An EEG stands for an Electroencephalogram. Difficult to pronounce and still not considered particularly valuable for the diagnosis of headaches, except for distinguishing complicated migraines from complex partial seizures. It can be used to find out if there is actually some kind of a malfunction in the brain.
An EEG measures the electrical signals of the brain by using a set of electrodes placed on the scalp. These signals are then transmitted to a machine called the polygraph which records these signals.
It is important that any medications that you are taking prior to an EEG should be discussed with your doctor. Also since, the electrodes will be placed on the head, it is essential to wash your hair a day prior to the test. And then do not use any hair cream, spray or oil.
During the test, about 20 electrodes are placed on the scalp. Anti-convulsant medications can be started soon after the EEG is over. Though the EEG does not pinpoint the exact problem in adults, it can, however, be used to find out cerebral abnormalities in children.
You have to understand that in order to treat the problem of headache completely you have to make sure that you take all the steps to diagnose it properly and EEG works as a major step in the same process.