EEG and Ambulatory EEG Monitoring
The electroencephalograph (EEG) is the primary test used to diagnose seizures and epilepsy. The EEG detects and records the electrical activity in the brain through the use of electrodes. Electrodes are small metal discs with thin wires that run to a machine. During an EEG 18 electrodes are pasted to the scalp with special glue that washes out easily. These electrodes are able to detect the electrical activity within the brain and record it on a computer monitor or paper.
The EEG is a painless test. The morning of the test, you should wash your hair using shampoo only, but do not use hair sprays or gels. Your hair should be clean and oil free. The technician will place the electrodes on your scalp and ask you to sit or lie quietly with your eyes closed. The electrical activity of the brain is recorded in this resting state.
Because the EEG lasts only 20 to 40 minutes, it provides only a brief snapshot of your brain’s activity. If the diagnosis of seizures remains in doubt or if your seizures are not well controlled on your medications, your physician may order additional EEG studies. Your physician may order an ambulatory EEG recording where electrodes and a small recording device are worn at home. You are able to continue your usual activities while wearing the ambulatory EEG. This prolonged recording increases the chance that a seizure will be recorded.