Fisch EEG Primer Chapter 9

Question 1

What descriptors can be used to describe and analyze EEG activity? (9)

Answer 1

1) morphology
2) repetition
3) frequency
4) amplitude
5) distribution
6) phase relation
7) timing
8) persistence
9) reactivity

Question 2

What are some synonyms for waveform?

Answer 2

Waveform morphology or configuration

Question 3

A rythmic run of waveforms of similar shape are called…

Answer 3

regular or monomorphic

Question 4

What are some terms that describe the waveform?

Answer 4

sinusoidal, arch-shaped (wicket shaped), saw toothed (asymmetrical triangular shaped), irregular (constantly changing shape)

Question 5

Monophasic, Diphasic, and Triphasic waves differ in what way?

Answer 5

Differ in the number of wave components on different sides of the baseline e.g. dipasic components on opposite sides of baseline

Question 6

Epileptiform is a term reserved for describing what type of activity

Answer 6

EEG patterns that are identical to, or specifically associated with, seizure or epilepsy

Question 7

What is the accepted duration of a spike waveform?

Answer 7

20-70ms

Question 8

What is the accepted duration of a sharp waveform?

Answer 8

70-200ms

Question 9

The duration of a sharp or spike wave is related to

Answer 9

size of anatomical area involved AND synchrony of participating neuronal population - longer duration = less synchronous

Question 10

spike and wave complexes at rates less than 3Hz are called

Answer 10

SLOW spike-and-wave complexes

Question 11

multiple spikes followed by a slow wave are referred to as

Answer 11

polyspike-and-wave

Question 12

spike and sharp waves that last less than a few seconds is referred to as

Answer 12

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)

Question 13

What is the appearance of a paroxysmal discharge?

Answer 13

begins abruptly, stands out from background, and then disappears suddenly - may be normal or abnormal

Question 14

Repetition of waves can be described by the following terms…

Answer 14

Rythmic (monomorphic), semirythmic, or irregular

Question 15

The frequency of EEG activity is commonly divided into 4 groups (beta, alpha, theta, delta). What are the frequencies associated with each?

Answer 15

• beta: >13Hz
• alpha: 8-13Hz
• theta: 4-8Hz
• delta: <4Hz

Question 16

What is the smallest division of reported frequency in EEG?

Answer 16

0.5Hz

Question 17

Amplitude should be described in terms of…

Answer 17

microV (NOT mm since the calibration settings may vary)

Question 18

Amplitude is often described in loose terms such as (low, medium, high)

Answer 18

-low 50microV
NOTE: it is important to report the type of montage used when describing amplitude since montage adjustments will alter recorded amplitude.

Question 19

Even slight asymmetries in amplitude of recorded EEGs may be significant with the exception of…

Answer 19

alpha rythym and POSTs which can be up to %%% different

Question 20

Distribution can be described by the following terms…(3)

Answer 20

• widespread, diffuse, generalized
• lateralized (sometimes shifting lateralization such as vertex waves or sleep spindles)
• focal or localized

Question 21

What is the term used to describe three or more anatomically distinct area generating epileptiform spikes and waves?

Answer 21

Mutifocal epileptiform pattern

Question 22

In describing focal activity in the description portion of an EEG it is important to specifiy..

Answer 22

electrode names where abnormality is identified and NOT the head region

Question 23

Phase of a wave refers to the overall alignment of…

Answer 23

peaks/troughs and may be described by a ‘phase angle’

Question 24

What are the terms used to describe activity occurring at the same time?

Answer 24

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

Question 25

What is the term sometimes used to describe the persistence of waves which describes the portion of time these waveforms appear?

Answer 25

index e.g. delta index of 20 indicates that delta activity was present 20% of the time

Question 26

What is the delta index associated with stage 3 sleep?

Answer 26

20-50% of an epoch (30 sec) contains 2Hz or slower waveforms of greater than 75microV in leads C3 to A2

Question 27

What is the delta index associated with stage 4 sleep?

Answer 27

> 50% of an epoch (30 sec) contains 2Hz or slower waveforms of greater than 75microV in leads C3 to A2

Question 28

A poor clinical outcome is typically associated with an absence of EEG reactivity except in the cases of…

Answer 28

• general anesthesia
• hypothermia
• hypotension
• invariant pattern (lacking spontaneous variability)