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EEG
General · N/A
Available at 0 labs
No lab currently offers this test.
About this test
What is an EEG?
An electroencephalogram (EEG) is a non‑invasive test that records the electrical activity of the brain using electrodes placed on the scalp. It helps doctors understand how brain cells are communicating.
Key parameters
| Parameter | What it shows |
|---|---|
| Waveform pattern | Overall brain activity and rhythm |
| Frequency bands (delta, theta, alpha, beta, gamma) | Different states of alertness, sleep, or abnormal activity |
| Amplitude | Strength of electrical signals |
| Inter‑electrode latency | Timing differences between brain regions |
Why is it done?
- To evaluate seizures or epilepsy
- To investigate unexplained headaches, dizziness, or fainting
- To assess brain function after head injury or stroke
- To monitor brain activity during sleep studies
- To screen for brain disorders in patients with neurological symptoms
Early detection
An EEG can help identify signs of epilepsy, encephalopathy, or other neurological conditions, but it does not diagnose on its own. A doctor interprets the result together with symptoms, history, and other tests.
What abnormal results may mean
- Increased slow waves can suggest brain injury, infection, or metabolic issues.
- Spike‑and‑wave patterns are often seen in epilepsy.
- Asymmetry between hemispheres may indicate a lesion or tumor. Many factors—medication, caffeine, sleep deprivation, or stress—can affect the readings.
Who might need an EEG?
- People with recurrent seizures or suspected epilepsy
- Individuals with unexplained neurological symptoms (e.g., fainting, headaches)
- Patients recovering from brain injury or stroke
- Those undergoing sleep disorder evaluation
In short: An EEG records brain waves to help doctors spot abnormal electrical patterns that may indicate neurological problems.
Used for detecting / monitoring
EpilepsyEncephalitisBrain DeathCerebral PalsyMeningitisSubarachnoid HemorrhageCreutzfeldt-Jakob Disease
Before your test
Preparation
- Fasting: Not required for an EEG.
- If combined with fasting tests: Follow the strictest instruction (e.g., if you are also having a blood test that requires fasting, fast for the required period).
- Procedure: Electrodes are gently placed on the scalp using a conductive gel. The test usually lasts 20–30 minutes, sometimes longer if a sleep study is included.
- What to expect: No needles or pain. You may feel a slight pressure from the electrodes.
- Precautions: Avoid heavy exercise, alcohol, or caffeine 24 hours before the test if you are concerned about their effect on brain activity.
- Final note: Confirm specific preparation with your doctor or the lab. This information is educational and not a substitute for professional medical advice.
Sample type: N/A
Report parameter guide
EEG Result
Overall assessment of brain electrical activity
Frequently asked questions
An EEG records the electrical activity of the brain using electrodes on the scalp, showing waveform patterns, frequency bands, amplitude, and timing differences between regions.