Nerves Conduction

Question 1

How fast do nerves conduct.

Answer 1

50 m/s UE
40 m/s LE
up to 70 m/s healthy individuals
100 m/s in some text

Question 2

Neural Conduction Studies

Answer 2

NCS or NCV

Question 3

Electromyography

Answer 3

EMG

Question 4

Clinical Electrophysiological Testing (EMG and NCS)

Answer 4

should be used to confirm the findings of a good physical examination
ORDER History, scanning physical exam, nerve conduction testing, electromyography, assess data, come to a conclusion (diagnosis)

Question 5

Latency

Answer 5

Time 1. Time 2
What time period you expect the travel to occur. There is an expected time…anything less than the reference is good more than the reference is bad.

Question 6

Neural Conduction Studies

Answer 6

recording and measurement of

1. a compound nerve (used with both sensory and motor testing)
   - a compound muscle action potential (used with motor testing)
   - both elicited in response to a single supramaximal eletrical stimulus under standardized conditions
   - –amplitude
   - –duration
   - latency

Question 7

Needles

Answer 7

30 gauge–about the size of dry needling needles

only 1/2mm along tip is active…the rest of it is covered in teflon

Question 8

Equipment Needed

Answer 8

EMG unit with amplifier
Active Electrode (could be a needle)
Reference Electrode
Ground
Stimulator
Whatever is picking up the signal is the active electrode
Black=typically the Active Electrode
Red=reference

Question 9

Schema of a Peripheral Nerve Trunk

Answer 9

Epineurium
Perineurium
Endoneurium
—myelinated–faster
—unmyelinated–slower ( do not have nodes of Ranvier)
Neural Tissue is dependent upon a good blood supply and good Oxygen supply…ie Carpal Tunnel Syndrome typically the part of the Nerve not receiving optimal blood supply
Nerve interweaves as it travels

Question 10

Histological View of Myelinated and Unmyelinated Axons(PNS)

Answer 10

1= nucleus and cytoplasm of Schwann Cell
2=axon
3=microtubules
4=neurofilaments
5=myelin sheath
6=mesaxon
7=node of Ranvier
8=interdigitating processes of Schwann cells
9=side view of axon
10=basal lamina

Question 11

Myelin Formation

Answer 11

PNS-each schwann cell associates with only one axon, but each axon may have up to 500 schwann cells

Question 12

Basic Terms-Amplitude Duration, Positive, Negative, and Onset

Answer 12

Amplitude= size in uV’s or mV
Duration=length of time of the sensory, motor, or compound motor potential (in msec’s) 3-10msec
Positive=down (opposite what you did in math class–going down)
Negative=up (again, opposite what you did in math class-by convention–going up)
Onset- varies depending on type of test
==Motor -first deflection from isoeletric line (break in line usually onset)
==Sensory-peak of negative phase (taken to peak of the potential)–

Question 13

Basic Concept of Nerve Conduction Testing (Sensory)

Answer 13

Sensory
–latency-time one to time two (DSL) (from stimulation to Peak)
-Nerve conduction velocity
—amplitude (peak to trough)
—duration
—Expressed in uV’s (1 millionth of a volt)
SNAP=Sensory nerve action potential

Question 14

Posterior Primary Rami

Answer 14

goes to skin of back
muscles of the back
Facet Joints

Question 15

Anterior Primary Rami

Answer 15

goes to the Front of the Body

Question 16

Key concepts of “sensory nerve” Testing

Answer 16

Test only the fastest conducting 50m/s ue, 40m/s le
Tests the speed along a segment of a nerve, with no intervening synapse or other tissue types involved (eg. muscle fibers)
–NCV
-Latency

Question 17

2 different portions

Answer 17

1. if 90% ok and 10% not ok…EMG will tell us that part

2.

Question 18

Compound Motor Action Potential

Answer 18

represents the collective muscle response (expressed in mV’s one one thousandth’s of a volt)

Question 19

Motor will be longer than sensory

Answer 19

b/c it has to travel across NMJ and muscle fibers

Question 20

Sensory microvolts

Answer 20

Motor millivolts

Question 21

Motor Nerve Conduction Testing is

Answer 21

slower than the same length of a sensory nerve segment
why?
Nerve conduction–stll relatively fast
-NM junction- takes 1/1000th of a second
-Muscle fibers conduct, but are slow compared to nerves
What is shown is a distal motor latency (known distance, compared to a table of normal values)

Question 22

Electromyography

Answer 22

Small needle electrode inserted into a muscle

• -muscle has both names nerve innervation and specific root levels
• Elements examined
• At rest
• voluntary contraction
• Maximal contraction (screen fill)

Question 23

Orthrodromic

Answer 23

Normal direction

Question 24

Anthrodromic

Answer 24

Opposite the normal direction of travel

Question 25

No stimulating probe for the

Answer 25

EMG--only what the patient can voluntarily initiate Neuromuscular Junction Muscle Fibers

Question 26

Basic Concepts of Nerve Conduction Testing (motor)

Answer 26

Motor - -stimulus the same (supramaximal) - -action potential travels across - Nerve Fibers

Question 27

SO what can be shown with electrophysiological Testing

Answer 27

``` Injury involving peripheral nerves and what they impact: –  Compression (carpal tunnel syndrome) •  Note: vascular component –  Radiculopathy – compression of a ‘nerve root’ –  Polyneuropathy ( diabetes-3 extremities must be tested) –  Disease of NM synapse –  Disease of muscle •  Nerve injuries - Seddon’s classification system: –  neuropraxia •  temporary block with preservation of the axon –  axonotmesis •  disintegration and Wallerian degeneration of axon •  endoneurial sheath is preserved •  axon regeneration is possible –  neurotmesis •  entire continuity of the nerve trunk is lost ```

Question 28

Alternate Classification Scheme

Answer 28

Sunderland's System 1. neuropraixa(cross legs and foot fall asleep) 2. loss of axonal continuity with preservation of all supporting neural structures 3. disruption of both the axon and endonueral tube (perineurium intact) 4. Disruption of all neiral elements except the epineurium 5. complete neural disruption

Question 29

Patient #1

Answer 29

``` •  52 y o female •  Right hand feels ‘funny’, and awakens her from sound sleep x 2 mths •  Has difficulty manipulating objects with her right hand •  Notices that it is hard to open jars and doors •  Other elements of the history is normal •  No medications •  No family history of diabetes ``` ``` •  Physical Exam –  AROM c-spine WNL –  Normal Spurlings –  Strength BUE WNL –  Sensory: Decreased to light touch over the right thumb, index and ring finger, and adjacent palm – other WNL --Median Nerve Involvement –  MSR’s present and = BUE –  No pathological reflexes BUE –  No other special tests (e.g., Phalen’s, TOS, etc., performed) Reverse Phalens not performed ```

Question 30

Patient #1 | Electrophysiological Test

Answer 30

``` •  Sensory DSL’s (right): –  Median DSL (2.6 msec, and 3.7 msec) –  Ulnar DSL (1.8 msec, and 3.0 msec) –  Superficial radial DSL (2.8 msec) ``` ``` •  Motor DML, NCV, and Central Conduction Studies (right): –  Median DML: 4.4 msec –  Median NCV: 52 m/sec –  Ulnar DML: 3.2 msec –  Ulnar NCV: 54 m/sec ```

Question 31

``` What is your electrophysiological conclusion? Electrophysiological Test (con’t) ```

Answer 31

``` •  EMG: ALL NORMAL –  1st DI –  APB –  PT –  ECRL –  Biceps brachii –  Triceps –  Deltoid –  Supraspinatus –  Trapezius –  Middle cervical paraspinals –  Lower cervical paraspinals (if emg shows up then it is more significant issue that may require surgery....severe blood flow issues are involved if there are Muscle symptoms.) ```

Question 32

Patient #2

Answer 32

``` •  52 y o male •  Tingling in the right hand, involving thumb and index finger x 2 mths (palmar and dorsal aspect) •  Weakness of grip •  Chronic neck pain •  Right arm feels weak •  Has had trouble sleeping •  No other elements in history •  Taking blood pressure medications •  No history of diabetes •  Physical Exam –  Limited rotation and side bending right –  Positive Spurling right –  Strength: right triceps and right shoulder ER 4/5, other WNL (c5, c6) –  Sensation: decreased to light touch over right thumb, index finger and adacent palm, and over dorsum of right index finger –  MSR’s: right triceps 1+, other 2+ (c6 sensory c7 myotome) –  No pathological reflexes BUE ```

Question 33

Electrophysiological Test

Answer 33

``` •  Sensory DSL’s (right): Normal –  Median DSL (1.6 msec, and 2.7 msec) –  Ulnar DSL (1.8 msec, and 3.0 msec) –  Superficial radial DSL (2.8 msec) ``` ``` •  Motor DML, NCV, and Central Conduction Studies (right): –  Median DML: 3.6 msec –  Median NCV: 52 m/sec –  Ulnar DML: 3.2 msec –  Ulnar NCV: 54 m/sec ```

Question 34

What is your evaluation and why?

Answer 34

•  EMG (Right): –  1st DI: normal –  APB: normal –  PT: increased insertional activity, PSW’s and fibrillation potentials –  ECRL: increased insertional activity, PSW’s and (c5-6) fibrillation potentials –  Biceps brachii: normal –  Triceps: increased insertional activity, PSW’s and (c6-7) fibrillation potentials –  Deltoid: increased insertional activity, PSW’s and (c5-6) fibrillation potentials –  Supraspinatus: normal –  Trapezius: normal –  Middle cervical paraspinals: normal –  Lower cervical paraspinals: increased insertional activity, PSW’s and fibrillation potentials (root c5,6,7) (anterior muscles and Paraspinals must involve a Nerve root or Proximal to it to involve both)

Question 35

What is potentially going on? | Patient #3 - theoretical

Answer 35

``` •  Patient has prolonged DSL’s (median, ulnar), normal in superficial radial •  Normal DML’s in median and ulnar •  EMG findings –  Positive in APB, 1st DI, PT –  Normal in rest ```

Question 36

Key Points

Answer 36

``` •  Electrophysiological testing is an EXTENSION of a good physical exam •  Information is correlated •  Findings can show (for peripheral nerves, NM junction, and muscle) –  Location –  Acuity or chronicity of the injury –  Help define the severity/prognosis ```

Question 37

Key Points 2

Answer 37

``` •  Your role: –  Might order – know what to ask for –  Patient ask you what something means –  If interested, this a role that PT’s can do, but it is not entry level (takes specialized training and probably a fellowship) •  Questions? •  Let’s look at the information from a student volunteer ….. ```