EEG is in an instrument which can detect and record the minute electrical signals emanating from the brain using certain number of electrodes (cables) placed at certain predetermined locations on the skin surface on head. These electrodes pick up the brain activity (bio electric signals) magnify (amplify) them many thousand times, and record them in a graphical form on paper. This record (EEG) represents the ongoing electrical activity of the brain and may show abnormal excessive electrical discharges which can produce fits (epileptiform activities).
EEG is a painless procedure and does not involve any electrical stimulation of the patient. The patient has to cooperate and remain relaxed and quietly during the procedure to get a good quality graph. The hair on the head should be dry and free of oil in order to pick up the electrical signals without distortion. It is advised that the patient refrain from applying oil on the head for one or two days before the test, and have a good shampoo bath of the head and dry the hair well on the day of the test. Unless advised otherwise the patient should take the medicines as usual and have the normal meals (should not be fasting) prior to the test. The procedure altogether takes about 30 to 45 minutes.
X Ray films of the head, CT Scan and MRI Scan of the head are useful to study the appearance of the brain and surrounding structures which might be abnormal in a small percentage of patients. They are ordered only when a structural abnormality of the brain is considered to be the cause of the seizure.