Fisch EEG Primer Chapter 11 Flashcards

The normal EEG of wakeful resting adults of 20-60 years of age

1
Q

This type of rythym consists of sinusoidal waveforms >8H and <13Hz maximal over the posterior head region and is typically blocked by eye opening and disappears during drowsiness and sleep

A

The alpha rythym

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

This rythym consists of waves >13Hz in either a wide distribution or limited to frontal or posterior head regions; should disappear during later stages of sleep; typically of lower amplitude than alpha

A

The beta rythym which is almost always a GOOD prognistic sign (requires normal cortical function) - can be caused by benzos/barbs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Mu rythym (can be precipitated by scanning visual images) consists of…

A

seen in less than 5% of EEGs, arch-shaped 7-11 Hz of trains over central to central parietal regions typically in younger adults.; best seen on bipolar montage when alpha is blocked by eye opening
NOTE:previously known at ‘wicket’, ‘comb’, or ‘arceau’ rythym

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Lambda waves (can be precipitated by looking at images containing a lot of detail) consist of…(morphology, duration, phase, amplitude

A
  • sawtooth shaped and positive polarity occurring primarily in occipital regions - look like POSTs
  • 100-250 ms
  • typically diphasic
  • 50microV
  • marked asymmetry is abnormal to lower amplitude side
  • may be a physiologic VEP since waveform, delay, etc. same pattern
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Vertex sharp transients (V waves) consist of…

A

sharp transients of negative polarity at the vertex -commonly seen in sleep
NOTE: may be seen in awake adults/children after startle response

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Kappa rythym consists of…

A

bursts of very low amplitude waves of alpha or theta frequency seen in temporal region that are seen in subjects engaged in mental activity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Intermittent posterior theta rythyms…

A

are more rare than alpha or beta rythyms;

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

low voltage activity can sometimes be modified through the following activating procedures

A

hyperventilation, photic stimulation and sleep - low voltage EEG is considered abnormal if altered from baseline

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Alpha rythym that never exceeds 8 Hz is…

A

always abnormal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Alpha rythym may decrease by approximately 1 Hz during…

A

drowsiness
NOTE: alpha rythym should be a constant value throghout life (same on serial recordings), decreases of 1Hz or more during adult life if abnormal even if the absolute value is still within the normal range.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is the phenomena of alpha rythym temporarily increasing by 1 Hz during eye closure and then rapidly returing to baseline

A

squeak phenomena

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the accepted range of frequency difference between the hemispheres

A

SHOULD BE THE SAME FREQUENCY, even slight difference if difference is persistent considered definitely abnormal (lower frequency hemisphere is abnormal)
NOTE: alpha frequencies do not need to be in phase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Alpha frequency activity in the Fp1 and Fp2 regions..

A

is artifact until proven otherwise

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Asymmetric alpha amplitude typically follows this pattern…

A

right alpha rythym is typically of higher amplitude, left alpha rythym should be at least 50% of that on right. - may be caused by different thickness of occipital bones
NOTE: occasoinally higher amplitude is seen on the left

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is Bancaud’s phenomena?

A

Unilateral blocking of the alpha rythym

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are some reasons to test eye opening as an activating procedure?

A

1) reactivity and symmetry of alpha blocking
2) demenostrate artifacts produced
3) bring out rythyms hidden by alpha (e.g. Mu rythym
4) test other EEG reactivity
5) precipitate abnormal reaction to eye opening

17
Q

Describe a slow alpha variant

A

rythyms 3.5 - 6.5 Hz (half the frequency of normal apha) appearing in same records at different times with normal alpha rythym

18
Q

What are some maneuvers used to block frontal beta rythym?

A

blocked by movement, intention to move, and tactile stimulation. Effect often greatest when the contralateral extremity is moved.

19
Q

What are some maneuvers used to block widespread beta rythym?

A

not blocked by any stimulus

20
Q

What is another name for posterior beta rythym?

A

Fast alpha variant; beta frequency rythym usually (16-20Hz) that intermixes or alternates with alpha rythym and is blocked by same alpha blocking maneuvers

21
Q

beta rythym amplitude asymmetry between hemispheres is considered normal if homologous head regions vary by no more than…

A

35% - in the absence of a skull defect (causes breach artifact), the lower amplitude is abnormal

22
Q

What are some maneuvers used to block Mu rythym?

A

blocked by movement, intention to move, and tactile stimulation. Effect often greatest when the contralateral extremity is moved.

23
Q

When is Mu rythym considered abnormal?

A

frequent unilateral trains, amplitude asymmetry - abnromal on side of lower amplitude or frequency