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Electroencephalogram (EEG)

What is an electroencephalogram (EEG)?

An electroencephalogram (EEG) is a diagnostic test used to assess brain function and diagnose conditions affecting the brain by recording the electrical activity produced by neurons within the brain.

During the EEG, a technician places electrodes on a patient’s scalp. These electrodes are connected to a machine that records and monitors the electrical impulses generated as neurons communicate with each other. This recording provides valuable insights into the functioning of different areas of the brain.

The different types of EEG tests include:  

  • Routine EEG: Typically involves the patient looking at flashing lights or performing specific tasks for about 20 to 30 minutes.
  • Prolonged EEG: Lasts for an hour or longer to capture longer-term brain activity patterns.
  • Video EEG: Allows simultaneous video recording to correlate brain activity with physical movements or behaviors.
  • Ambulatory EEG: Records brain activity while the patient engages in daily activities, sometimes lasting for one or more days.
  • Sleep EEG: Conducted alongside a polysomnogram to monitor brain activity during sleep stages.  

An electroencephalogram (EEG) is used in several clinical scenarios to assess brain function and diagnose neurological conditions. Here are common situations when an EEG is used:

  • Seizures and epilepsy: EEGs are crucial in diagnosing and monitoring seizures and epilepsy. They help identify abnormal electrical activity in the brain that may indicate seizure disorders.
  • Evaluation of neurological symptoms: When patients present with symptoms such as memory loss, confusion, fainting, behavioral changes, or unexplained spells, an EEG can help determine if these symptoms are related to abnormal brain activity.
  • Monitoring brain activity: EEGs are used to monitor brain function in conditions such as Alzheimer’s disease, dementia, encephalitis, brain tumors, traumatic brain injury, and coma. They provide ongoing assessment of brain activity and response to treatment.
  • Surgical planning: Prior to brain surgery, especially for epilepsy or tumors near critical brain areas, EEGs help map brain function and identify areas responsible for critical functions like speech and movement.
  • Sleep disorders: EEGs are used with polysomnography (sleep study) to evaluate sleep disorders and abnormalities in brain activity during different stages of sleep.
  • Research and clinical trials: EEGs are also employed in research settings to study brain activity patterns associated with various neurological and psychiatric conditions, and in clinical trials evaluating new treatments.

Overall, EEGs play a crucial role in neurology by providing non-invasive insights into brain function and aiding in the diagnosis and management of a wide range of neurological disorders and conditions.