Intro to EEG – Electroencephalography

What is EEG electroencephalography?

An EEG is a test that detects abnormalities in your brain waves, or in the electrical activity of your brain. During the procedure, electrodes consisting of small metal discs with thin wires are pasted onto your scalp. The electrodes detect tiny electrical charges that result from the activity of your brain cells.

What is EEG introduction?

The electroencephalogram (EEG) is a recording of the electrical activity of the brain from the scalp. The first recordings were made by Hans Berger in 1929 although similar studies had been carried out in animals as early as 1870.

What are the 4 basic EEG patterns?

There are four basic EEG frequency patterns as follows: Beta (14-30 Hz), Alpha (8-13 Hz), Theta (4-7 Hz), and Delta (1-3 Hz). In general, the amplitude of the EEG increases as the frequency decreases. Each of the four EEG frequencies is associated with a different level of arousal of the cerebral cortex.

Where is electroencephalography or EEG normally used?

EEG is most often used to diagnose epilepsy, which causes abnormalities in EEG readings. It is also used to diagnose sleep disorders, depth of anesthesia, coma, encephalopathies, and brain death.

Can EEG detect brain tumor?

EEG can also detect abnormal brain waves after a head injury, stroke, or brain tumor. Other conditions such as dizziness, headache, dementia, and sleeping problems may show abnormal brain patterns. It can also be used to confirm brain death.

How do I read my EEG results?


So if you look at just go to the very left side of this page here. And follow this cursor the alphabets that end with the odd. Number are recording electrical activity from the left side of the brain.

What is EEG PDF?

The electroencephalogram (EEG) is a widely used non-invasive method for monitoring the brain. It is based upon placing metal electrodes on the scalp which measure the small electrical potentials that arise outside of the head due to neuronal action within the brain.

What is the process of EEG?

An EEG, or electroencephalogram, is a test that records the electrical signals of the brain by using small metal discs (called electrodes) that are attached to your scalp. Your brain cells communicate with each other using electrical impulses. They’re always working, even if you’re asleep.

What is the normal EEG frequency range?

Most waves of 8 Hz and higher frequencies are normal findings in the EEG of an awake adult. Waves with a frequency of 7 Hz or less often are classified as abnormal in awake adults, although they normally can be seen in children or in adults who are asleep.

Which is better EEG or MRI?

MRI has a higher spatial resolution than electroencephalography (EEG). MRI with hyperintense lesions on FLAIR and DWI provides information related to brain activity over a longer period of time than a standard EEG where only controversial patterns like lateralized periodic discharges (LPDs) may be recorded.

Where are the neurons that make most of the EEG mainly located?

The Frontal Lobe

The Frontal Lobe



The Frontal lobe is the region where most of your conscious thoughts and decisions are made. Also, frontal cortex contains motor areas where voluntary movements of all of our limbs and eyes are controlled. The frontal lobe contains most of the dopamine-sensitive neurons.

Can an abnormal EEG be wrong?

Yes, EEG can be bad for you. The consequences of being misdiagnosed with epilepsy are obvious and serious [9]. When the diagnosis is based largely on an abnormal EEG, no amount of subsequent normal EEGs will ‘cancel’ the previous abnormal one, and the wrong diagnosis is very difficult to undo.

How accurate is EEG test?

If abnormalities on the routine EEG are found, such as focal spikes and generalized spike waves, the risk of seizure recurrence increases two times. However, the routine EEG has its limitations as its accuracy to detect abnormalities after a FSUS has a sensitivity of 17% and specificity of 95% (7).

Can an EEG be misread?

The consequences of misreading EEGs are many. First, it may delay arriving at the correct diagnosis. Once a patient is ‘labeled’ with a diagnosis, it is difficult to undo it. It requires obtaining the original EEG and reinterpreting it.

Can you have an abnormal EEG without having epilepsy?

Furthermore, about 2% of normal school-age children who do not have seizures have epileptic activity on EEG. Conversely, a normal EEG does not exclude epilepsy. Many types of epilepsy may be associated with a normal EEG between seizures. A normal EEG during a “seizure” usually excludes epilepsy as the cause.

Can an EEG detect a previous seizure?

An EEG can usually show if you are having a seizure at the time of the test, but it can’t show what happens to your brain at any other time. So even though your test results might not show any unusual activity it does not rule out having epilepsy.

Can an EEG show brain damage?

An EEG can determine changes in brain activity that might be useful in diagnosing brain disorders, especially epilepsy or another seizure disorder. An EEG might also be helpful for diagnosing or treating the following disorders: Brain tumor. Brain damage from head injury.

Does an abnormal EEG always mean epilepsy?

A normal EEG does not mean that you did not have a seizure. Approximately one-half of all EEGs done for patients with seizures are interpreted as normal. Even someone who has seizures every week can have a normal EEG test. This is because the EEG only shows brain activity during the time of the test.

What makes an EEG abnormal?

Abnormal results on an EEG test may be due to: Abnormal bleeding (hemorrhage) An abnormal structure in the brain (such as a brain tumor) Tissue death due to a blockage in blood flow (cerebral infarction)

Can anxiety cause abnormal EEG?

Background. Since the 1980s, a high EEG abnormality rate has been reported for patients with panic disorder.

What type of seizure is status epilepticus?

A seizure that lasts longer than 5 minutes, or having more than 1 seizure within a 5 minutes period, without returning to a normal level of consciousness between episodes is called status epilepticus. This is a medical emergency that may lead to permanent brain damage or death.

What is Norse disease?

New-onset refractory status epilepticus (NORSE) is defined as a condition, not a specific diagnosis, with new onset of refractory status epilepticus without a clear acute or active structural, toxic or metabolic cause in a patient without active epilepsy.

What triggers status epilepticus?

Imbalance of substances in the blood, such as low blood sugar. Drinking too much alcohol or having alcohol withdrawal after previous heavy alcohol use. Withdrawal from medicines to treat seizures.

How is status epilepticus diagnosed?

Diagnosis. Status epilepticus can be diagnosed by clinical observation, but most often an electroencephalogram (EEG), brain imaging, or lumbar puncture is needed to verify the diagnosis.

How common is status epilepticus?

At some point in their lives, 15 percent of people with epilepsy will experience an episode of status epilepticus. The most common precipitating factor in these cases in adults is withdrawal from medication or noncompliance with the regimen. There may, however, be no obvious cause for the episode.

Can you have status epilepticus without epilepsy?

Status epilepticus can happen with any type of seizure. Status epilepticus can happen in people who have been diagnosed with epilepsy, but also in people who have never had a seizure before. For example, it can happen because of a stroke or head injury, or because of drug or alcohol abuse.