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Dr. Andrew Rynne
Dr. Andrew Rynne

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Article Home Adult and Senior Health EEG and other tests in epilepsy

EEG and other tests in epilepsy

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EEG records patient?s brain wave activity, in epilepsy the electrical activity of brain is disturbed. The pattern of brain wave activity may help in diagnosing seizure type.


Diagnostic tests in epilepsy

  • EEG
  • MRI brain
  • CT brain- plain and contrast
  • Positron emission tomography- PET
  • X-ray skull
  • Complete blood test  

Electroencephalogram- EEG

Normal EEG characters

  • In adults who are awake, the EEG shows mostly alpha waves and beta waves.
  • The two sides of the brain show similar patterns of electrical activity.
  • There are no abnormal bursts of electrical activity and no slow brain waves on the EEG tracing.
  • If flashing lights are used during the test, one area of the brain (the occipital region) may have a brief response after each flash of light, but the brain waves are normal.

Abnormal EEG pattern

Infantile spasms

Hypsarrhythmia- consists of diffuse giant waves (high voltage, >400 microvolt’s) with a chaotic background of irregular, multifocal spikes and sharp waves and very little synchrony between the cerebral hemispheres.

Lennox- gastaut syndrome

The slow spike and wave activity serves- poor prognosis

Fast spike and wave (>2.5 Hz) activity, which carries a dramatically better prognosis

Absence seizure

3-Hz generalized spike and wave discharges

Juvenile myoclonic epilepsy

Polyspike and wave discharges by definition have at least 3 spikelike components. Polyspike and wave response produced by photic stimulation.

Benign partial/rolandic epilepsy

Associated with typical centrotemporal spikes



Video EEG

Video EEG records seizures on videotape and on computer so that the doctor can see what happens in preictal phase (just before), ictal phase (during), and post ictal phase (right after a seizure).

This test can be very helpful in finding the specific area of the brain that the seizures may be coming from.

Ambulatory EEG monitoring

In ambulatory EEG monitoring, the person is able to move around, and the test allows for long periods of time in recording of electrical activity in the brain.

MRI / CT brain

MRI has greatly enhanced the ability to detect certain lesions in the brain that cause seizures. (Lesion is defined as any diseased tissue.)

MRI is important in diagnosing the causes of epilepsy, and in evaluating potential candidates for surgery.