MODULE V - POLARITY AND MONTAGES

Question 1

What is an EEG montage?

Answer 1

It is a layout of electrode positions on the scalp that is amplified and used to record electrical activity in the brain

Question 2

What are the two main types of montages

Answer 2

Longitudinal Bipolar and referential

Question 3

What type of brain activity are bipolar montages useful for?

Answer 3

For identifying focal and generalized brain activity

Question 4

Name three types of bipolar montages?

Answer 4

Double banana; transverse, hat (or circumferential)

Question 5

Name three types of referential montages?

Answer 5

Referential average, ipsilateral, contrateral

Question 6

What is a double banana montage?

Answer 6

It is a longitudinal bipolar montage that records activity from electrodes placed on the left and right hemispheres of the brain. It is useful for identifying focal and generalized brain activity

Question 7

What is a transverse montage?

Answer 7

It is a bipolar montage loosely referred to as the sleep montage that highlights activity from the central electrodes that highlight sleep

Question 8

What is a hat (circumferential) montage?

Answer 8

It is a bipolar montage that records activIty around the circumference of the head and useful for identifying end of chain activity

Question 9

What is end of chain activity?

Answer 9

In the double banana montage, the last electrode pair of each channel displays polarity with an opposite pendaflection from all other channels. With no next channel to compare to the discharge, the activity may be misrepresented, and so changing the montage to circumferential is a must for proper interpretation.

Question 10

What is a referential average montage?

Answer 10

It is a referential montage that averages the sum of all charges from the Electrodes on the scalp, and it is useful for identifying focal activity represented by highest amplitudes

Question 11

What is a chain of electrodes?

Answer 11

Pairs of electrodes in specific derivations (or channels) creating a chain in longitudinal bipolar montages

Question 12

how many channels are required for a montage representation

Answer 12

16

Question 13

True or False. We cannot have an infinite number of montages - we are limited to only a certain number of montages available for use/review

Answer 13

FALSE

Question 14

name the planes on the head where electrode placements can occur and in so doing a chain is representative/visible by way of a montage

Answer 14

central (or sagital), parasagital (right and left), temporal (right and left), preauricular, frontal and parietal, circumferential

Question 15

what is pen deflection

Answer 15

The upward or downward slope of a wave based upon the relative polarity of two electrodes in a derivation/channel. Up deflection being negative and downward deflection being positive, except at end of chain where the deflection is reversed

Question 16

what is phase reversal and what is it used for?

Answer 16

When the pendaflections of two channels that have an electrode in common are either in phase or out of phase denoting a relatively positive or negative deflection between the channels themselves - used to determine the focus or focci of activity

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Question 17

Which montage is known as the sleep montage?

Answer 17

transverse montage

Question 18

which montage is used for identifying focus/focii using phase reversal

Answer 18

Longitudinal bipolar double banana montage

Question 19

name the three mostly used longitudinal bipolar montages

Answer 19

transverse, double banana and circumferential (hat)

Question 20

what is the phenomenon called where the top of a wave amplitude becomes/shows square in shape

Answer 20

blocking

Question 21

which montage attenuates signals to make high amplitude signals readable

Answer 21

ipsilateral

Question 22

which montage accentuates the waves when the amplitude is too low to make out the signal

Answer 22

contralateral

Question 23

What is a field?

Answer 23

Ever lessening amplitude in neighbouring channels from a focus

Question 24

What is the meaning of lateralized or lateralization?

Answer 24

Pertaining to one side or one hemisphere of the brain

Question 25

What is the meaning of generalized or generalization?

Answer 25

Pertaining the entire cerebral cortex