EEG

An EEG is an investigation that measures the electrical activity of the brain. During this procedure electrodes are used to detect tiny electrical changes from brain cell activity and then amplified enough to take a graphical form. This graphical form is then interpreted by the healthcare provider in the context of signs and symptoms of disease. Many brain disorders and brain lesions can be detected with the help of EEG.

Why is an EEG test performed?

An EEG is used to diagnose a number of brain conditions including epilepsy and other seizure disorders. Some brain diseases that are diagnosed with EEG include:

• Sleep disorders
• Brain dysfunction secondary to encephalopathy
• Brain tumors
• Brain damage secondary to trauma and injury
• Stroke
• Creutzfeldt-Jakob disease
• Alzheimer’s disease
• Psychoses
• Narcolepsy
• Drug intoxication
• Coma
• Level of anesthesia

EEG test procedure

This test can be done as an outpatient or after the patient is admitted in the hospital. The procedure of EEG involves:

• The process starts by asking the patient to relax in a chair or bed.
• Around 16 to 25 electrodes are attached to the head of the patient.
• Thereafter, the patient is asked to relax, be still and close their eyes.
• For the duration of the exam, the patient should stay still. If the patient needs to be repositioned, the recording can be stopped periodically.
• After the recording is started, the healthcare provider tests the patient with various stimuli in order to stimulate brain activity that is not present at rest. These stimuli can include exposure to bright flashing light or deep breathing for at least three minutes.
• The procedure can take anywhere from 45 minutes to 2 hours and is done in the presence of the healthcare provider and EEG technician.
• For patients being evaluated for sleep disorders, EEG is performed while the patient is sleeping.
• Patients who need longer monitoring can be admitted to the hospital and 24-hour test can be done then.
• Ambulatory EEG is done in cases where prolonged monitoring after admitting the patient is not possible.

What happens after the EEG test?

After the investigation is complete, the electrodes are removed and the patient is allowed to rest until the effect of sedatives wears off. Any medication that the patient has stopped for the procedure can be continued thereafter. Depending on the particulars of the patient, the concerned doctor can give additional or alternate instruction for after the procedure.

What are the risks of EEG?

EEG is a relatively safe and painless investigation. In some cases, EEG can trigger seizure activity due to deep breathing or flashing lights during the test; however, these occur in the presence of medical help and can be treated immediately.

Over the years, this test has shown no discomfort to the patient, nor does it produce any sensation or electric shock. However, factors which can interfere with the results of EEG include:

• Hypoglycemia or low blood sugar, thus the patient should avoid fasting the day before and on the day of the procedure.
• Certain medications including sedative-hypnotics can interfere with the results and should be stopped beforehand.
• Excessive eye movement can cause erroneous results.
• Caffeinated drinks like tea, cola and coffee.
• Oily hair and use of hair spray.
• Flashing, bright lights.