Understanding EEG Scan: What It Is and What It Can Diagnose

If you’ve been referred for an EEG test, you probably have some questions about what this test is, what it involves, and what it can reveal about your health. This article aims to shed some light on this test, exploring what it is used for, how it is performed, and what the results can show.

What is an EEG Test?

An EEG (electroencephalogram) test is a non-invasive diagnostic procedure that measures electrical activity in the brain. The test records the electrical signals that neurons (nerve cells) in the brain produce by tracking these signals across the scalp. This information can be used to detect abnormalities in brain activity, helping doctors to diagnose various neurological conditions.

What is EEG Test Used to Diagnose?

EEG tests are used to diagnose a range of neurological conditions, including:

  1. Epilepsy

    : A chronic disorder that causes seizures due to abnormal brain activity.

  2. Brain tumors

    : This test can help identify certain types of brain tumors by detecting changes in brain activity.

  3. Sleep disorders

    : EEG tests can be used to diagnose sleep-related conditions such as narcolepsy and sleep apnea.

  4. Developmental issues

    : EEG can detect certain developmental issues in newborns such as cerebral palsy and language disorders.

Abnormalities in EEG test results can also indicate other neurological conditions such as dementia, Alzheimer’s disease, and Parkinson’s disease.

How Long Does an EEG Scan Take?

An EEG test typically takes 30 to 60 minutes to complete, although the duration can vary depending on the nature of the test. Patients will be asked to lie down on a table or chair, with a technician attaching electrodes to their scalp. The electrodes are connected to a machine called an electroencephalogram, which records the brain’s electrical signals.

What Can an EEG Show That an MRI Cannot?

EEG and MRI are both diagnostic tools used to assess brain activity, but they function in different ways. MRI scans use magnets and radio waves to produce detailed images of the brain and can reveal structural abnormalities such as tumors or blood clots. EEG scans, on the other hand, measure electrical activity in the brain, focusing on how neurons communicate with one another.

EEG can detect certain conditions such as epilepsy, which are challenging to diagnose with MRI scans. Seizures happen quickly, and they are variable, often happening during the EEG test, making it much more effective in diagnosing this condition.

Which Is Better EEG or MRI?

There is no “better” diagnostic tool between EEG and MRI since they serve different purposes. EEG scans can detect problems with brain function while MRI scans can detect structural problems in the brain. Doctors will recommend one or both of these tests depending on the specific condition they are diagnosing.

10 Conditions Diagnosed with an EEG

Electroencephalogram or EEG is used to diagnose a range of neurological conditions, including:

  1. Epilepsy

    : irregular electrical activity in the brain can indicate epilepsy.

  2. Head Trauma

    : Brain injuries can result in seizures and abnormal EEG readings.

  3. Sleep Disorders:

    EEG can look for specific patterns in brain activity to diagnose sleep disorders such as sleep apnea and narcolepsy.

  4. Brain tumors

    : EEG can detect seizures caused by brain disorders such as tumors.

  5. TIA

    : Transient Ischemic Attacks or mini-strokes can precede a full stroke, and an EEG can indicate such risks.

  6. Encephalopathy

    : A brain disorder that affects cognitive function and can be diagnosed using EEG.

  7. Migraine

    : EEG can detect bursts of brain activity linked to migraines.

  8. Dementia

    : EEG can detect abnormal brain activity commonly associated with dementia.

  9. Creutzfeldt-Jakob Disease

    : EEG can detect certain patterns of brain activity that indicate the presence of this disease.

  10. Stroke

    : During a stroke, the brain can produce abnormal electrical signals, which can be detected using EEG.

EEG Test Results and Interpretation

An EEG test result that indicates “normal” means that no abnormal spikes or waves were detected in the brain’s electrical activity. If the test results are abnormal, meaning there are abnormal spikes or waves, it suggests that a condition exists.

Your doctor will explain the findings of the EEG test and explain what the results mean for your health. In some cases, further testing or treatment may be required.

How Long Is an EEG Test?

The length of the EEG test depends on the nature of the test being performed. A routine EEG test usually lasts between 30 to 60 minutes. Patients are required to remain still during the test and avoid any activities that can cause electrical activity in the brain in the meantime. For longer EEG tests such as 24-hour ambulatory EEG monitoring, patients may require a more extended period in the hospital.

EEG Test Full Form

EEG stands for Electroencephalogram.

EEG Test Side Effects

EEG tests are non-invasive procedures that are safe and free from potential risks. Some patients may find the electrodes and adhesive used to attach them to their head uncomfortable or itchy, but the sensations usually resolve once the test is completed.

EEG Scan Cost

The cost of an EEG test varies depending on the facility performing the test. In general, a routine EEG test costs between $200 and $700. More advanced EEG tests such as ambulatory EEG monitoring may cost several thousand dollars.


EEG tests are an essential diagnostic tool used to detect irregular electrical brain activity. The results of the test can aid in the diagnosis of a range of neurological conditions, including epilepsy, sleep disorders, brain injuries, and dementia. While the procedure itself is non-invasive, patients may need to avoid certain activities before the test, and the results may lead to further testing to determine treatment options.