Of the eight imaging types in this series, quantitative EEG is the only one that is not imaging at all. It records electrical activity rather than producing a picture, and it is the only study in the protocol with millisecond time resolution.
It is also the one where I have to give you a professional guideline that runs against the way it is usually marketed, so let me do that early rather than bury it.
How Is a qEEG Recorded?
A standard EEG cap with surface electrodes records the brain's electrical rhythms from the scalp. That part is ordinary clinical neurophysiology and has been for decades.
The quantitative layer is what comes after. Software decomposes the recording into frequency bands — delta, theta, alpha, beta, gamma — measures the power in each, measures coherence between regions and between hemispheres, and compares all of that against a normative database of recordings from people without known neurological disease.
The output is not a picture of your brain. It is a set of numbers describing how your electrical activity compares to a reference population.
What Patterns Show Up After a Head Injury?
The patterns reported in the traumatic brain injury literature are reasonably consistent in direction: increases in slow-frequency activity, particularly delta and theta, alongside decreases in faster activity in the alpha, beta, and gamma bands, plus abnormal variability in power and disrupted coherence between regions (Amico & Koberda, 2025).
Excess frontal theta and alpha slowing are the specific findings named most often, and they correspond in a broad way to the complaints people report — slowed processing, difficulty sustaining attention, reduced cognitive stamina.
That review examined 31 articles and concluded that qEEG "may improve the diagnosis and management" of traumatic brain injury. Note the hedge in that verb. It is doing real work.
What Does the Practice Guideline Say?
Here is the part that has to be stated plainly.
The American Clinical Neurophysiology Society published a practice guideline on the use of quantitative EEG for diagnosing mild traumatic brain injury. Its recommendation is that **the evidence does not support the clinical use of qEEG, either at the time of injury or remote from it, to identify patients with mild traumatic brain injury.** It assigns that recommendation Level U — insufficient evidence to support or refute.
The same guideline states that qEEG remains investigational as a diagnostic tool for mild traumatic brain injury on Class III evidence, that there have been no well-designed studies of qEEG-related methods for this diagnosis, and that the review revealed a dearth of evidence-based qEEG diagnostic techniques for identifying individuals with the condition (Tenney et al., 2021).
That is a society practice guideline. It carries considerably more weight than a systematic review in a specialty journal, and it should govern how anyone talks about this study — including me.
I have said in teaching settings that qEEG is one of the more useful tools for tracking treatment response over time. I want to correct that here rather than leave it standing. I could not find evidence supporting the treatment-tracking claim to a clinically actionable standard, and the guideline states that no well-designed diagnostic studies exist. What I have is a clinical impression that the numbers move when patients improve. A clinical impression is not the same thing as a validated outcome measure, and I should not have presented it as more than it is.
Then Why Is It in the Protocol at All?
Because "not validated as a diagnostic" and "measures nothing" are different statements, and the distinction is the whole of my position.
Surface EEG measures genuine electrical activity. That is not in dispute and never has been. What the guideline rejects is the inferential step: that a pattern in those numbers can be used to establish, in an individual person, that they have or do not have a mild traumatic brain injury.
I agree with the guideline on that step. Nobody should be told they have a concussion because a qEEG report says so, and nobody should be told they do not.
What I use it for is narrower:
**As a baseline.** A recording taken before treatment gives you something to compare against later. Whether the comparison is meaningful is exactly the open question above, but you cannot compare against a baseline you never took.
**As a convergence check.** No single study in this protocol carries a diagnosis. When a qEEG pattern of frontal slowing lines up with a perfusion pattern in the same territory, a symptom picture that matches both, and structural findings at the [craniocervical junction](condition-craniocervical-instability.html), the agreement across independent methods means more than any one of them.
**Because it is non-invasive and involves no radiation.** The cost of ordering it is low, which changes the calculation relative to studies that carry a dose.
That is my clinical reasoning, presented as reasoning rather than as evidence.
Does This Help Separate a Brain Problem From a Neck Problem?
Less cleanly than the other brain studies, and I would rather say so than overclaim.
Electrical activity recorded at the scalp is cortical. It tells you something about how networks are behaving. It does not tell you why they are behaving that way — a cortex can be underperforming because the tissue is injured, or because its blood supply and drainage are compromised, or because the signal reaching the brainstem from below is unreliable. The recording looks similar in all three cases.
So qEEG on its own does not adjudicate between a brain problem and a neck problem. What it can do is establish that something measurable is different, which matters enormously for a patient who has been told repeatedly that every test is normal.
The adjudication comes from the rest of the protocol. If a patient shows a qEEG abnormality alongside a structurally unremarkable craniocervical junction, normal fluid dynamics, and no position-dependent neurological findings, I am looking at something that is probably not mine to treat — and I should say so and refer, [because sometimes there really is a problem inside the brain](post-what-spect-shows-about-blood-flow-in-an-injured-brain.html).
What Should You Expect From a qEEG Report?
If someone hands you a colored map of your head with regions marked in red and tells you what diagnosis it demonstrates, you are being oversold.
A defensible report states what was measured, how it compares to the normative database, what the confidence intervals are, and what it does not establish. It should be one page in a folder alongside several other studies, not the centerpiece.
It is also worth asking which normative database was used and whether your age group is adequately represented in it, since the comparison is only as good as the reference population.
Have You Been Told Every Test Was Normal?
If your structural imaging came back clean and you are still unable to sustain the cognitive work you used to do without difficulty, a recording that measures electrical function is asking a different question — even though, on its own, it will not give you a diagnosis.
Ordering it deliberately, reading it alongside everything else, and being straight with you about what it does and does not establish is the work we do at Cerebral. If you'd like a real evaluation, we're here.
References
- Tenney JR, Gloss D, Arya R, et al. Practice guideline: use of quantitative EEG for the diagnosis of mild traumatic brain injury. Report of the Guideline Committee of the American Clinical Neurophysiology Society. *Journal of Clinical Neurophysiology*. 2021;38(4):287–292. https://doi.org/10.1097/WNP.0000000000000853
- Amico F, Koberda JL. Quantitative electroencephalography objectivity and reliability in the diagnosis and management of traumatic brain injury: a systematic review. *Clinical EEG and Neuroscience*. 2025;56(5):432–445. https://pubmed.ncbi.nlm.nih.gov/37792559/
- Wortzel HS. Advanced neuroimaging and mild traumatic brain injury litigation, revisited. *Journal of the American Academy of Psychiatry and the Law*. 2022;50(3):336–341. https://jaapl.org/content/50/3/336
- Eierud C, Craddock RC, Fletcher S, et al. Neuroimaging after mild traumatic brain injury: review and meta-analysis. *NeuroImage: Clinical*. 2014;4:283–294. https://pubmed.ncbi.nlm.nih.gov/25061565/