An electroencephalography (EEG) system records the electrical activity of the brain and is often used to diagnose several neurological disorders, including epilepsy. There are various EEG systems available; the patient’s symptoms and illness will determine which system to utilize. A routine EEG is one of the more common neurological diagnostic tools used, followed by the ambulatory and video monitoring EEG.
A routine EEG system involves the use of small electrodes attached to a main electrical and computer unit which is responsible for rendering waveforms called traces. Different regions of the brain correspond to a particular trace. In order to capture the waveforms of each trace, electrodes are strategically placed on various areas of the scalp and face, corresponding to a specific region of the brain. While the EEG is being administered, the patient is usually in a dark or dimly lit room lying flat on a comfortable bed or reclining chair.
Sometimes patients are asked to perform several activities in order to increase the likelihood of recording a neurological abnormality. Rapid opening and closing of the eyes and deep breathing are just two possible activities the EEG technologist will instruct the patient to do. The technologist may also shine rapidly flashing lights into the patient’s eyes, further increasing the possibility of a neurological abnormality appearing.
Sleeping during the routine EEG is usually the other part of the test. Doctors may ask patients to abstain from sleep the night before the scheduled EEG is to take place. This is another method to induce abnormal neurological readings, especially in the case of epilepsy. Total test time can vary between 40 minutes to one hour depending on the person taking the test.
In some patients with epilepsy a routine EEG may be inconclusive, necessitating the need for further testing. Routine EEGs only record about 20 to 40 minutes worth of brain activity that might not reflect abnormalities which may arise many hours later. To solve this issue, doctors may order a video EEG or an ambulatory EEG, to provide greater neurofeedback.
The portability of the ambulatory EEG system makes it possible for the patient to undergo normal daily activities while recording any brain abnormalities. Like the routine EEG system, the electrodes are connected to a small portable device usually housed in a shoulder bag, which records the brain’s electrical activity. In contrast, a video EEG system allows for minimal physical activity while remaining in a study room very similar to the routine EEG. Video EEGs are usually done in an inpatient setting to achieve better results.