Physmod_ Electrophysiologic-Examination-and-Evaluation

________ & ________ as practiced by PT encompass both the professional and technical components of the observation, recording, analysis, and interpretation of bioelectric muscle and nerve potentials, detected by means of surface or needle electrodes, for the purpose of evaluating the integrity of the neuromuscular system.

Electrophysiologic examinations and evaluations

Electrophysiologic Evaluations include

• Clinical electromyography [EMG]

• Motor and sensory nerve conduction studies
  [NCV]

• Electrodiagnostic procedures

• Other evoked potential procedures

Biofeedback

• Monitoring and transforming physiologic data into understandable feedback

• A training technique that enables an individual to gain some element of voluntary control over muscular or autonomic nervous system functions using a device that produces auditory or visual stimuli

• An adjunct tool and not a treatment in itself

Evoked Potentials

• ________

  • Tests peripheral motor & sensory neurons on both orthodromic & antidromic responses

  • Estimates the rate of movement of the induced impulse along the course of the nerve

Nerve Conduction Velocity

Nerve Conduction Velocity

• __________

  • Provides information on the sensory nerve axon and its pathway from the distal cutaneous receptors to the dorsal root ganglia

• ________

  • Assessment of motor nerve fibers from their origins in the anterior horn cells to the neuromuscular junction of the muscle that the nerve innervates

Sensory Nerve Action Potential

Compound Muscle Action Potential (CMAP)

NCV

Help clinician answer the following questions

• Involvement of peripheral nerves?

• Sensory? Motor? Both?

• Location? How many?

• Magnitude? Partial or Complete?

• Increasing/Decreasing impairment?

• Localized/Systemic disorder?

NCV Stimulating Electrodes

• __ small electrodes applied to the nerve fixed on the skin about _cm apart

• ____ electrodes

• Uses _____ monophasic PC

• _____ is distal to the anode, closest to the most proximal recording electrode

• 2 small electrodes applied to the nerve fixed on the skin about 2cm apart

• Handheld electrodes

• Uses rectangular monophasic PC

• Cathode is distal to the anode, closest to the most proximal recording electrode

NCV Stimulating : Other Electrodes

• ________: placed over the stimulated muscle/nerve

• ________: distally placed

• ________: placed on other areas usually on a bony area

• Active/Recording: placed over the stimulated muscle/nerve

• Reference: distally placed

• Ground: placed on other areas usually on a
  bony area

NCV

• _________

  • Linear distance between two points along the course of a nerve

  • Measured in ___

• __________

  • Conduction time between stimulus and the start of muscle contraction or activation of the nerve

  • Measured in ___

NCV = Distance / Latency

• Distance

  • mm

• Latency

  • msec

NCV = Distance / Latency

NCV Factors to Consider

• Body Temperature

• temperature → __ conduction velocity / _ distal latency ( INC_/DEC?)

• UE is _-_ m/s faster vs LE

• More ____ segments are faster vs distal

• Age

  • <3-5 y/o = LOWER by __% vs normal adults

  • >40 = ____ slowing vs middle-aged

  • 6th & 7th decade = __ m/sec LESS than middle-aged

• Body Temperature

• temperature → INC conduction velocity / DEC distal latency

• UE is 7-10 m/s faster vs LE

• More proximal segments are faster vs distal

• Age

  • <3-5 y/o = lower by 50% vs normal adults

  • >40 = gradual slowing vs middle-aged

  • 6th & 7th decade = 10 m/sec less than middle-aged

NCV

• Reduced in compression lesions like CTS, PNI, demyelinating disorders

Neuromuscular Junction Transmission

• Assesses the function of the neuromuscular

  junction

• Repetitive Nerve Stimulation Test (RNS)

  • a.k.a. “Jolly Test”

• Test for myasthenia gravis

Centrally Evoked Potentials

• Somatosensory Evoked Potential (SSEP)

• Visual Evoked Potential (VEP)

• Brainstem Auditory Evoked Potential (BAEP)

___________

• Aka Faradic and Galvanic Test

• Assessment of lower motor neuron lesions

• A motor point is stimulated.

Reaction of Degeneration Test

Reaction of Degeneration Test

Faradic Current

• _____ pulse duration (<1msec)

• >_-_ Hz frequency

• Monophasic or _______ PC using cathode as the active electrode

• Produces _______ or sustained contraction

• Short pulse duration (<1msec)

• >20-50 Hz frequency

• Monophasic or asymmetrical biphasic PC using cathode as the active electrode

• Produces smooth tetanic or sustained contraction

Reaction of Degeneration Test

Galvanic Current

• Long pulse duration (> or = ___ msec)

• Monophasic or _________ DC using cathode as the active electrode

• Produces brisk ________

• Long pulse duration (> or = 100msec)

• Monophasic or Interrupted DC using cathode as the active electrode

• Produces brisk muscle twitches

Reaction of Degeneration Test Interpretation

Status of Muscle Innervation → FC

• Normal Peripheral Nerve →

• Partial RD: degen of part of nerve fibers →

• Complete RD: degen of all nerve fibers; muscle tissue retains
  contractile elements →

