Quantitative EEG (QEEG) Assessment (Brain Mapping)

Quantitative EEG (QEEG) Assessment (Brain Mapping)

Quantitative EEG involves the digital assessment of the EEG signal. However, prior to assessing the results of digital information derived from the recording, it is important to visually inspect the EEG tracing to determine whether the recording was performed correctly, to eliminate artifact and to assess the need for a physician referral. Additionally, a great deal of useful information can be derived from examining the EEG tracings, which are collected under a variety of conditions.

The analog EEG tracings are derived from 19 sensors placed on the scalp plus an additional pair of sensors placed on the ears as a reference. Commonly this is done using an electrode cap with sensors embedded in a stretchy mesh. The resulting information is then digitized by the EEG amplifier and processed by sophisticated software. The resulting numerical values provide a wealth of information which can be utilized in a variety of ways. One of the most important tools developed from this digitized information has been the quantitative EEG or QEEG normative database. A normative database is the result of many years of development from an initial sample of nearly seven hundred typical individuals from a variety of age groups. EEG recordings from these typical individuals are then processed and subjected to statistical analysis and the results are then available for comparison.

Measures that can be utilized for comparison include the actual voltage of the electrical activity at each location and in various EEG frequency bands. Additionally the relationship between areas can be explored through a variety of techniques including coherence, phase, asymmetry and other metrics that describe cortical relationships. Thus, communication associated with complex neural pathways can be explored and areas that demonstrate deficient communication characteristics can be highlighted for training.

This approach to "brain mapping" is in many ways superior to other methods of neural imaging. The EEG has a very fast response time, measured in milliseconds, whereas other forms of imaging require several minutes to assess functional changes. This faster time constant allows the EEG to visualize real-time activity, to assess response characteristics, which occur in less than a tenth of a second, as those responses progress through different areas of the brain and to identify communication characteristics that are invisible to other imaging techniques. Finally, brain mapping using quantitative EEG can be used to guide neuro-training to facilitate the optimum intervention for each individual client.

Quantitative EEG assessment services are available for individuals and include the EEG recording, database comparison and a comprehensive written report. The service is also available for professional practitioners who provide their own EEG recording and therefore only include the database comparison and written report. Databases utilized include NeuroGuide from Applied Neuroscience Incorporated, the database developed by the Human Brain Institute in St. Petersburg Russia and LORETA developed by the key Institute in Zürich Switzerland.

The equipment used at the Minnesota Neuro-Training Institute is the state-of-the-art Nexus-32/BioTrace system developed by Mind Media in the Netherlands. The system utilizes 24-bit DC coupled amplifiers, shielded input cables and the most sophisticated digital processing software currently available.