Fisch EEG Primer Chapter 9 Flashcards
Descriptors of EEG activity (28 cards)
What descriptors can be used to describe and analyze EEG activity? (9)
1) morphology
2) repetition
3) frequency
4) amplitude
5) distribution
6) phase relation
7) timing
8) persistence
9) reactivity
What are some synonyms for waveform?
Waveform morphology or configuration
A rythmic run of waveforms of similar shape are called…
regular or monomorphic
What are some terms that describe the waveform?
sinusoidal, arch-shaped (wicket shaped), saw toothed (asymmetrical triangular shaped), irregular (constantly changing shape)
Monophasic, Diphasic, and Triphasic waves differ in what way?
Differ in the number of wave components on different sides of the baseline e.g. dipasic components on opposite sides of baseline
Epileptiform is a term reserved for describing what type of activity
EEG patterns that are identical to, or specifically associated with, seizure or epilepsy
What is the accepted duration of a spike waveform?
20-70ms
What is the accepted duration of a sharp waveform?
70-200ms
The duration of a sharp or spike wave is related to
size of anatomical area involved AND synchrony of participating neuronal population - longer duration = less synchronous
spike and wave complexes at rates less than 3Hz are called
SLOW spike-and-wave complexes
multiple spikes followed by a slow wave are referred to as
polyspike-and-wave
spike and sharp waves that last less than a few seconds is referred to as
interictal epileptiform activity - its the evolution of this pattern in terms of amplitude and frequency that is referred to as an electrographic seizure patter (ictal pattern)
What is the appearance of a paroxysmal discharge?
begins abruptly, stands out from background, and then disappears suddenly - may be normal or abnormal
Repetition of waves can be described by the following terms…
Rythmic (monomorphic), semirythmic, or irregular
The frequency of EEG activity is commonly divided into 4 groups (beta, alpha, theta, delta). What are the frequencies associated with each?
- beta: >13Hz
- alpha: 8-13Hz
- theta: 4-8Hz
- delta: <4Hz
What is the smallest division of reported frequency in EEG?
0.5Hz
Amplitude should be described in terms of…
microV (NOT mm since the calibration settings may vary)
Amplitude is often described in loose terms such as (low, medium, high)
-low 50microV
NOTE: it is important to report the type of montage used when describing amplitude since montage adjustments will alter recorded amplitude.
Even slight asymmetries in amplitude of recorded EEGs may be significant with the exception of…
alpha rythym and POSTs which can be up to %%% different
Distribution can be described by the following terms…(3)
- widespread, diffuse, generalized
- lateralized (sometimes shifting lateralization such as vertex waves or sleep spindles)
- focal or localized
What is the term used to describe three or more anatomically distinct area generating epileptiform spikes and waves?
Mutifocal epileptiform pattern
In describing focal activity in the description portion of an EEG it is important to specifiy..
electrode names where abnormality is identified and NOT the head region
Phase of a wave refers to the overall alignment of…
peaks/troughs and may be described by a ‘phase angle’
What are the terms used to describe activity occurring at the same time?
Simultaneous or synchronous - simultaneous activity is presumed to originate from volume conduction to surrounding tissues
NOTE: even small timing differences are likely the result of transsynaptic transmission
