How do you know if your EEG is abnormal?

Asked By: Liborio Freijedo | Last Updated: 22nd March, 2020
Category: medical health sleep disorders
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The whole brain shows it in generalized seizures. The other way an EEG can show abnormal results is called non-epileptiform changes. This can be a general change in the way a normal brain wave looks. It may have an abnormal frequency, height or shape.

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Also to know is, what are the possible causes for an abnormal EEG?

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)
  • Drug or alcohol abuse.
  • Head injury.
  • Migraines (in some cases)
  • Seizure disorder (such as epilepsy)

Also, what does a EEG show? An electroencephalogram (EEG) is a noninvasive test that records electrical patterns in your brain. The test is used to help diagnose conditions such as seizures, epilepsy, head injuries, dizziness, headaches, brain tumors and sleeping problems. It can also be used to confirm brain death.

Subsequently, one may also ask, what does a normal EEG look like?

Most waves of 8 Hz and higher frequencies are normal findings in the EEG of an awake adult. The morphology of a wave may resemble specific shapes, such as vertex (V) waves seen over the vertex of the scalp in stage 2 sleep or triphasic waves that occur in the setting of various encephalopathies.

Can an abnormal EEG mean nothing?

An abnormal EEG doesn't automatically mean that you, for example, have epilepsy. The EEGs of babies and young children can often record irregular patterns that don't mean anything, or the irregularities may flag previously diagnosed neurological conditions such as cerebral palsy.

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What happens if EEG is abnormal?

This means that sometimes the EEG is described as 'abnormal' (that is 'not normal' brain activity) but does not 'prove' that the person has epilepsy. Also, many people who do have epilepsy will only have 'abnormal' activity on the EEG if they have a seizure at the time the test is happening.

Can EEG show anxiety?

Unique EEG Signal a Potential Depression, Anxiety Biomarker. Increased communication between the amygdala and hippocampus appear to correlate with symptoms of depression and anxiety, in findings that may have treatment implications, new research suggests.

Can EEG detect mental illness?

Electroencephalography (EEG) is primarily of use in diagnosing epilepsy and other brain diseases (1), but there are other reasons why EEG is also an important diagnostic test in psychiatric practice. Epileptic seizures can also mimic psychiatric disorders or trigger episodes with psychiatric symptoms.

Does epilepsy show up on MRI?

Uses of MRI
Structural imaging is used to look for a potential structural cause of someone's epilepsy, such as a scar on the brain. However, for many people with epilepsy, no structural cause for their epilepsy can be found, and so their MRI results are said to be 'normal'.

What does epileptiform mean?


Adjective. epileptiform (not comparable) Of or pertaining to epilepsy, or resembling epilepsy, particularly in regard to its associated seizures. a grand mal epileptiform seizure.

Why would you have an EEG test?

An electroencephalogram (EEG) is a test used to evaluate the electrical activity in the brain. Brain cells communicate with each other through electrical impulses. An EEG can be used to help detect potential problems associated with this activity. An EEG tracks and records brain wave patterns.

Can EEG show dementia?

An electroencephalogram (EEG) may be done to detect abnormal brain-wave activity. Although the EEG is usually normal in people with mild Alzheimer's disease and many other types of dementia, EEG abnormalities do occur in delirium and Creutzfeldt-Jakob disease, which is a cause of dementia.

Will EEG show previous seizure?

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. The EEG generally records brain waves between seizures, called interictal brain waves. These waves may or may not show evidence of seizure activity.

What do spikes on an EEG mean?

Spikes or sharp waves are terms commonly seen in EEG reports. If these happen only once in a while or at certain times of day, they may not mean anything. If they happen frequently or are found in specific areas of the brain, it could mean there is potentially an area of seizure activity nearby.

What does epilepsy look like on an EEG?


The EEG shows patterns of normal or abnormal brain electrical activity. Certain other patterns indicate a tendency toward seizures. Your doctor may refer to these waves as "epileptiform abnormalities" or "epilepsy waves." They can look like spikes, sharp waves, and spike-and-wave discharges.

What does an absence seizure look like on an EEG?

EEG findings in atypical absence seizures
Atypical absence seizures are characterized by slow spike-and-wave paroxysms, classically 2.5 Hz (see the image below). The onset may be difficult to discern, and postictal EEG slowing may be noted. Slow spike-and-wave discharges (2.5 Hz).

How long does it take to read an EEG?

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.

Who reads EEG?

When the EEG is finished, the results are interpreted by a neurologist (a doctor who specializes in the nervous system). The EEG records the brain waves from various locations in the brain. Each area produces a different brain wave strip for the neurologist to interpret.

Do myoclonic seizures show up EEG?

Ictal EEG : Negative myoclonus is seen in association with the spike of a spike or spike-and-wave discharge on EEG. A myoclonic-atonic seizure is a myoclonic seizure followed by an atonic seizure. Sometimes a series of myoclonic jerks occurs prior to the atonia.

What is temporal slowing?


Temporal slowing just means that the brain waves in that area are slower frequency than would be expected. Sometimes this can occur from seizure activity arising from deeper areas of the brain but by the time it's picked up on EEG, it's just seen as slow waves and not as clear 'epileptiform' or seizure activity.

What are the 5 main frequencies measured by EEG?

Signal frequency: the main frequencies of the human EEG waves are:
  • Delta: has a frequency of 3 Hz or below.
  • Theta: has a frequency of 3.5 to 7.5 Hz and is classified as "slow" activity.
  • Alpha: has a frequency between 7.5 and 13 Hz.
  • Beta: beta activity is "fast" activity.

What is a seizure?

A seizure is a sudden, uncontrolled electrical disturbance in the brain. It can cause changes in your behavior, movements or feelings, and in levels of consciousness. If you have two or more seizures or a tendency to have recurrent seizures, you have epilepsy. There are many types of seizures, which range in severity.