• Absolute RD : degen of allnerve fibers; muscle tissue severely
  atrophic, fibrotic or non-contractile →

Status of Muscle Innervation → FC

• Normal Peripheral Nerve → Smooth Tetanic or sustained contraction

• Partial RD → Partial or diminished tetanic contraction

• Complete RD → No contraction

• Absolute RD → No Contraction

Reaction of Degeneration Test Interpretation

Status of Muscle Innervation → GC

• Normal Peripheral Nerve →

• Partial RD: degen of part of nerve fibers →

• Complete RD: degen of all nerve fibers; muscle tissue retains
  contractile elements →

• Absolute RD : degen of allnerve fibers; muscle tissue severely
  atrophic, fibrotic or non-contractile →

Status of Muscle Innervation → GC

• Normal Peripheral Nerve → Brisk muscle twitches

• Partial RD → Partial or diminished sluggish twitches

• Complete RD → Very slow, sluggish twitches

• Absolute RD → No Contraction

Reaction of Degeneration Test Use & Limitations

• A quick screening test for differentiating a muscle with ____ peripheral innervation vs a muscle with peripheral _____

• Not done at least ____ days after onset of the problem

• May be indicated in conditions of unexplained ______

• A quick screening test for differentiating a muscle with normal peripheral innervation vs a muscle with peripheral denervation

• Not done at least 10 days after onset of the problem

• May be indicated in conditions of unexplained
  paralysis

Strength Duration Curve & Chronaxie Test

• Electrodiagnosis of ______ nervous system disorders

• Used to assess the location, severity, and progress of peripheral ____ nerve degeneration

• Obtained by joining points that graphically represent the threshold values of stimulation (intensity) along the y-axis for various duration of stimulus (pulse duration) displayed along the x-axis

• Uses ____, _____ PC (sawtooth, triangular)

Strength Duration Curve & Chronaxie Test

• Electrodiagnosis of peripheral nervous system disorders

• Used to assess the location, severity, and progress of peripheral motor nerve degeneration

• Obtained by joining points that graphically represent the threshold values of stimulation (intensity) along the y-axis for various duration of stimulus (pulse duration) displayed along the x-axis

• Uses square, monophasic PC (sawtooth, triangular)

Strength Duration Curve & Chronaxie Test

• _____ as stimulating electrode

• May use _-_ pulse durations

  • Usually uses these pulse durations (in msec): 100, 30, 10, 3, 1, 0.3, 0.1, 0.03, 0.01

  • Longest pulse duration must be at least __ms

• Cathode as stimulating electrode

• May use 8-10 pulse durations

  • Usually uses these pulse durations (in msec): 100, 30, 10, 3, 1, 0.3, 0.1, 0.03, 0.01

  • Longest pulse duration must be at least 100ms

Strength Duration Curve & Chronaxie Test

• ________

  • Least amount of intensity needed to elicit visible muscle contraction for an indefinite duration

  • 5-35volts/ 2-18mA

• _______

  • Minimum time required to produce a muscle contraction with an intensity set at twice the rheobase

  • 0.05 - 0.5 msec or <1 msec

Rheobase

Chronaxia

Strength Duration Curve & Chronaxie Test

Factors Affecting the SD Curve

• Skin resistance

• Subcutaneous tissues (eg fats)

• Skin temperature

• Electrode size

• Electrode placement

• Age

• Fatigue

Strength Duration Curve & Chronaxie Test

Advantages

• Quick and easy to perform

• Requires minimal training

• More economica

Disadvantages

• Only provides qualitative data in relation to degree of denervation

• Cannot locate site of lesion

• Only few fibers can be assessed in large muscles
  

Volitional Potentials

_________

• Study of muscle activity

• Monitoring, detection, or assessment of skeletal muscle activity so that the information gained can be used by the patient and clinician to influence future activity of the skeletal muscle, whether for increasing or
  decreasing activity

Electromyographic Biofeedback

Electromyographic Biofeedback

• No _____ is delivered to the patient

• Electrical activities of the neuromuscular system is detected for _____ use

• Recorded upon ______ contraction of the muscle

• Not a therapeutic agent, but part of the therapeutic process

• No current is delivered to the patient

• Electrical activities of the neuromuscular system is detected for therapeutic use

• Recorded upon voluntary contraction of the muscle

• Not a therapeutic agent, but part of the therapeutic process

EMG BIOFEEDBACK

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EMG BIOFEEDBACK

Facilitatory Biofeedback

• ____ activity (post-injury or post-operatively)

• Normalize ____ functions

• Improve volitional motor control following ____ dysfunction

Inhibitory Biofeedback

• DEC muscle activity (spasticity in ____ dysfunctions)

• DEC muscle activity (due to _____ stress)

• DEC muscle activity / guarding(due to _____ pain)

Facilitatory Biofeedback

• muscle activity (post-injury or post-operatively)

