Four Types of EEGs


By Lisa Marinelli Smith
NeuLine Health

Electroencephalograms, or EEGs, provide valuable information about our brain function by recording brain wave patterns.  

The brain creates electrical activity when neurons communicate and transmit the information to other nerve, muscle and gland cells throughout the body. 

The thousands of firing neurons create an electrical field strong enough that an EEG can record activity through the skull. Electrodes attached to the scalp, forehead and temples transmit the information. 

If brain waves and brain activity are irregular, neurologists will look for a cause, physical or psychological. Diagnosing epilepsy is the most common reason a health care provider will order an EEG. Seizures occur when electrical activity in the brain changes,

Other conditions evaluated with EEGs include: 

  • A head injury
  • Brain tumor
  • Chronic headaches 
  • Comas and brain activity 
  • Dementia
  • Dizziness
  • Sleep disorders
  • Stroke [If stroke blog is live, link to stroke blog.]

Your health care provider will order a specific type of EEG test to determine or rule out conditions. 

Routine or standard EEG test 

A routine or standard EEG is also called a baseline EEG. Here’s how it works: 

  • Once you’re set up with electrodes, a routine EEG lasts about 20-40 minutes. For some conditions, you may have an extended EEG that lasts closer to 60 minutes. 
  • During the test, you’ll be asked to rest quietly and open and close your eyes from time to time. You may also be asked to breathe deeply in and out for a few minutes, known clinically as hyperventilation. 
  • A flashing light may be placed near you at the end of the test to see how your brain reacts. Flashing lights can trigger seizures.

Sleep EEG or sleep-deprived EEG

Neurologists use EEGs as part of their tool chest to diagnose sleep disorders and sleep apnea. When health care providers are trying to diagnose epilepsy, they may also schedule an EEG to occur during sleep. 

According to the Epilepsy Foundation, an EEG while sleeping allows a more complete evaluation of brain activity and increases the chances of detecting an abnormality. 

If a doctor suspects epilepsy, but a standard EEG doesn’t offer enough information for a diagnosis, you may be asked to undergo a sleep or sleep-deprived EEG. 

  • For a sleep-deprived EEG, you will be asked to stay awake for 24 hours before the test to ensure you can sleep during the test. 
  • You may be allowed to nap for four hours during the 24 hours before the sleep-deprived EEG. 
  • You will also likely be asked to breathe deeply in and out (hyperventilate) and may be exposed to flashing lights. 

Epilepsy monitoring units 

In some cases, doctors will refer patients to epilepsy monitoring units, which are inpatient facilities that observe patients for several days using EEGs and video monitoring. 

Doctors refer people already diagnosed with epilepsy to test how medications are working. You may be asked to stop taking certain medicines before you check into the EMU. 

EMUs are also used to determine if someone has epilepsy in the first place. 

Patients usually stay from three to seven days at an epilepsy monitoring unit, and a friend or relative will need to stay with you. You will need to stay in bed while you are monitored. 

According to the National Association of Epilepsy Centers, patients in epilepsy monitoring units can expect: 

  • A comprehensive team approach to diagnose and treat epilepsy. 
  • The team will typically include epileptologists (neurologists with expertise in treating seizures), neurosurgeons, neuropsychologists, nurse specialists, EEG technologists and social workers. 
  • Their goal is to control or reduce the frequency of seizures and side effects for patients. 

Ambulatory EEG

Ambulatory EEGs give you the ability to stay in a familiar environment at home and have the EEG come to you. Your primary care provider or specialist can request an ambulatory EEG through NeuLine Health. 

A tech will come to your home, attach electrodes, set up the EEG and video monitoring equipment and give you instructions. In most cases, your test will last for 72 hours. At that point, the tech will come back to your house and remove the electrodes and equipment. 

A neurologist will read the EEG results and determine a diagnosis or decide if you need further testing.  

For more information about NeuLine Health EEGs, read about us online or call (844) 212-5321. 




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