Electrodiagnosis 1
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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.
Electrodiagnosis 1
- 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
- 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
- 20. NORMAL EMG
- 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