Introduction
Interpreting a qEEG requires understanding the sequence of the various components involved in the Quantitative Electroencephalography (qEEG). It is a statistical method used to graphically represent the electrical activity of the brain following an electroencephalogram, or EEG recording.
1. Data Acquisition
Before qEEG processing can be used to analyze the data acquired from the brain, a recording of brain wave activity (EEG) must be done. The data can then be processed and analyzed by specialized QEEG computer software. The EEG recording may be done with individual electrodes placed on the scalp according to the International 10/20 System of Electrode Placement. (first illustration below). Alternatively a cap with embedded electrodes that conforms to the standard 10/20 System montage may be used. (second illustration below).This should be a painless procedure that takes about 40 min from set-up to clean-up. Different sized caps are used for different head sizes to ensure uniformity of EEG recordings from homologous locations on the scalp regardless of head size. This allows the electrical activity of the brain from different regions of the cortex to be statistically compared to normative databases.
2. Analysis of Brainwave Patterns
Different brainwave frequencies (delta, theta, alpha, beta, gamma) are associated with different states of consciousness, cognitive function, and emotional states. EEG analysis averages the amplitudes of all salient brain wave frequencies and creates a Fast Fourier Transform (FFT), which compresses a huge amount of EEG data into a graphic format of amplitude (or Power) vs frequency. These graphs are known as “EEG Spectral Plots.” An abnormal distribution or imbalance of these frequencies can indicate certain neurological or psychological conditions, which can be interpreted by an experienced QEEG expert.
Graphs of EEG Power Spectra
3. Mapping Brain Activity:
QEEG produces color-coded brain maps, which provide visual representations of brain activity and connectivity. Patterns such as focal slowing, asymmetries, excessive slow-wave or fast frequency activity can be readily detected when viewing the head map. In addition, neurological conditions like encephalopathy, traumatic brain injuries and stroke can be localized and referred out to a medical specialist.
QEEG Head Maps showing topographic distribution of EEG power at different frequencies in an 89 y/o normal individual (top) and a 77 y/o with memory loss and cognitive decline (bottom)” – these are the same head maps as appear in section #2 above
4. Comparison to Normative Databases:
QEEG data is often compared to age-matched, and sometimes sex-matched normative databases to identify deviations from typical brain activity patterns. This comparison helps identify abnormalities or deviations that may require further evaluation.
The “z-scores” are standard deviations (SD) from normal. The z-score legend shows +2 SD (higher than normal) in the red colored range, and -2SD (lower than normal) in the blue colored range. This set of head maps were derived from the 77 year-old patient with memory loss and cognitive decline. The maps illustrate that the patient’s slow frequency activity was much higher than normal in the Delta and Theta frequency ranges, and much lower than normal in the Alpha2, Beta1, Beta2, Beta3 and Gamma frequency ranges. These z-score comparisons show the extent of deviation in a patient who may be at risk for dementia.
Topographical head-maps show the distribution of EEG power in different frequency bands compared to age- and sex-matched controls.
5. Clinical Interpretation Should Only Be Done by a Well-Trained and Experienced qEEG Professional
QEEG interpretation should be done by a qualified healthcare professional, such as a neurologist, psychiatrist, or psychologist who is trained in reading and analyzing qEEG data. These professionals consider the overall clinical picture, the individual’s symptoms, medical history, and other diagnostic tests to provide a comprehensive assessment. Individuals who hold State Board Licenses to practice a psychological or medical discipline can be certified by the International QEEG Certification Board to qualify as EEG reviewers and qEEG professionals.The Board establishes rigorous criteria for training and mentoring before the individual can sit for the IQCB Board Certification Exam to earn the Diplomate certification in QEEG.
6. Diagnostic Insights:
QEEG can aid in diagnosing conditions such as epilepsy, head injuries, ADHD, Autistic spectrum disorder, mood disorders, sleep disorders, and other neurological or psychological disorders. It can also help monitor treatment progress and guide treatment decisions and medication management. A comprehensive clinical workup with a resting state EEG recording, a QEEG analysis, and clinical correlation with the patient’s presenting symptoms provides the necessary information to develop neurofeedback training protocols to optimize brain function and reduce or relieve symptoms.
7. Summary
In summary, interpreting a qEEG requires expertise in understanding brainwave patterns, interpreting brain maps, comparing data to normative databases, and integrating the findings into the larger clinical context to provide meaningful diagnostic insights. It is essential to consult with a qualified healthcare professional for an accurate interpretation and appropriate treatment recommendations. Dr. Mary Tracy at NeuroTraining Strategies is a Licensed QEEG Diplomate who has extensive experience and training in EEG and QEEG analysis. Her expertise includes offering didactic education in EEG and QEEG, Board certified online didactic courses, and private mentoring of individuals who wish to become trained and certified as QEEG Diplomates or Technologists. Check out our IQCB Board Certified 40-hour Didactic Course, the first step towards achieving Board Certification (insert link to QEEG course). [Insert photo of Mary preparing a client for an EEG recording from the home page].
