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Electroencephalography (EEG)

An electroencephalography (EEG) evaluates brain wave activity and determines whether there are any abnormalities. The procedure can be used to help diagnose epilepsy and other brain disorders.

Multiple small, metal electrodes are placed along the scalp during a routine procedure, which typically lasts up to an hour. There is an extensive preparation period before the test begins, however, that includes cleaning the scalp, using a salty gel to mount the electrodes, and then establishing a baseline of neural activity without stimulation. Ambulatory EEGs, in-home video EEGs, or hospital-based EEGs might also be ordered when longer study periods are needed.

The procedure maps electrical charges from brain activity as patients are asked to perform certain activities or observe specific stimuli. Charges are recorded, amplified, and graphed. Results usually appear as a series of wavy lines with peaks and valleys that a UTHealth Neurosciences neurologist will analyze and interpret. Interictal EEG recordings are obtained between seizures, while ictal EEG activity describes abnormalities during a seizure. It is rare for an EEG to capture seizure activity.

Stereoelectroencephalography (SEEG), which is a surgical procedure, might be needed to help identify the area of the brain where seizures originate in patients with epilepsy. The procedure involves placing electrodes within specific areas of the brain and allows for monitoring periods of up to four weeks. Our Texas Comprehensive Epilepsy Program has an expert team to perform this procedure, as well as to develop comprehensive treatment plans for patient with epilepsy.

EEGs can also be used to help diagnose sleep disorders, encephalitis, dementia, memory problems, brain damage, brain death, tumors, or strokes. Because the test has somewhat limited spatial resolution, it might be followed up with higher-resolution imaging, such as a CT or MRI scan. An EEG might also be used to monitor activity during brain surgery. EEGs are widely considered safe and painless procedures. Prepare for your procedure by following your doctor’s orders, which might include avoiding hair products and caffeine.

Tests and Treatments


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At UTHealth Neurosciences, we offer patients access to specialized neurological care at clinics across the greater Houston area. To ask us a question, schedule an appointment, or learn more about us, please call (713) 486-8000, or click below to send us a message. In the event of an emergency, call 911 or go to the nearest Emergency Room.


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