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EEG reading involves the interpretation of wave forms largely
by their frequency and to a lesser extent by the morphology
of the wave or of the wave complex of several waves.
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The difficulty lies, in part, in recognizing artifacts and also
in being able to differentiate normal variants from abnormalities.
The frequencies of the EEG waves run from 0.5 per second to
hundreds/second. The machines however usually show frequencies
of upto 26/second.
Waves are usually defined by their frequency and are divided,
on this basis, into:
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* alpha * beta * theta * delta |  |
frequency and are recognizable by their shape; in other instances
pair or groups of waves have typical appearences. Single waves
that are specially shaped include, for instance spikes or sharp
waves - waves that rise rapidly to a point and fall away equally
dramatically with a base that is small compared to the wave's
amplitude.
Some wave forms can be recognized by their morphology
and these include two main types:
1. Specially shaped waves
2. Specially shaped wave complexes
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Artifacts are disturbances caused by technical defects - usually transitory.
Included are such things as electrode movement, with loss of contact,
muscle activity obscuring the EEG, movements of the head, scratching the
scalp, sweating etcetera.
Some of these wave types will be discussed and illustrated by clicking below.
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MORE DETAIL ON THE ABOVE WAVE TYPES
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There are several waves or patterns of waves which are unusual in
appearance yet are not significant for abnormality or disease. These waves
can be misinterpreted. Amongst the more common ones are mu rhythm,
psychomotor variant, lambda waves, POSTS, spindles, vertex waves and .
K Complexes amongst others
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Some of these wave types will be discussed and illustrated by clicking below.
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MORE DETAIL ON THE ABOVE WAVE TYPES