What does a normal EEG mean?
The electroencephalogram (EEG) is the depiction of the electrical activity occurring at the surface of the brain. Frequency (Hertz, Hz) is a key characteristic used to define normal or abnormal EEG rhythms. Most waves of 8 Hz and higher frequencies are normal findings in the EEG of an awake adult.
EEG: If performed within 24-48 hours of a first seizure, EEG shows substantial abnormalities in about 70% of cases. The yield may be lower with longer delays after the seizure. If the standard EEG is negative, sleep-deprived EEG will detect epileptiform discharges in an additional 13-31% of cases.
- Foods which may cause energy peaks and slumps include: white bread; non-wholegrain cereals; biscuits and cakes; honey; high-sugar drinks and foods; fruit juices; chips; mashed potatoes; parsnips; dates and watermelon. In general, processed or overcooked foods and over-ripe fruits.
- In almost half (49%) of all seizures in older adults, the cause is unknown. The majority of the known causes of seizure are stroke, neurodegenerative diseases such as Alzheimer's disease, trauma, tumors, metabolic disorders such as uremia, hyperglycemia, hypoglycemia, hyponatremia, alcohol withdrawal, or infection.
- When this happens to someone with epilepsy it may be called Sudden Unexpected Death in Epilepsy (or SUDEP). SUDEP is when a person with epilepsy dies suddenly and where no other cause of death is found. It may be that they died during or after a seizure. In the UK around 600 people die from SUDEP each year.
Epileptiform transients such as spikes and sharp waves are the interictal marker of a patient with epilepsy and are the EEG signature of a seizure focus. Nonepileptiform abnormalities are characterized by alterations in normal rhythms or by the appearance of abnormal ones.
- Localized brain dysfunction is caused by disorders that occur in a specific area of the brain, including the following: Brain tumors and abscesses. Disorders that reduce blood flow (and thus the oxygen supply) to a specific area, such as a stroke.
- The measurements given by an EEG are used to confirm or rule out various conditions, including:
- seizure disorders (such as epilepsy)
- head injury.
- encephalitis (inflammation of the brain)
- brain tumor.
- encephalopathy (disease that causes brain dysfunction)
- memory problems.
- sleep disorders.
- The International Federation of Societies for Electroencephalography and Clinical Neurophysiology (IFSECN) describes interictal discharges as a subcategory of "epileptiform pattern," in turn defined as "distinctive waves or complexes, distinguished from background activity, and resembling those recorded in a proportion
An electroencephalogram (EEG) is a test used to evaluate the electrical activity in the brain. An EEG can be used to help detect potential problems associated with this activity. An EEG tracks and records brain wave patterns. Small flat metal discs called electrodes are attached to the scalp with wires.
- The test itself will take about 30-60 minutes. Placing the electrodes usually takes 20 minutes, but can take up to an hour, so the entire procedure may take about one to 2 hours. If you have an ambulatory EEG, brain activity is recorded for 24 hours or more.
- An EEG, or electroencephalogram, is a test that can help diagnose epilepsy. During an EEG, the electrical signals of the brain are recorded. This electrical activity is detected by electrodes, or sensors, placed on the patient's scalp and transmitted to a polygraph that records the activity.
- An electroencephalogram (EEG) is a recording of the electrical waves of activity that occur in the brain, and across its surface. Electrodes are placed on different areas of a person's scalp, filled with a conductive gel, and then plugged into a recording device.
Updated: 16th October 2019