What Can Cause an Abnormal EEG?

Any EEG that deviates from the normal range can be described as abnormal. Abnormal EEG only describes a state of brain function. Only in combination with the clinical, compare and observe the clinical signs of patients before and after examination, will it have a clear diagnostic significance.

Abnormal EEG

Right!

Chinese name: Abnormal EEG
Foreign name: EEG

Abnormal: Out of range

Individual differences in electroencephalography (EEG) are greater, especially in children at the developmental stage. Individual differences are even greater. Therefore, there is currently no calculation method that can quantitatively give the normal range of EEG at different ages.

Mild abnormal EEG cannot be diagnosed as epilepsy and only 50% of patients with epilepsy have abnormal EEG

1. The frequency, amplitude, waveform, distribution, symmetry, stability, and responsiveness of the basic rhythm are abnormal.

2. Each frequency band (, , ,

Boundary linear EEG (peripheral state)

The frequency difference of wave of different leads exceeds 2Hz.

The alpha wave amplitude difference on both sides of the cerebral hemisphere exceeds 30% (except the occipital region).

There are more 20-50V waves in the frontal area.

The number of low-amplitude waves in the frontal region is slightly more, but does not exceed 25%.

Mild abnormal EEG

Alpha wave frequency difference exceeds 24.5Hz. The amplitude is asymmetric, with a difference of more than 30% on both sides and a pillow area of more than 50%.

The physiological response is not obvious or asymmetric.

The frequency of wave is slowed down to 8Hz, the amplitude of wave is over 100V and the adjustment is not good. wave increases, the amplitude reaches 50-100V. In the frontal or temporal region, the amplitude wave reaches 20%, and the low amplitude wave reaches 10%. Excessive ventilation induces waves above 70 V or waves above 25 V.

Moderate abnormal EEG

The alpha wave frequency slows down to 7-8Hz, and the original alpha wave in the occipital region disappears or disappears on one side.

Alpha activity with high paroxysmal amplitudes in frontal and temporal regions.

The number of medium wave activities reaches 50%.

A small number of spikes, spikes, spikes or spike-slow integrated waves appear.

Excessive ventilation induces high amplitude delta waves.

Severe abnormal EEG

High amplitude or wave is the main rhythm, wave disappears or only a small amount of 8Hz wave is scattered.

Spontaneous or induced long-range or repeated occurrence of high amplitude spikes, spikes, spikes or spike-slow integrated waves.

High degree of irregularity, explosive suppression, periodic distribution, etc.

persistent extensive flat potential.