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An electroencephalogram (EEG) is a test used for measuring and recording brain waves. Special sensors called electrodes are attached to your head. They're hooked by wires to a computer. The computer records your brain's electrical activity on the screen. Or it may record the activity on paper as wavy lines. Changes from the normal pattern of electrical activity can show certain conditions, such as seizures.
Four major brain waves exist: α has a frequency that ranges from 8 to 14 cycles per second (cps) and is found in the occipital part of the brain. Beta covers 14 to 30 cps. Δ wave includes frequencies that are below 5 cps. Theta wave covers the range between 5 and 8 cps. A waves are more active during relaxation and light sleep. Nonetheless, their function is altered by deep mental activities. Beta waves, on the other hand, appear during mental concentrating periods.
Why It Is Done
An EEG may be done to:
· Check for epilepsy and see what type of seizures are occurring. EEG is the most useful and important test for checking if someone has epilepsy.
· Check for problems with loss of consciousness or dementia
· Help find out a person's chance of getting better after a change in consciousness.
· Find out if a person who is in a coma is brain-dead.
· Study sleep disorders, such as narcolepsy.
· Watch brain activity while a person is getting general anesthesia for brain surgery
· Help find out if a person has a physical problem or a mental health problem. Physical problems include problems in the brain, spinal cord, or nervous system.
Disponível em: <http://www.webmd.com/epilepsy/electroencephalogram-eeg-21508%1>. Acesso em 21 mar. 2017. (Adaptado)
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