QEEG After a Concussion: What Quantitative EEG Adds, and Where It Stops

Who this is for: Attorneys reviewing a client's diagnostic record, providers deciding whether a QEEG finding should change a plan, and patients who saw "QEEG" on a report and want to know what it means.

If you have already read our EEG-based assessment basics, you know what the recording session is like. This article is about the next step: what happens when that recording is turned into numbers, and how much those numbers should be trusted.

From a recording to a quantitative profile

A conventional EEG is read visually: a trained reader looks at the waveforms for clearly abnormal patterns. After most concussions, the visual read is normal. Quantitative EEG, or QEEG, takes the same recording and applies analysis to it. Common measures include how much activity falls in each frequency band, how activity compares between the two sides of the brain, and how closely different regions appear to work together.

Those values are then compared with reference data from people of similar age. The output is a profile showing where a patient's measures fall relative to that reference range.

What QEEG can add

Concussion is a functional injury. Structural imaging such as CT is usually normal, which we explain in why a CT scan can miss a concussion. A quantitative brain-activity measure offers a different kind of information: a standardized look at function, recorded the same way each time.

That can help in three practical ways:

• Context for symptoms. When a QEEG profile is consistent with reported problems such as slowed thinking or poor concentration, the neurologist has one more data point to weigh.
• A baseline for follow-up. Because the method is standardized, a repeat recording can be compared with the first.
• A prompt for next steps. Findings may support a referral for further evaluation or advanced imaging, at the treating provider's discretion.

A QEEG number is a measurement, not a conclusion. Its meaning comes from the clinical picture around it.

The honest limits

The research is real, and so are its gaps. A 2019 systematic review of resting-state EEG after sport-related concussion found differences between concussed and control groups in many studies, but also wide differences in methods and analysis that limit firm conclusions. A 2023 systematic review on QEEG in TBI described accumulating evidence for its objectivity and reliability while noting that the field still depends heavily on how the data are collected and analyzed.

In plain terms:

• Many factors can shift QEEG values, including drowsiness, medication, anxiety, prior conditions and recording quality.
• An unusual value does not, by itself, show that an injury occurred or what caused it.
• A value within the reference range does not rule out a concussion.
• Professional neurology societies have long cautioned against using QEEG as a standalone diagnostic tool.

That is why Braintree uses brain-activity measures only as part of a multi-domain evaluation alongside eye-movement testing, neurocognitive testing and the patient's history.

For attorneys: reading QEEG in a record

When QEEG appears in a client's file, the useful questions are about context rather than the number itself. Was it interpreted by a physician? Is it discussed together with other findings, or presented alone? Does the report state its limits? Physician-reviewed diagnostic reports that place QEEG alongside other measures tend to be clearer for everyone who reads them. Our attorney resources and sample report walkthrough show how findings are organized.

For providers: when a QEEG finding should matter

Treat QEEG as corroborating information. It matters most when it agrees with the symptom history and other objective measures, and least when it stands apart from them. Braintree sends the reports to a neurologist who interprets them, and you receive a copy to inform imaging and treatment decisions. We diagnose. You treat.

For patients: what to take from your result

If your report mentions QEEG, it is one of several measures your neurologist considered. Ask your provider how it fits with the rest of your evaluation, and keep reporting your symptoms honestly. How you feel and function remains central to your care.