electrophysio exam Flashcards by SABRINA HALILI

What is electrophysiology exam

Evaluate integrity of neuromuscular system

Measures electrical activity

How well did you know this?

Not at all

Perfectly

Biofeedback

Monitoring and transforming physiologic data into understandable feedback
Enables individual to gain voluntary control over muscular or autonomic nervous system functions
Visual or auditory stimuli
Adjunct tool and not a treatment itself

How well did you know this?

Not at all

Perfectly

Evoked potentials

Applies electricity to evoke an action potential

How well did you know this?

Not at all

Perfectly

NCV

Peripheral, motor, and sensory neurons

Orthodromic and antidromic responses

How well did you know this?

Not at all

Perfectly

Orthodromic

normal

How well did you know this?

Not at all

Perfectly

Antidromic

reverse

How well did you know this?

Not at all

Perfectly

SNAP

Provides info on sensory nerve axon

Cutaneous receptors to DRG

How well did you know this?

Not at all

Perfectly

CMAP

Motor nerve fibers from origin in anterior horn cells to neuromuscular junction of muscle it innervates

How well did you know this?

Not at all

Perfectly

NCV Answers the questions:

Is there involvement of peripheral nerves?
Sensory? Motor? both?
Where?
How many?
Magnitude?
increasing/decreasing impairment?
localized/systemic disorder?

How well did you know this?

Not at all

Perfectly

NCV motor components

Stimulating electrode coming from machine
2 small electrodes applied on nerve
2 cm apart
Handheld electrodes
Cathode distal to anode
active/recording electrode: on muscle or nerve
Reference: distally placed
Ground: over bony areas for elimination of noise

How well did you know this?

Not at all

Perfectly

motor vs. sensory ncv

Stimulate sensory nerves distally instead of proximally

How well did you know this?

Not at all

Perfectly

what info do we get from ncv test

distance = Distance from stimulating to recording electrode (mm)

Latency
Conduction time between stimulus and start of muscle contraction or activation of nerve
(Msec)

How well did you know this?

Not at all

Perfectly

Latency

Conduction time between stimulus and start of muscle contraction or activation of nerve (msec)

How well did you know this?

Not at all

Perfectly

ncv =

distance/latency

How well did you know this?

Not at all

Perfectly

factors affecting ncv

Body temp
UE is 7-10 m/s faster
Proximal segments are faster
Age
Less than 3-5 yr old is slower than normal adults
>40 - gradual slowing
60-70- 10 m/sec less than middle aged

How well did you know this?

Not at all

Perfectly

in compression lesions, ncv is

reduced

How well did you know this?

Not at all

Perfectly

NMJ transmission

Also known as jolly test
Test for myasthenia gravis
Weakness of skeletal muscles
Affects diaphragm
Function of neuromuscular junction

How well did you know this?

Not at all

Perfectly

centrally evoked potentials

Generated by nervous system in response to sensory stimuli
SSEP: what we feel, light touch, pressure
VEP
BAEP
Induce a stimuli and computer reflects if stimuli was received by brain

How well did you know this?

Not at all

Perfectly

REACTION OF DEGENERATION

Faradic and galvanic test
Assessment of lower motor neuron lesions
A motorpoint is stimulated
Screening test for differentiating with normal peripheral innervation vs muscle with peripheral denervation
Not specific location
Not a standalone test
Not done at least 10 days after onset of problem
May be indicated in conditions of unexplained paralysis

How well did you know this?

Not at all

Perfectly

faradic current

Study These Flashcards

short pulse duration less than 1 msec

monophasic or asymmetrical PC

cathode is active

smooth tetanic

galvanic current

Study These Flashcards

long pulse duration >100 msec

monophasic or interrupted dc

cathode is active

brisk muscle twitch

partial RD faradic vs galvanic

Study These Flashcards

F; partial or diminished tetanic

G: partial or diminished sluggish twitches

partial RD

Study These Flashcards

degeneration of part of nerve fibers

complete RD

Study These Flashcards

degeneration of all nerve fibers

muscle tissue remains

absolute RD

degeneration of all nerve fibers; muscle is non-contractile

complete rd f vs. g

f: no contraction g: very slow, sluggish twitches

STRENGTH-DURATION CURVE AND CHRONAXIE TEST

``` After 3 weeks of nerve injury Used to check for improvements Square monophasic PC / sawtooth/ triangular Cathode is stimulating 8-10 pulse durations ```

usual pulse durations in SD curve

100, 30, 10, 3, 1, 0.3, 0.1, 0.03, 0.01 must be strong enough to depolarize threshold

rheobase

least intensity needed to elicit contraction normal: 3-35 v/2-18 ma

chronaxie

Minimum time needed to produce a muscle contraction with intensity set at twice the rheobase Normal: 0.05-0.5 msec or <1 msec

compute for chronaxie

2 x rheobase

Factors affecting sd curve

``` Skin resistance Subcutaneous tissue Skin temperature Electrode size Electrode placement Age Fatigue ```

Advantages of sd curve

Quick and easy Minimal training Economical

Disadvantages of sd curve

Provides qualitative data in relation to degree of denervation Cannot locate site of lesion Few fibers can be assessed

emg biofeedback

``` We are getting the muscle activity Determines best management for pt Can increase or decrease muscle activity Detects electrical activities Not a treatment ```

Facilitatory feedback

inc muscle activity post injury or post op

inhibitory feedback

dec muscle activity hypertonic muscles

EMG + components

Electricity produced by voluntary movement Electrical stimulator not needed Electrodes: Recording electrode: over muscle being tested Avoid crosstalk: input from other muscles Surface EMG Needle EMG: invasive Ground electrode: minimize noise

Signal amplification and filtration

Minimize distortion | Maximize signal to noise ratio

High pass filter

blocks low frequency, 5 Hz/10-20 Hz cut off

Low pass filter

blocks high frequency, 500 hz cut off

Signal rectification

Absolute value of all signals Rectification + low pass filter = linear envelope Process of traditional low pass filter = butterworth or chebyshev

Signal smooth

``` Moving average Certain amount of data are averaged using sliding window technique Root mean square Square root calculation Reflects mean power of signal Preferred method ```

EMG can determine

Muscle activation | Muscle fatigue

Muscle fatigue index

Identifies weak muscles | Determines effectivity of exercise

normal and abnormal EMG at rest

normal: (+) insertion activity, miniature endplate action potentials, no muscle action potentials abnormal: (+) fibrillations/fasciculations, complex discharges, inc or dec insertional activity

normal and abnormal EMG w mild contraction

normal: biphasic or triphasic muscle AP, mup from small amplitude potentions become progressively large amplitude potentials abnormal: polyphasic, amplitude dec or inc, altered recruitment pattern

normal and abnormal EMG with max contraction

normal: inc frequency, (N) step wise, inc interference patterns abnormal: dec interference pattern, early full interference pattern

electrophysio exam Flashcards

(48 cards)