Neurophysiology
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Useful Information
About our services
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)
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 one to one and a half 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 two 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.
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.
Nerve conduction studies (NCS) are 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 one to two 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.