying causes. This test may help detect or rule out nerve/muscle disease.

NCS involves a mild electrical current which is somewhat similar to static electricity we experience sometimes.

The scientist performing this test will attach some sticky electrodes and record the response from your extremities. The intensity of electrical current varies depending on the nerves tested and underlying physical condition.

The electrical current used for NCS is considered very low and most patients tolerate it very well. Some patients may be more sensitive and may feel uncomfortable during the test. However, if discomfort is experienced, it does not last after the procedure.

The test takes about 15–60 minutes, depending on the number of nerves to be tested.

EMG test involves inserting a tiny needle into the muscles to study them.  You may be asked to contract or relax the muscle during the test.

NCS/EMG are helpful in diagnoses of:

  • muscle disease
  • nerve problems in the spine
  • neuromuscular junction disease
  • peripheral nerve problems due to infection, compression, immune system attacks.

EMG is also used for guidance during injections.

It is a very simple test. You do not need to fast or get sedation for this test.

  • Try to keep your extremities (hands and feet) warm before and during the test as cold temperature can give misleading results or delay the actual procedure.
  • Please wear something loose that allow access to the body to be tested or that can be easily removed.
  • Do not use any moisturiser or oils before your test. When testing hands, the scientist performing your test may remove your wrist watch or any other jewelry.

If you are having EMG done, please advise if you are on blood thinners or anticoagulants.

The electric current used during the test is low and does not cause any side effects. There are no risks associated with NCS.

Please let us know if you had any operations done recently, if any pacemaker or cardiac defribillators.

EMG test may cause mild bleeding and bruising after use of needle and low risk of pain where the needles were inserted.

We generate reports mostly immediately after the test, however, if the clinics are busy, we may generate reports towards end of the day.

In any scenario, we will send the reports to your referring doctor/GP.  The doctor reviewing your test will let you know about the findings and you can discuss results further with your referring doctor.

Electroencephalogram (EEG)

Your brain cells communicate with each other through electrical activity and they do so all the time including when you are asleep.  This electrical activity may show changes when there is disturbance in the normal routine of communication.  EEG records this electrical activity which helps the specialist understand what is going on in the brain and may aid in diagnosis.

Why your doctor asked you to do this test

EEG detects changes to normal pattern of electrical activity in the brain helping the doctors address the issue you are presenting with.

It is used for detecting changes in brain caused by:

  • Brain tumours
  • Dementia
  • Encephalitis
  • Encephalopathy
  • Head injury
  • Medication/drug/alcohol-related changes
  • Memory problems
  • Migraine
  • Seizure disorder
  • Sleep disorders
  • Stroke

In the hospital, it is also used for patients during surgery or in coma to assess the brain activity.

Comprehensive EEG study is done in special a neurophysiology laboratory at the hospital.

The scientist performing EEG test will mark your scalp, scrub the surface gently and place metal disc wired electrodes with paste adhesive on the surface of the scalp.

About 20+ electrodes will be placed all over your scalp at specific locations after which you will lie down on a bed or reclining chair.  This process takes about 10–15 minutes. The scientist will give you instructions to follow throughout the test while recording EEG.

The whole process involves absolutely no pain.

After the test is complete, the scientist will remove the electrodes from your scalp.

In some instances, you may undergo EEG for over one hour and up to 24 hours. All the EEG recordings are done with a video recording to correlate body movements and artefacts with EEG changes.

Before the test you will need to:

  • shampoo your hair on the day of EEG appointment. Please do not use any hair conditioners, gels, sprays or oils as they may interfere with electrode placement and recording
  • provide list of medications you are currently taking to the scientist performing this test
  • avoid drinking alcohol the day before the test
  • avoid eating or drinking caffeine-containing beverages at least eight hours before the test
  • avoid eating or drinking beverages containing high sugar content at least eight hours before the test.

Please wear comfortable clothes for the test. Your hair may need to be let loose during the test. Use less hair bands sparingly so easily untied.

We do not give any medications/sedatives prior to the test and you can perform your daily activities immediately after the test, except when you are sleep-deprived.

Sleep-deprived EEG

You may be asked to undergo sleep-deprived EEG which means you do not sleep past 4am in the morning.

Please organise someone to drive you to and from the venue and avoid driving while you are sleep-deprived. Take rest after your test before you engage in any activities. Sleep-deprived EEG recording commences at 8am in the morning. Please try to be at the venue by 7:30 am.

Please bring MRI or CT scans and any prior EEG reports to correlate with the results of the current EEG test.

There are no risks associated with EEG.The test is absolutely pain-free.

Sometimes EEG may be performed ceasing your medication to assess related changes and in these instances, your specialist will inform you what to expect and all the necessary precautions will be taken to keep you safe.

If seizures occur during the test, medical aid is available at the premises.

EEG recording is reviewed by the neurologist and is usually reported within 48 hours of the test. The report is sent to your referring doctor/GP.

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