What is a Quantitative EEG (qEEG)

Comparison to Conventional EEG

Conventional (clinical) EEG, is often utilized by neurologists using visual inspection of the EEG to discern patterns, particularly of the shape or morphology of the brain waves. QEEG analysis may include that kind of evaluation, but is different in that it provides additional quantified measures of the EEG using modern computers.

Measures of the qEEG

The EEG records rhythmic changes of the brain cells near the scalp. The Quantitative EEG sorts and quantifies the different cycles into individual frequencies or bands of frequencies. All 19 locations measured around the scalp can be quantified simultaneously - in effect making a map of the neuronal activity of the whole outer surface of the brain. Beyond just averaging quantities, a qEEG can reveal how the different frequencies are related to each other at a specific location and how the locations are inter-relating with each other across the whole map of the brain.

Normative Databases

Through all of human health care, we use measures of biological constituents or functioning to provide insight. We have normal values for body temperature, blood constituents, heart, lung, or kidney functioning and many more parameters. Over years of research, scientists have developed databases of normal and abnormal brain wave functioning using the same international scalp location system. A qEEG reveals where the individual's EEG significantly differs from age-matched normative values. It provides a map of the underlying, invisible, and otherwise unquantified measures of neuroelectric anomalies.

Clinical uses of the qEEG

A qEEG analyses is not used as the sole basis for making a diagnosis. A qEEG is not a substitute for clinical judgment or expertise. It is an objective, normative assessment that can be utilized in a way congruent with the professional's observations when planning treatment. It can reveal more specific details of brain dysfunction.

qEEG guided Neurofeedback

Neuroelectric behaviors of the brain can be increased or decreased through the use of instantaneous, consistent, and clear feedback specific to those behaviors. The brain has a lifelong ability to reorganize neural pathways based on new experiencing. A return of lost function is possible. So too is a gain of new functioning. In the big picture, a brain can be capable of increased flexibilty and resilence in its state conditions and responses as the individual meets their life's challenges. This is the efficacy of neurofeedback.

qEEG guided neurofeedback targets the most significant deviations from normal - often two or more standard deviations from normal. It is through the exercising of the brain in those specific neuroelectrical deviations that "normalization" may most efficiently occur.

"A Neurologist's Experience with qEEG-Guided Neurofeedback Following Brain Injury"

"When there is severe injury to the brain, with development of hemorhage or brain edema, it is easy to diagnose with CT scan or MRI or raw EEG. However in the majority of cases (over 85 percent), those routine studies are normal even when the patient has severe postconcussive sequelae. The gold standard for determining brain injury is the quantitative EEG. The most common abnormalities on qEEG in "mild" closed head injury (i.e. , patients who are alert and have no focal neurological deficits) are increase in coherence of theta and beta, decrease in phase of beta and alpha, beta amplitude asymmetries, and decreases in relative power of alpha." - Jonathan E. Walker M.D.

-from Chapter 15 of Evans, James R. (Editor) (2009)Handbook of Neurofeedback: Dynamics and Clinical Applications New York: Informa Healthcare USA, Inc.

- with specific reference to: Thatcher, R.W., Walker, R.A., Gerson, I, & Geisler, F. (1998) EEG discriminant analyses of mild head trauma. Electroencephalography and Clinical Neurophysiology, 73, 94-106