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EEG Department

The EEG technologists at Mercyhealth are trained medical personnel who prepare the patient for a test, operate the equipment, and prepare data for physicians to interpret.  The technologists perform Electroencephalogram (EEG) and Evoked Potentials.

A physician may order some of the tests below:

Electroencephalogram (EEG)
An Electroencephalogram (EEG) is a painless procedure that uses small flat metal discs called electrodes that are attached to your scalp with a paste.  An EEG detects electrical impulses in the brain and creates a wave pattern that can be shown on a computer screen.  These electrical impulses carry messages to and from all parts of the body through the nervous system. A healthy person produces certain wave patterns.  When a person is ill or injured, the electrical messages may become blocked or altered which can cause a change in the wave pattern.  This can be used to determine the location of a problem and its cause.

An EEG can help diagnose, monitor or rule out:

  • Brain death
  • Brain tumor
  • Brain injury
  • Degenerative disorders (Alzheimer’s, Parkinson’s)
  • Encephalitis (brain inflammation)
  • Epilepsy
  • Headaches
  • Metabolic disorders (liver, kidney)
  • Seizure disorders
  • Stroke

An EEG does not:

  • Treat or cure illness
  • Read your mind
  • Tell the technologist what you are thinking
  • Measure intelligence
  • Detect mental illness unless there is a physical cause
  • Give you a shock

Preparing for the EEG

  • Arrange for someone to drive you to and from the EEG facility
  • You may be asked to adjust your sleeping schedule
  • Do not have caffeine (tea, coffee, cola, energy drinks) or chocolate the day before your test
  • You may eat breakfast the day of the test unless instructed otherwise
  • Continue to take your regular medications unless instructed otherwise
  • Arrive for your test with clean, dry hair without hairspray, gel, or mousse
  • If coming in as an outpatient, arrive 15 minutes before your appointment to Admitting to register

 What Will Happen During Your EEG

  • A routine EEG test takes about 90 minutes to perform, but may run shorter or longer than this time frame
  • You may be called the night before to be pre-registered for the procedure and given instructions
  • You may be ordered to take a medication (mild sedative) – this will be reviewed by the ordering physician
  • The technologist will ask you what happened and for some history
  • The test will be explained and you will be asked to lie on a bed
  • The technologist will measure and mark your head for electrode placement
  • Your scalp is scrubbed with a gel to remove any oil
  • Small discs (electrodes) are attached to your scalp with a paste and a headband is used to hold them in place
  • Additional information

During the Test

  • You may fall asleep during part of the test
  • Hyperventilation – You may be asked to breathe rapidly and deeply through the mouth – the technologist will review with you
  • Photic Stimulation – a flashing light may be placed in front of your closed eyes
  • Your cooperation during the test is important.  The more relaxed you are, the more accurate the results will be.  Stay quiet and lay still.  Avoid a lot of movement or tightening your muscles.  Follow instructions during the test.

Other EEG Tests

Evoked Potentials

Evoked Potentials (EPS) are electrical responses of the nervous system to specific stimuli.  These responses are displayed and analyzed by a special computer.  These responses are then interpreted by a physician trained to read Evoked Potentials.

Types of Evoked Potentials

  • Visual Evoked Potentials – analyze the visual (seeing) nervous system and look for optic nerve disorders.  Electrodes will be attached to your scalp with paste.  You will be asked to stare at a flashing light or a pattern on a TV screen.  The light or pattern is used as a stimulus.
  • Brainstem Auditory Evoked Potentials – analyze the auditory (hearing) nervous system to look for auditory and brain diseases.  Electrodes are attached to the scalp with paste and an electrode to each ear.  Ear phones are placed over the ears and deliver a series of tones or clicks to each ear separately.  The sound is the stimulus.

After the EEG/Evoked Potentials

  • The technologist will tell you when it is over.
  • The technologist will remove the electrodes with warm water.
  • You may want to wash your hair either at the EEG facility or at home as the paste will leave a residue in your hair.  (Warm water; shampoo a minute; warm water rinse).  You may bring a hat to wear after the procedure to cover your hair.
  • Normal activities may be resumed unless you are told to restrict activities.
  • Your health care physician will receive the results – the technologist cannot discuss the results with you.
  • Your health care provider will review the results with you within seven to 10 business days and may schedule an office appointment to discuss the results of the test.  If possible, bring along a family member or friend to help you absorb all of  the information.

If you have any questions, please don’t hesitate to ask.

EEG Department Locations