Quantitative Electroencephalogram The EEG or Electroencephalogram, is produced by cells in the outer edge of the brain called the cortex (literally the “bark” of the brain, the outer rind) which oscillate in large groups, producing a summed wave or set of waves. These waves are recorded and separated into different types by Fourier Transformation. The pictures above illustrate the major method of actually recording these waves using an Electrocap (tm) which stretches to fit the size of the person’s head. Small cups are filled with nontoxic electrode gel and a clean trace is usually made. When many sites of the brain EEG are sampled at the same time there are several advantages. First we can draw a more comprehensive picture of what the entire brain is doing. Second, all the activity is taking place at the same time and time resolution is very fine. In this way EEG recordings offer better time resolution the other methods of evaluating brain function like MRI or PET scans. Once a recording is made we work to remove artifacts. These are produces by a wide variety of outside events like head movement, eye blinks, loss of good electrode contact, sweat, wiring problems. But there are also internal events: primarily drowsiness, medication interactions, muscle artifact, heartbeat artifact, tongue movements and so on. All of these can be mistaken for brain activity and thus bias the EEG. Software allows us to scan the record and remove anything that appears not to be cortical and we therefore can have more confidence that we are measuring the brain and not the eyelid. But this process is as much an art as a science and we do not have unequivocal ways of removing the chaff from the wheat! When the recording has been artifacted it is compared to a database of normal brains. There are several standardized databases, which are currently in use. They all consist of large numbers of records, which were made from people not suffering from medical or psychiatric problems. These recordings are used to differentiate normal EEG patterns from abnormal ones. They are often displayed as colored topographic maps, which show what is high, and what is low using colors. While attractive, these displays are only as good as the underlying data. When I perform a QEEG I try to ensure that the person has had a good night’s sleep, that all possible medications have been held temporarily, that the hair is washed several times. I also only perform them in the morning hours to ensure wakefulness (no guarantee for some people). Some practical details: • It takes approximately 90 minutes of the client’s time. • Unfortunately, insurance will not over this type of evaluation and I must charge my going rate of $300. If a formal reading by a neurologist is needed there will be additional charges. • I usually provide a written report which can be sent to an attending physician Here is an example of how we use the QEEG in clinical practice: ADD/ADHD http://en.wikipedia.org/wiki/ElectroencephalographyUsing%20a%20QEEG.htmlshapeimage_1_link_0shapeimage_1_link_1
What is QEEG?