What is an EEG?
An EEG test identifies abnormalities in your brain waves or electrical brain activity. Small metal discs with thin wires are applied to the patient's scalp during the procedure. The electrodes detect the minute electrical charges generated by brain cell activity. The amplified charges are displayed as a graph on a computer screen or as a recording that can be printed on paper. Your physician will then interpret the results.
During an EEG, your physician will typically evaluate approximately 100 pages or computer screens of activity. In addition to focusing on the fundamental waveform, they examine transient energy surges and responses to stimuli, such as flashing lights.
Studies of evoked potential are related procedures that may also be performed. These investigations measure electrical activity in the brain in response to visual, auditory, or tactile stimulation.
Why may I require an EEG?
The EEG is utilized to diagnose a variety of neurological disorders. Seizure activity will appear as rapid spiking waves on the EEG when epilepsy is present.
Depending on the size and location of the lesion, people with brain lesions, which tumours or strokes can cause, may exhibit abnormally sluggish EEG waves.
The test can also diagnose other conditions that affect brain activity, such as Alzheimer's disease, specific psychoses, and narcolepsy, a sleep disorder.
In addition, the EEG can be used to ascertain the overall electrical activity of the brain (for instance, to evaluate trauma, drug intoxication, or the extent of brain damage in comatose patients). During brain surgery, the EEG may also be used to monitor blood flow in the brain.
What are the risks associated with an EEG?
The EEG has been used for decades and is considered a safe technique. The test does not induce discomfort. The electrodes are used to detect activity. They do not affect the senses. Additionally, there is no danger of electrical shock.
Rarely an EEG can induce seizures in individuals with a seizure disorder. The test may involve flashing lights and deep respiration.
Depending on your specific medical condition, additional risks may be present. Before the procedure, discuss any concerns with your healthcare provider.
Certain factors or conditions may interfere with the accuracy of an EEG reading. These consist of:
- Movement of the body or eyes during the tests will rarely, if ever, substantially impact the interpretation of the test.
- bright or flashing lights
- Certain medications, including sedatives
- Caffeine-containing beverages
- oily hair or the presence of hairspray
How should I prepare for an EEG?
Ask your healthcare provider what you need to do before your examination. Below is a list of typical tasks you may be required to complete.
- Your healthcare provider will explain the procedure, and you are welcome to ask any questions
- You must execute a consent form before the process can begin.
- Shampoo your hair the night before the exam, but do not apply conditioner. Avoid using hair care products such as hairspray and gel.
- Inform your healthcare provider of all prescription and nonprescription medications and herbal supplements you are consuming.
- If your healthcare provider instructs you to do so, you should stop taking any medications that may interfere with the test. Do not cease taking your medications without first consulting your doctor.
- Caffeine-containing foods and beverages should be avoided 8 to 12 hours before a test.
- Follow your healthcare provider's instructions regarding sleep restriction the night before a test. Some EEG examinations require you to sleep during the entire procedure, while others do not. If the EEG is to be performed during sleep, adults may not be permitted to sleep more than 4 or 5 hours the night prior. Children should not be
- allowed to slumber the night before for more than 5 to 7 hours.
- Do not fast the night back or the day of the procedure. Low blood sugar levels may impact the results.
What happens during an EEG?
An EEG may be performed on an outpatient basis or as part of a hospital stay. Procedures may vary depending on your condition and your healthcare provider's practices. Discuss with your healthcare provider what you can expect during the test.
Generally, an EEG procedure consists of the following steps:
- You will be instructed to recline in a recliner or lie on a bed.
- With a special paste, between 16 and 25 electrodes will be affixed to your scalp, or a cap containing the electrodes will be worn.
- You must close your eyes, relax, and remain still.
- Once the recording begins, you must stay still for the exam. Your healthcare provider may monitor you through a window in an adjacent room to observe any movements, such as inhaling or blinking, that could result in an inaccurate reading. The recording may be paused periodically to allow you to recover or adjust your position.
- After obtaining an initial recording of your brain waves while you are at rest, your healthcare provider may subject you to various stimuli to elicit brain wave activity that is not present when you are at rest.
- An EEG technician typically conducts this investigation, and it can take between 45 minutes and two hours.
- The EEG may be performed while you sleep if you are being evaluated for a sleep disorder.
- You may be admitted to the hospital for prolonged EEG (24-hour EEG) surveillance if you need to be monitored for an extended period.
What happens after an EEG?
After the test, the electrodes and the electrode paste will be removed using running water or acetone. In certain instances, you may have to cleanse your hair again at home.
If you took sedatives for the examination, you may be required to rest until the sedatives wear off. Someone will need to take you home.
There may be skin irritation or discolouration at the sites where the electrodes were placed, but this will subside within a few hours.
Your healthcare provider will advise you when you may restart taking any medications you discontinued before a test.
Your healthcare provider may provide additional or alternative post-procedure instructions based on your circumstances.