Electrodiagnosis 1

1. ELECTRO DIAGNOSIS

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.

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

4. STRENGTH-DURATION CURVE

5. 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.

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

7. 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

8. 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)

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

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

11. EMG CIRCUIT

12. ELECTRODES

13. MONOPOLAR NEEDLE

14. CONCENTRIC NEEDLE

15. BIPOLAR CONCENTRIC NEEDLE

16. NORMAL EMG

17. Spontaneous activity

18. ABNORMAL EMG

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

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

21. FINDINGS OF EMG