electroencephalogram
Meaning of electroencephalogram: The recording is often obtained under specific conditions, such as during sleep or with flashing lights, to help capture patterns not seen at rest.
Definition of electroencephalogram
An electroencephalogram, abbreviated EEG, is a test that records the electrical activity produced by nerve cells within the brain. It is performed by attaching a series of small electrodes to the scalp, each connected to equipment that detects and displays the pattern of electrical signals occurring across different areas of the brain over time.
An EEG can be recorded over a brief period in a clinical setting or, in some cases, continuously over a longer period, and certain conditions, such as sleep deprivation or specific visual stimulation, are sometimes used during the test to help bring out abnormal electrical patterns that might not otherwise appear.
An EEG is used primarily to evaluate seizures and other disorders involving abnormal electrical activity within the brain, and it can also provide information relevant to certain sleep disorders and to assessing brain activity in someone who is unconscious or under anesthesia.
Also known as
Used in a sentence
An EEG was ordered to evaluate the patient's recurrent episodes of altered awareness.
Good to know
An EEG recorded between seizures can appear normal even in someone with a well established seizure disorder, since abnormal electrical activity is not necessarily present at every moment the test is performed.
Word origin
Where “electroencephalogram” comes from
Formed from Greek elektron, meaning amber, the substance in which static electricity was first studied, and enkephalos, meaning brain, combined with gramma, meaning something written or recorded.