Normal brain function involves continuous electrical activity of neurons. An EEG can record some of this activity. Electrodes are placed on the scalp. The electrodes are connected to apparatus that measures electrical potential differences. They record patterns, also known as brain waves. They focus on the activity of the cortex rather than activity of the white matter of the brain. Each of us have a different brain wave pattern. You could imagine this as a fingerprint of the brain. There are four different classifications of waves;
- Alpha Waves
- Beta Waves
- Theta Waves
- Delta Waves
Brain waves change with age, sensory stimulation, brain disease an the chemical state of the body. EEG’s are used for research on sleep and for diagnosis of epilepsy and many types of brain lesions. If the brain waves are too fast or too slow it is noted that the cortical cerebral function may be interfered with. EEG can also help in the diagnoses of traumatic brain injury. They use a scale to determine the severity of brain injury from mild to severe. Brain waves are always present even during unconsciousness or coma. If they are not present it is consider a flat EEG and brain death.
EEG is a real time test so its diagnostic value is weak, especially when looking for subtle seizure activity.
- is only sensitive to brain abnormalities which occur while it is being administered.
- is rarely positive in MTBI or concussion cases.
- is intended to be diagnostically sensitive for seizures. Yet because it only give a report of what happened while “under the hood,” so to speak, it misses most seizure activity.
- is also a very outdated technology. We continue to hope for a breakthrough development where the capacity of something like a smart phone, would be dedicated to a portable EEG device