What is an Electroencephalogram? (EEG)An electroencephalogram (EEG) is a diagnostic test that detects electrical activity in the brain using electrodes (small, flat metal discs) attached to the scalp. These electrodes are special sensors with wires attached to a computer. The computer records the brainís electrical activity through wavy lines.
An EEG is a non-invasive procedure usually recommended by neurologists to diagnose neurological and brain diseases. The test is done by an EEG technician at the doctorís office/hospital/lab.
Why is an EEG done?An EEG is primarily used to detect a condition called epilepsy (seizures) in which the brainís normal electrical activity is altered. An EEG can also detect the type of seizure.
EEGs are also used to:
- Check out brain injuries
- Ascertain reasons for unexplained fainting spells or bouts of unconsciousness
- Check out memory disorders like dementia and Alzheimerís
- Ascertain if a comatose person is brain dead
- Check for various tumors and brain cancers
- Diagnose sleep disorders like narcolepsy
- Monitor brain activity in an anesthetized state during brain surgeries
- Diagnose if a personís disease can be attributed to a physiological reason (brain, spinal cord or nervous system) or a psychological reason.
How is an EEG performed?The brain cells or neurons communicate with each other via tiny electrical signals called impulses. The EEG measures these electrical impulses.
The EEG procedure:
- The person is required to lie supine on a bed/reclining chair.
- Electrodes are attached to the scalp with the aid of an EEG electrode paste (which is a conductive gel).
- The electrodes are connected via wires to a recording machine/computer.
- The machine translates the brain impulses into wavy patterns recorded on the computer.
- The person needs to lie still during the procedure with eyes closed. Sometimes the person may be asked to breathe deeply or take quick breaths or focus on an object.