• Normalize muscle functions

• Improve volitional motor control following CNS
  dysfunction

Inhibitory Biofeedback

• DEC muscle activity (spasticity in CNS dysfunctions)

• DEC muscle activity (due to postural stress)

• DEC muscle activity / guarding(due to chronic pain)

EMG BIOFEEDBACK

_____________

• Measurement of the electricity produced by
  the movement in muscle

• Involves the evaluation and recording of
  muscle activity

• Used for identifying neuromuscular diseases
  and disorders of motor control

• Instrument: electromyograph

CLINICAL ELECTROMYOGRAM (EMG)

EMG Biofeedback

• Electrodes

  • _________

    • Sensor

  • Considerations:

    • Electrode spacing

    • Crosstalk

  • ___________

    • Over bony surface

    • Used to minimize extraneous electrical activity (noise)

• Recording Electrodes

• Ground Electrode

EMG Biofeedback: Recording Electrodes

• _____ EMG ( sEMG)

  • non-invasive

• _____ EMG ( nEMG)

  • Invasive

• Surface EMG ( sEMG)

  • non-invasive

• Needle EMG ( nEMG)

  • Invasive

EMG Biofeedback

Signal Amplification & Filtration

• To _____ the signal-to-noise ratio

• To _____ the distortion of signal

Noise Sources during EMG

• Inherent noise of electrical parts inside the signal detection and recording instrument

• Ambient noise from the environment

• Motion artefacts (electrodes-skin interface)

• Inherent instability of EMG signal (random firing
  of motor units)

Signal Amplification & Filtration

• To maximize the signal-to-noise ratio

• To minimize the distortion of signal

Noise Sources during EMG

• Inherent noise of electrical parts inside the signal detection and recording instrument

• Ambient noise from the environment

• Motion artefacts (electrodes-skin interface)

• Inherent instability of EMG signal (random firing
  of motor units)

EMG Biofeedback : Signal Amplification & Filtration

• Amplification & Filtering Circuity

  • Electrodes → 1st stage amplification → High Pass filter → Low-pass filter → 2nd stage amplification → Low Pass Filter → Analog Digital Converter

• Band Pass Filtering

  • High-pass filter: attenuates contents ___ a cut-off frequency; Hz/_-_ Hz cut-off

  • Low-pass filter: attenuates contents ____ a cut-off frequency; ____ Hz cut-off

• Band Pass Filtering

  • High-pass filter: attenuates contents below a cut-off frequency; 5 Hz/10-20 Hz cut-off

  • Low-pass filter: attenuates contents above a cut-off frequency; 500 Hz cut-off

EMG Biofeedback

_________

• Taking the absolute value of the signal

• Also known as Full-wave Rectification

• Rectification + Low-pass Filter = “Linear Envelop”

• Traditional low-pass filter of rectified signal = Butterworth or Chebyshev

Signal Rectification

EMG Biofeedback : Signal Smoothing

• __________

  • Certain amount of data are averaged using the sliding window technique

• __________

  • Based on square root calculation; reflects the mean power of the signal; preferred method

Moving Average

Root Mean Square

EMG Biofeedback :Muscle Fatigue Index

__________

• Used to identify weak muscles

• Used to prove efficiency of strength training exercise

Muscle Fatigue Index

EMG Biofeedback : EMG AT REST

NORMAL

• (+) _______ activity

• ______ action potentials

• ___ muscle action potentials ( High or none?)

ABNORMAL

• (+) ________ /fasciculations

• complex discharges

• _ or _ insertional activity

NORMAL

• (+) insertion activity

• miniature endplate action potentials

• no muscle action potentials

ABNORMAL

• (+) fibrillations /fasciculations

• complex discharges

• INC or DEC insertional activity

EMG Biofeedback : EMG with Mild Contraction

NORMAL

• Usually ____ or ____ muscle AP

• Motor unit potentials (MUP) from ___ amplitude potentials → progressively ___-amplitude potentials

ABNORMAL

• _____, amplitude either increase or decrease

• Altered recruitment _____

NORMAL

• Usually biphasic or triphasic muscle AP

• Motor unit potentials (MUP) from small → amplitude potentials → progressively large-amplitude potentials

ABNORMAL

• Polyphasic, amplitude either increase or decrease

• Altered recruitment patterns

EMG Biofeedback : EMG with MAX Contraction

Normal

• ____ Frequency

• (N) stepwise ____ interference patterns

Abnormal

• ____ interference pattern

• ____ full interference pattern

Normal

• INC Frequency

• (N) stepwise INC interference patterns

Abnormal

• DEC interference pattern

• Early full interference pattern

GENERAL GUIDELINES FOR ALL ELECTROPHYSIOLOGIC TESTING

• Patient should be comfortable

• Ensure correct electrode placement

• Secure electrodes properly

• Perform first a detailed physical examination of strength, sensation, coordination, reflexes and other neuromuscular function

• Use latex gloves, goggles and gown for needle EMG

• When applying electrical stimulation, check for contraindications and precautions

DONE