Electrodiagnostic I

1. ELECTRODIAGNOSTIC
Aditya Johan .R, M.Fis

2. INTRODUCTION
 Electrodiagnosis is the field of study that, by employing the science of
electrophysiology, uses electrical technology to study human neurophysiology
 Information needed to answer any questions regarding nerve injury, muscle injury,
muscle disease and prognosis can be obtained through electrodiagnostic testing

3. NEUROPHYSIOLOGIC
 Every practitioner should be well aware of the normal neurophysiologic function of the
nervous system
 Electrical signals are generated in the brain, pass through the spinal cord, and travel
into the peripheral nervous system
 These signals are carried down the nerve to the synaptic cleft, where a chemical release
of acetylcholine crosses the synaptic cleft to create an electrical discharge in the muscle,
This electrical signal causes the muscle to contract

4. NEUROMUSCULAR JUNCTION

5. ELECTROMYOGRAPH
 EMG was the first electrodiagnostic test to be developed
 This procedure involves the placement of a needle into various muscles to record
different stages of muscle activity, including rest, minimal contraction, and maximal
activity
 At rest, normal muscle is electrically silent
 Primary nerve injuries that are severe enough to create neurotmetic or axonotmetic
lesions, which result in Wallerian degeneration of the nerve, demonstrate fibrillation and
positive sharp-wave discharges at rest

6.  When a peripheral nerve is subjected to percutaneous electrical stimulation, action
potentials are induced in the innervated skeletal muscle
 The induced action potential is recorded by evoked EMG, which includes the H-wave, the
M-wave, and the F-wave

8. H WAVES
 The name H-wave was derived from that of Johann Hoffmann, who found the response
for the first time in 1918
 The H-wave or H response is a good indicator of the strength and distribution of the
stimulus input from muscle spindle to the motor neuron (Excitatory postsynaptic
potential/ EPSP)
 The H wave is commonly used, therefore, In the diagnosis of peripheral neuropathy
 The H-wave is also used to examine the state of muscle tone and spasticity, or other
movement disorders of the central nervous system

10.  Normal : Polyphasic 1-4 phase,
duration between 5-15 ms and
amplitude up to 2 mv
 Neuropathy : Polyphasic, high
amplitude and long duration Motor
Unit Action Potential
 Myopathy : Polyphasic, small
amplitude < 300 µv and short
duration of MUAP < 3 ms

15. THE END