Electroencephalogram (EEG)

EEG monitoring evaluates seizures and neurological and behavioral disorders. The results are used to plan appropriate treatment for the patient.

During an EEG, electrodes are placed on the scalp over multiple areas of the brain to detect and record patterns of electrical activity and check for abnormalities. Brain cells communicate by producing tiny electrical impulses and an EEG can record these communications.

The test is performed by an EEG technologist in a specially designed room that may be in your health care provider’s office or at a hospital. The technologist will apply between 16 and 25 flat metal discs (electrodes) in different positions on your scalp. Held in place by a paste, the electrodes are connected to the EEG machine. The EEG records brain activity. The recording machine converts the electrical signals produced in your brain into an image of wavy lines that are drawn onto a moving piece of graph paper.

A routine EEG will take approximately one hour to complete. In some cases, a longer period of monitoring may be required. Patients are sometimes monitored for a length of time determined by the doctor, usually 23 to 72 hours.

Sometimes the patient is asked to perform certain actions during the recording, such as breathe deeply and rapidly for several minutes or look at a bright flickering light.

The recording is then evaluated by a neurologist and an appropriate course of treatment will be determined.

Possible reasons for an EEG

There are many reasons a doctor may recommend that a patient undergo an EEG, such as:

  • To diagnose epilepsy
  • To determine the type of seizures a patient is experiencing
  • To establish if a patient is having problems with loss of consciousness
  • To reveal whether any sleep disorders exist
  • To determine if a patient’s problem is physical in nature (e.g., brain, spinal cord, etc.) or a mental health problem