EEG-Based Brain Activity Assessment

Who this is for: Written for providers and patients who want a careful explanation of EEG-based assessment and its limits.

What brain-activity assessment records

The brain produces small electrical signals as it works. EEG-based assessment records those signals through sensors on the scalp, much as an ECG records the heart. The recording is passive. Nothing is sent into the brain, and there is no stimulation, no needles and no radiation. Analysis of the patterns adds standardized information about function that structural imaging and questionnaires do not capture.

Brain-activity findings are most meaningful as part of the whole picture.

The patient's experience

The patient sits in a comfortable chair while the technician fits a sensor cap or individual sensors, sometimes with a little water-based conductive gel. During the recording the patient may rest quietly with eyes open and then closed, or do a simple task. Staying relaxed and still produces the best recording. Afterward the gel wipes or washes out. Most patients find it the most restful part of the visit.

How to prepare

Arrive with clean, dry hair and no heavy oils, sprays or styling products. Mention braids, weaves, extensions or head coverings when scheduling so the technician can plan sensor placement respectfully. Take your usual medications unless your own provider advises otherwise, and tell the technician what you took that day, since some medications can affect the recording.

Related in this series: EEG-Based Brain Activity Assessment: The Basics, Research Summaries (Plain-Language) and Our Diagnostic Standards & Privacy. For the full overview, start with our guide, TBI Diagnostics: What Tests and Reports Show.

How results are interpreted

The recording is processed and compared with reference patterns, and a neurologist interprets it alongside eye-movement findings, neurocognitive scores and the symptom history. EEG measures are one part of a multi-domain evaluation and are not used on their own to diagnose concussion. Professional guidelines, including the ACNS 2021 guideline, consider quantitative EEG investigational, and our reports present it as an adjunct, never a stand-alone answer.

Most patients find it the most restful part of the visit.

What it doesn't do

The assessment does not read thoughts, detect lies or reveal personal information. It measures general patterns of electrical activity. Nor is it an emergency test. It is for evaluating ongoing symptoms in a stable patient.

Where it fits in care

For the treating provider, brain-activity findings add one more standardized layer to consider when deciding about specialty referral, such as neurology, and activity planning. We diagnose. You treat.