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nerve conduction study (NCS); electroneuronography

Indications: - peripheral neuropathy - documenting the existence of a neuropathy - quantitating its severity - demonstrating the distribution of a neuropathy - identifying conduction modality involved (i.e. sensory vs motor) - provides clues as to underlying pathology (axonal vs. demyelinating) - cranial nerve disease - cranial nerve palsy - Bell's palsy - facial pain - trigeminal neuralgia - thoracic outlet syndrome - neuromuscular disease - muscular atrophy Procedure: - tests of peripheral nerves - performed by stimulating a nerve at one point & measuring the action potential either at another point along the nerve (sensory conduction) or of the muscle innervated by the nerve (motor conduction) - apparently hand-held device available [4] Interpretation: 1) normal conduction velocity (adults) - arms: 50-70 m/s - legs: 40-60 m/s 2) patterns a) demyelinating neuropathies - slow conduction velocity - prolonged distal latency b) axonal neuropathies - reduced amplitude of motor or sensory nerve action potential

Related

nerve conduction

Specific

facial nerve conduction study needle electromyography with nerve conduction study

General

electrophysiologic measurement

References

  1. nlmpubs.nlm.nih.gov/hstat/ahcpr/
  2. Harrison's Principles of Internal Medicine, 13th ed. Companion Handbook, Isselbacher et al (eds), McGraw-Hill Inc. NY, 1995, pg 5-6
  3. Medical Knowledge Self Assessment Program (MKSAP) 11, 17. American College of Physicians, Philadelphia 1998, 2015
  4. Young K, Sofair A, Chavey WE Carpal Tunnel Syndrome Guidelines Published Physician's First Watch, March 4, 2016 David G. Fairchild, MD, MPH, Editor-in-Chief Massachusetts Medical Society http://www.jwatch.org - Guideline on the Treatment of Carpal Tunnel Syndrome American Association of Orthopedic Surgeons (AAOS) http://www.aaos.org/Research/guidelines/CTStreatmentguide.asp