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EMG F-response

An electromyograph (EMG) technique measuring the time required for a stimulus to propagate antidromically up an alpha motor neuron to the spinal cord & return orthodromically down the same axon. Clinical significance: - F responses allow for an assessment of the entire nerve, including the proximal segment, which is not assessed by routine motor nerve-conduction studies - semyelination is suggested if the time for an F response to appear is > 130% of the normal value - in connection with the H-reflex, recognition of abnormal conduction velocity in peripheral neuropathy is 80-90%. - conduction block in proximal nerve segments in inflammatory or demyelinating neuropathies may also be demonstrated

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electromyography (EMG)

References

  1. Harrison's Principles of Internal Medicine, 13th ed. Companion Handbook, Isselbacher et al (eds), McGraw-Hill Inc. NY, 1995, pg 694-95
  2. nlmpubs.nlm.nih.gov/hstat/ahcpr/