Electroencephalograpy (EEG)

Electroencephalography (EEG) is a diagnostic method to assess the activity of the cerebral cortex during wakefulness and sleep. EEG is used in adults and children. The purpose of EEG is to detect any pathological electrical activity in the brain cells (epileptic discharges). Your physician can refer you to the EEG study if your/your child’s symptoms raise suspicion of epilepsy (for example if you have exerienced seizures, loss of consciousness of unknown etiology etc.) or if the diagnosis of epilepsy has already been confirmed but there is a need for additional information to plan the treatment better. In addition, EEG is used as a supplementary diagnostic method to diagnose other neurological problems and sleep disorders.

Preparation for the study

  • Please wash your hair before coming in for an EEG study. Don’t use any hair care products (hair spray, gel or mousse).
  • Wear comfortable clothes. Make sure there is enough time to arrive, avoid sweating.
  • It is advisable to eat a full meal before the study to avoid hunger during the study. Infants and toddlers can be breast- or bottle-fed during the study.
  • For children it is recommended to bring along a pacifier, a stuffed toy, a blanket or any other aid that helps the child fall asleep.
  • Use any medications that would normally be used every day (that includes medications for epilepsy).
  • The results of the study can be affected by the use of hypnotic drugs, sedatives, antidepressants and alcohol or narcotic substances. Please inform your physician or the medical worker conducting the study about the use of such substances.
  • Inform your physician about previous head injuries, brain operations, meningitis etc., to assure correct interpretation of the study.
  • The mobile phone must be switched off during the study!

Conducting of the study

EEG is painless and safe. Electrodes or a special EEG cap are attached to the previously cleaned scalp. During the study you should lay as relaxed and immobile as possible and are asked to intermittently open and close your eyes. You may also be asked to inhale or exhale deeply during a short period of time and/or are shown short-term bright blinking lights to gather additional information. Deep breathing can cause dizziness and drowsiness. That is normal and will pass within few minutes. Please inform the conductor of the study about any ill-being. The study room is video- and audio-recorded during the study.

Your physician might ask you to refrain from sleep during the night prior to the study or wake up earlier than usual. In case of children, the recommended amount of sleeping hours and the time stayed awake prior to the study depends on the age of the child. Your physician will give you more precise instructions  during the planning of the study.

You/your child may be given a small amount of melatonin to promote falling asleep if needed.

The study lasts about 2 hours that include the application and removal of the electrodes.

The referring physician will give you a review of the study results with further recommendations at a subsequent visit. Your other symptoms, information gathered from the examination and the results of other tests and analyses are taken into account when interpreting the results of the EEG study.

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