Electroencephalography (EEG) is based on the principle of recording fluctuations in the electrical activity of a broad group of neurons in the brain. The interpretation of the potentials recorded from the scalp by specialists is crucial.
Routine EEG is the most important test for patients presenting with altered consciousness and seizures. It is invaluable in diagnosing epilepsy, classifying patients with confirmed epilepsy, selecting appropriate treatments, determining prognosis, and monitoring the course of the disease. Additionally, EEG is valuable in diagnosing and monitoring all other brain disorders. It provides critical clues in diagnosing and following up specific conditions, such as slow virus diseases, herpes simplex encephalitis, and hepatic encephalopathy. EEG is also used in the evaluation of sleep and sleep disorders.
EEG Procedure
EEG recording typically takes place in a quiet, comfortable environment and lasts at least 30-40 minutes for a routine EEG. Proper placement of electrodes is a crucial preparatory step. The electrodes are attached using appropriate materials, and conductivity is ensured with special pastes or saline solutions. It is essential that the patient's hair is clean before the EEG. Since certain changes can occur during fasting, the patient should not be hungry during the recording. During the EEG, the patient should remain calm, either sitting or lying down, and follow the EEG technician's instructions to open and close their eyes.
During every routine EEG, deep breathing (hyperventilation) is performed to activate an epileptic focus. Intermittent photic stimulation (IFS) is another vital activation method that must be applied in every routine EEG. Sleep studies may be requested at the physician's discretion and provide valuable additional information, especially in children.
Interpretation of EEG Results
To evaluate EEG findings, it is essential to have a thorough understanding of normal EEG characteristics. In every EEG recording, the basic activity is assessed first. Normal baseline activity varies significantly with age, wakefulness, and physiological conditions such as hunger. For example, activity considered normal for a three-month-old baby may be pathological for a three-year-old child. Similarly, the EEG activity of an adult in deep sleep may be a serious pathological finding if observed while awake.
EEG symmetry between the brain hemispheres is important, so comparing the two hemispheres is crucial. Any medications the patient is taking and any metabolic issues should be recorded during the EEG, as certain drugs and metabolic conditions can significantly affect EEG results.
Expertise in EEG Reporting
EEG reports should be prepared by experienced neurologists, with consultation from clinical neurophysiologists when necessary.
At our Lape Hospital, EEG recordings are interpreted by Dr. Ferda Korkmaz Özkanoğlu, a specialist, and consultant Clinical Neurophysiology subspecialist, Prof. Dr. Betül Baykan.
