Neurophysiology

Clinical Neurophysiology is the branch of medicine concerned with recording and clinically interpreting electrical signals from the peripheral nerves, muscles, retina, brain and spinal cord.

In our Neurophysiology Department, the following tests are available:

  • Electroencephalography (EEG)
  • Sleep Deprivation Studies, using EEG
  • Electromyography (EMG)
  • Nerve Conduction Studies (NCS)
  • Visual Evoked Responses (VERs)
  • Electroencephalogram (EEG) is a diagnostic test which measure the electrical activity of the brain.  It is used to monitor brain activity under normal everyday conditions. The signals are detected by button shaped electrodes placed on the head with paste.

    What is the procedure?

    The test takes approximately 1 - 1.5 hours from start to finish.

    You will start by answering some routine questions, following which the Physiologist will explain the testing procedure to you and take measurements for the placement of electrodes on your head.

    When all the locations have been marked, the Physiologist will lightly exfoliate the skin and attach the button shaped electrodes to your head using a vaseline type paste. When all the electrodes have been placed you will be asked to lie down.

    A video recording takes place during the testing procedure for review purposes by your Consultant. Relevant data from the video will be kept with your permission, otherwise all video data is removed.

    At the end of the test the electrodes will be removed and you will need to wash your hair once home, in order to remove any remaining paste.

     

    How to prepare for a routine EEG;

    • Fasting prior to the test is not required. Please eat 2 hours before testing.
    • Abstain from caffeine on the day of testing (Coffee, tea, energy drinks etc).
    • Please arrive with clean product free hair (ie hair gel, hair spray etc) as hair products may interfere with the signals and it may take longer to achieve a readable signal.
    • Please be aware that your head will contain multiple spots of paste that will need to be washed out at home. Therefore you may wish to bring a hat with you.

     

    Paediatric EEG

    For EEG tests carried out on children, the procedure will be the same, however, extra time will be allocated for completing the test.

    Where possible, you are advised to discourage your child from napping on the day of the test or fall asleep on the journey to the hospital, as your child will be encouraged to nap during the test.

    A visit to the hospital can be stressful for a child. To help make your child more comfortable, you are welcome to bring a comforter or a non-stimulating toy which does not flash or make noises, which they can keep with them during their visit.

  • These studies use the same techniques as that of an EEG.

    The main difference between an EEG and a sleep deprived EEG, is that a patient has been kept awake for 24-36 hours prior to the test.

     

    How to prepare for a sleep deprived EEG

    • Standard protocol is to have a 24 hour period of wakefulness prior to testing.
    • You must be accompanied by another person as you are not allowed to travel/drive by yourself to and from the appointment.
    • No caffeine should be taken 24 hours prior to the test.
    • It is recommended that you are not alone during the period of sleep deprivation including the night before the test, the day of the test and the night after the test.
  • Electromyograph (EMG) is a diagnostic test used to measure the electrical activity in muscles. Motor neurons transmit electrical signals that cause muscles to contract. An EMG translates these signals into graphs, sounds or numerical values that a specialist interprets.

    Reasons for having an EMG

    This test can be useful in evaluating the cause of tingling, numbness, weakness, cramping or pain in the muscle.

    What is the procedure?

    EMG involves needle electrodes being inserted into the skin. The Neurologist places surface electrodes at various locations on your skin depending on where you are experiencing symptoms. The electrodes release a small impulse and the reaction in the muscle or nerve is recorded. The sensations you feel vary from person to person.

    The Neurologist will give you instructions on resting and contracting a muscle at appropriate times. Depending on what muscles and nerves the Neurologist is examining, you may be asked to change positions during the exam.

    How to prepare for the test;

    • Bring a list of your current medication.
    • Inform the Doctor or department if you are currently on aspirin or blood thinning agents (Warfarin or Clexane) or haemophilia.
    • Do not use any form of body lotion on the day of testing.
    • There is no need to fast on the day of testing.
    • Please inform the Doctor if you have a pacemaker or any other cardiac devices.

     

    After the test

    As with all needles, this can sometimes leave a bruise and the muscle may feel sore for a period after the test has been completed

    Results will not be available on the day. The consultant will report on the findings and this will be forwarded back to your referring doctor.

  • NCR is an abbreviation for nerve conduction studies. It is used to show how the body’s electrical signals travel along a nerve. During the test, a small electrode is placed on the skin of an arm or leg and the nerve is stimulated with a mild electrical impulse. This impulse travels along the nerve to the hand/foot where it is then measured.

    The test will take approximately 1 to 2 hours

    Reasons for having a NCS

    This test can be useful in evaluating the cause of tingling, numbness, weakness, cramping or pain in the muscle.

  • Visual Evoked Response (VER) measures electrical activity in the brain in response to stimulation of the optic nerve. Stimuli is delivered to the brain through evoked small electrical signals. 

     

    What is the procedure?

    1. This test takes approximately 30 minutes from start to finish.
    2. You will start by answering some routine questions from your Physiologist.
    3. You will be seated in front of a computer screen made up of a checkerboard and red dot in the centre. 
    4. You will be asked to watch a checkerboard pattern flash for several minutes on a screen and the electrical responses of the brain are recorded.
    5. Each eye is tested 3 times and your eyes are allowed to rest between tests. 
    6. Please ensure to bring your glasses or lens with you on the day.