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Table of Contents
10-Plus Diagnoses
Reasons for an EEG
Interpreting Results
Anelectroencephalogram(EEG) is a noninvasive test that measures certain aspects of brain activity that reflect a person’s level of consciousness. It is used to diagnose epilepsy and certain types of brain damage and is part of apolysomnogram(comprehensive sleep study) that is used to diagnose sleep disorders.
Neurons communicate with each other through electrical signals. The EEG measures the synchrony and rhythm of electrical signals throughout the brain.
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10-Plus Conditions Diagnosed With EEG
An EEG test examines the rhythm of brain activity and the symmetry of nerve activity throughout the brain.The pattern of your EEG brain waves differs between waking and sleeping andcycles through stages while you’re sleeping.
Additionally, some medications, such as sedatives (medications that make you drowsy) and anesthetics (medications that reduce pain), can alter a person’s level of consciousness, which can be reflected in an EEG.
Severe brain damage, such as due to brain injury or oxygen deprivation, can cause EEG changes.
Seizures
Seizures and seizure-like conditions include:
Epilepsy SurgeryOften, a specialized EEG is necessary for identifying areas of the brain that can be targeted duringepilepsy surgery.
Epilepsy Surgery
Often, a specialized EEG is necessary for identifying areas of the brain that can be targeted duringepilepsy surgery.
Sleep Disorders
An EEG is part of a polysomnogram sleep study. This type of sleep study also involves monitoring your blood oxygen level, muscle movement, heart rate, and body temperature, which can help diagnose sleep disorders.
Sleep disorders that can be diagnosed with the aid of EEG include:
What Is an EEG Used For?
Prognosis
Sometimes an EEG is used as a medical assessment of severe brain damage to help in guiding prognosis and understanding expectations for recovery.
EEG uses in prognosis include:
What an EEG Cannot DiagnoseResearch experiments have used highly specialized EEG tests to study conditions such asschizophrenia,autism spectrum disorder,attention deficit hyperactivity disorder (ADHD), mood disorders, andmultiple sclerosis.While these investigations show subtle patterns that help in understanding the disease process, EEG is not used to diagnose or guide the treatment of these conditions.
What an EEG Cannot Diagnose
Research experiments have used highly specialized EEG tests to study conditions such asschizophrenia,autism spectrum disorder,attention deficit hyperactivity disorder (ADHD), mood disorders, andmultiple sclerosis.While these investigations show subtle patterns that help in understanding the disease process, EEG is not used to diagnose or guide the treatment of these conditions.
Research experiments have used highly specialized EEG tests to study conditions such asschizophrenia,autism spectrum disorder,attention deficit hyperactivity disorder (ADHD), mood disorders, andmultiple sclerosis.
While these investigations show subtle patterns that help in understanding the disease process, EEG is not used to diagnose or guide the treatment of these conditions.
Reasons a Provider Orders EEG
You or your loved one may need an EEG test if you’re being evaluated for possible seizures or an unexplained change in mental status. If you have a polysomnogram to evaluate a sleep disorder, an EEG is usually part of this test.
Timing of Test
The timing of an EEG test can be important, particularly in relation to sleep. Sleep deprivation can trigger a seizure in people who have epilepsy. An EEG that’s done for epilepsy evaluation may bemore likely to detect signs of epilepsy if a person has not had a full night’s sleep.
You may be instructed to stop taking certain medications prior to an EEG if those treatments are expected to make the results less reliable.
If you’re having a polysomnogram for evaluation of a possible sleep disorder, you may be asked to sleep as you normally do the night before your study and then to stay awake throughout the rest of the day before your evening sleep study.
Polysomnograms for some sleep disorders, such as narcolepsy, may be done during the day to assess daytime sleepiness.
EEG Accuracy
Anti-epilepsy medications can suppress seizure activity and may sometimes make it less likely to identify seizure patterns.
Drugs and alcohol can also alter EEG patterns, so EEG may be delayed until the effects of these substances wear off.
Interpreting Abnormal Results
The interpretation of an EEG study is very complex and requires specialized healthcare providers. Usually, an official EEG reading will not be available immediately because it takes time for a comprehensive review of the study.
Possible EEG results include:
Your EEG results can help guide the next steps in your care. If you’ve been diagnosed with epilepsy, the EEG results may help to determine medication choices or in planning epilepsy surgery.Additionally, if your healthcare providers are trying to distinguish between a movement disorder, migraine, or epilepsy, your EEG results can help in your diagnosis.
When EEG is done as part of a polysomnogram, diagnosis of your specific sleep disorder will aid in pointing to the right treatment. For example, obstructive sleep apnea is often treated with lifestyle measures anddevices that help to open the airways.Narcolepsy is treated with specific prescription medication.
If you or a loved one has had an EEG to assess changes in consciousness, the results can help determine prognosis and guide the discussion of how to proceed in light of the anticipated outcome.
Summary
An EEG is a noninvasive brainwave test that is used to evaluate and diagnose epilepsy, sleep disorders, and changes in consciousness. Sometimes EEG is necessary to help distinguish epilepsy from conditions that may have similar symptoms, such as movement disorders or migraine.
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National Institute of Neurological Disorders and Stroke.Epilepsy and seizures.
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