2. Biomedical Instrumentation Electrophysiology (ENG-EMG)
Carlos E. Davila, Electrical Engineering Dept.
Southern Methodist University

3. Electroneurogram (ENG)
Nerve response along nerve periphery is then measured.
Measured by stimulating a peripheral nerve with electric shock.
Can be used to determine nerve conduction velocity:

5. 5
ENG (cont.)
hypothenar muscle + _
biphasic
stimulate ulnar
nerve

6. EE 5340/7340, SMU Electrical Engineering Department, © 2005
ENG(cont.)
right ulnar neuropathy in elbow (Aminoff) 10 6 2 L mV R
peak amplitude 10 6 2 R
latency L ms
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7. EE 5340/7340, SMU Electrical Engineering Department, © 2005
Electromyogram (EMG)
signal generated by muscle cells
amplitude: mV
freq range: 0-10,00 Hz
measurement: needle electrodes
single motor unit (SMU): smallest area of muscle tissue that can be activated by a volitional effort
SMU generates a triphasic potential having a amplitude of mV lasting 3-15 ms. Firing rate of SMU 6-30 per second.
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8. EE 5340/7340, SMU Electrical Engineering Department, © 2005
Electromyogram (EMG) Recruitment
SMU
SMU
SMU
SMU
SMU
contraction
effort
can’t distinguish
individual SMU’s
interference pattern
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9. EE 5340/7340, SMU Electrical Engineering Department, © 2005
EMG Affected by Disease
In neuropathy, diseased nerves degenerate, then regenerate.
Regenerated nerves conduct more slowly than healthy ones.
This produces a desynchronization in the EMG pattern.
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10. EE 5340/7340, SMU Electrical Engineering Department, © 2005
Evoked EMG Measurements/ENG
hypothenar muscle
healthy + _
10 ms
pathology
stimulate ulnar
nerve
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