By Adrian Sparrow
NeuLine Health

The brain is a fascinating organ capable of monitoring changes in the body and adapting to its environment. It has a constant stream of electrical activity between neurons, and this activity can be recorded in waveforms. 

An electroencephalogram, or EEG, is a test that uses small metal discs, called electrodes, that attach to your scalp to record brain wave activity. Electrical changes are recorded on a graph, either on a computer screen or paper, as the test is performed. Depending on the patient’s circumstances, their healthcare provider may use stimuli like sounds or flashing lights to measure the brain’s response. 

What an EEG Tests For 
An EEG detects changes in brain activity that can be used to diagnose several kinds of brain disorders.



-Brain damage from head injuries

-Inflammation (encephalitis)


-Sleep disorders


An EEG can also be used to evaluate brain damage in coma patients, evaluate trauma or level of drug intoxication, and monitor blood flow during surgery. 

What Happens During an EEG?

This test is considered a safe procedure, performed for many years. There is minimal risk associated with EEG. The electrodes do not produce any sensation, and the patient has no chance of receiving an electric shock. There may be risks associated with the patient’s specific medical condition, which the healthcare provider will discuss before the exam.

A routine EEG typically takes place in an outpatient setting. Electrodes are placed on the scalp and will remain for the test duration, typically between 30 minutes to 2 hours. The patient will need to stay still and relax. They may be asked to breathe deeply or look at a flashing light, which can change the brain’s electrical activity and potentially induce a seizure. If a seizure does occur, which is sometimes the purpose of these tests, the healthcare provider will treat it immediately. 

Some EEG tests may take place over several hours or days or overnight if the patient is being evaluated for a sleep disorder. Prolonged EEG monitoring may occur once the patient is admitted to the hospital, or perhaps an ambulatory EEG- performed in the comfort of home- may be performed, with or without video recording. In each situation, the doctor may instruct whether to stop or reduce medication for the duration of the test. 

After the test has been completed, the technician will carefully remove the electrodes from the scalp and wash the electrode paste with warm water or acetone. Skin irritation may be present where the electrodes were placed, but this will wear off. From there, the patient’s healthcare provider may give additional instructions regarding medication or follow-up.

Results will usually take a few days or weeks to be studied by the EEG technician and then sent to the prescribing physician. They may order another EEG or make a diagnosis from the results and the patient’s medical history. The physician will then discuss the results and next steps, possibly including treatment, with the patient.