FATMOP

FATMOP is a mnemonic device used by EEG technologists to remember the characteristics to include in a technical description of an electroencephalogram (EEG).

Frequency: Number of complete cycles of repetitive waves or complexes in 1s. Measured in cycles per second (c/s) or Hertz (Hz).

Amplitude: Is a measure of the change of EEG signals with respect to the mean value, measured in microvolts (µV), and often expressed as the difference between the maximum and minimum deviation (i.e. peak-to-peak), or EEG from baseline-to-peak. EEG amplitude depicts the difference in electrical potential between electrode pairs. Size of the output deflections are dependent upon the method of derivation (i.e. montage), inter-electrode distance, and may be distorted by intervening structures, particularly the skull.

Topography: Spatial distribution of EEG features (rhythm, voltage fields, spectra, evoked potential etc.) over the scalp or cerebral cortex.

Morphology: Refers to the form of EEG waves (i.e. their shape and physical characteristics).

Organization: Degree to which the posterior dominant rhythm (PDR) conforms to certain characteristics displayed by most subjects in the same age group, without personal or family history of neurologic and psychiatric diseases, or other illnesses that might be associated with dysfunction of the brain. The organization of PDR progresses from birth to adulthood.

Period: Duration of a complete cycle of individual graphoelement in a sequence of regularly repeated EEG waves or complexes. The period of the graphoelement of an EEG rhythm is the reciprocal of the frequency of the rhythm.

(For example, the duration of a spike-and-slow-wave complex in 3 c/s spike-and-slow-waves is 1/3 = 0.333).

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