What is a QEEG?
A QEEG is a non-invasive, scientific, evidence-based assessment tool that is used to identify
areas of dysregulation in the brain that can cause symptoms such as sleep disturbance, emotional
or behavioural difficulties, and learning difficulties.
EEG (electroencephalogram) measures electrical activity occurring in the brain using electrodes placed on the scalp. The QEEG (Quantitative Electroencephalogram) process analyses this digital EEG recording, compares certain factors in the EEG to the norm for the client’s age and gender, and generates topographic maps of brain function. These maps identify brain regions that are not producing optimal activity.
Various factors are investigated in a QEEG that comprehensively contribute to greater understanding of the cause the presenting difficulties and can assist in devising an effective plan for remediation:
- absolute power
- relative power
- power ratios
Deviations are presented as z-scores i.e. as standard deviations from the norm. This is not normal / abnormal, rather how deviant from the norm the value is.
- ABSOLUTE POWER: is a direct comparison to the norm matched for age and gender.
- RELATIVE POWER: How much of the pie does each frequency take up?
- ASSYMETRY: gives an indication of mood disturbance.
- COHERENCE: How efficient is neuronal firing within brain networks?
- POWER RATIOS: How much amplitude of one frequency is there to balance how much amplitude of another frequency?
A QEEG measures the electrical functioning of the brain and not the structure. This electrical
activity is measured while the brain is at rest, and while cognitively involved in various tasks to
ensure that the correct parts of the brain are engaged at the correct time.
This tool is not intended to be used in isolation for diagnosis or to replace the medical opinion of a physician, neurologist or other professional, but rather as part of a comprehensive assessment of functioning. It is also helpful when tracking changes in brain function as a result of intervention, such as neurofeedback or medication.
QEEG has “a level of specificity and sensitivity that is comparable to sonograms, blood tests, MRIs and other diagnostic measures commonly used in clinical practice.” (Thatcher, Moore, John et al, 1999).
Relevant Brodmann areas are also explored in the QEEG summary report that will be provided.
What happens during a QEEG? What preparation must be done beforehand?
The QEEG process should take 45 minutes – 1 hour. 20 electrodes will be placed on the scalp with paste as well as one on each earlobe and one on each pulse point on the wrist to measure cardiac rhythm. Each area will first be cleaned with abrasive gel and an earbud. It is a painless process.
During the recording itself, it is necessary to sit very still and relax for an accurate recording. It is possible to stop the recording to allow the patient to move around before continuing again. Some of the recording will be done with eyes open and some with eyes closed. While eyes are closed, a light will flash for a short while (photic stimulation) and thereafter the patient will be asked to breathe deeply and rapidly (hyperventilation) to record changes, if any, in the EEG as a result of these. Once enough EEG has been recorded (usually 20 minutes), the electrodes will be removed. Some paste will still remain in the hair.
If medication is taken that may alter the results of the QEEG, it is advisable to skip a few doses so it can be completely out of the system before the QEEG is done. Stimulants, such as Ritalin and Concerta, should not be taken for 48 hours before the test. Sleep aids (including herbal remedies) should not be taken the night before the recording. As far as possible, the QEEG results should represent a drug-free brain.This should not be done without the knowledge and guidance of the prescribing physician.
The usual timeframe to receive feedback after the initial consultation is approximately one week. For further information, please download the EEG info document. The QEEG questionnaire must be completed and brought with to the appointment.
Typical EEG / QEEG electrode placement
For an EEG / QEEG recording, electrodes are placed on the scalp according to the internationally accepted 10-20 placement system.
EEG vs QEEG
Raw EEG looks very different to a QEEG report.
Example of a EEG data:
Example of a QEEG report: