This document discusses electrodiagnostic tests used to evaluate neuromuscular disorders, including nerve conduction studies and electromyography (EMG). It provides details on reaction of regeneration testing, strength-duration curves, chronaxie and rheobase measurements, galvanic twitch-tetanus ratios, nerve excitability testing, EMG motor unit action potentials, common mode rejection ratios, waveform types, EMG circuitry, electrode types, normal and abnormal EMG findings, indications for EMG testing, and findings that can be observed on EMG that provide information about muscle and nerve diseases.

2. When it is needed?
1. A patient is complaining of numbness.
2. A patient is complaining of tingling (paresthesias).
3. A patient has pain.
4. A patient has weakness.
5. A patient has a limp.
6. A patient has muscle atrophy.
7. A patient has depressed deep tendon reflexes.
8. A patient has fatigue.

4. REACTION OF REGENERATION TEST
 F-G TEST
 Faradic response-innervated muscles
 Galvanic response- innervated /denervated
 Wallarian degeneration and degeneration

5. STRENGTH-DURATION CURVE

7. CHRONOXIE & RHEOBASE
 1. The root word “rheo”
means current and “base”
means foundation: thus the
rheobase is the foundation,
or minimum, current
(stimulus strength) that will
produce a response.
 2. The root word “chrona”
means time and “axie” means
axis: chronaxie, then, is
measured along the time axis
and, thus, is a Duration that
gives a response when the
nerve is stimulated at twice
the rheobase strength.

8. GALVANIC TWITCH-TETANUS RATIO
TEST
 Continuous DC used
1 : 3.5to 6.5
 In denervation unity occurs, both happens with same
intensity

9. NERVE EXCITABILITY TEST
 MONOPHONIC PULSED CURRENT IS USED
 Between normal and affected side stimulation
amplitude difference
chronoxie amplitude
0.3 ms 3.5mA
1.0 ms 2mA

10. EMG-MUAP
 A motor unit is defined as one
motor neuron and all of the muscle fibers it
innervates. When a motor unit fires, the
impulse (called an action potential) is
carried down the motor neuron to the
muscle. The area where the nerve contacts
the muscle is called the neuromuscular
junction, or the motor end plate. After the
action potential is transmitted across the
neuromuscular junction, an action potential
is elicited in all of the innervated muscle
fibers of that particular motor unit. The sum
of all this electrical activity is known as a
motor unit action potential (MUAP)

13. CMRR-common mode rejection
ratio
S1+n - S2+n OUTPUT
 If output is less the CMRR is
high and the machine is more
reliable

14.  Biphasic/triphasic(90%)
WAVEFORM  Polyphasic(10%)

15. EMG CIRCUIT
Filters-
Rectifiers
notch
Preamplifier Amplifier –raw to Sound/osc
Signal 1mV
50x
filter, high
20-200x integrated illoscope
pass,
EMG
lowpass

16. ELECTRODES

17. MONOPOLAR NEEDLE

18. CONCENTRIC NEEDLE

19. BIPOLAR CONCENTRIC NEEDLE

20. NORMAL EMG

21. Spontaneous activity

22. ABNORMAL EMG

27. INDICATIONS
 Diseases of muscle,  Neuropathy
nerve and NMJ  Myopathy
 Radiculopathy
 Myelopathy

28. FINDINGS OF EMG
 fibrillation+ PSW-acute  High frequency
unresolved nerve injury dicharge- many causes
 Fasciculation – problem  Large MUAP-chronic
in nerve cell body or axonal injury due to new
spinal cord terminal branches
>5to7mV
 Small MUAP-myopathy
< 1mV

29. FINDINGS OF EMG