Which findings in nerve conduction studies indicate demyelination in patients with Guillain-Barre syndrome (GBS)?

Updated: Jul 14, 2021
  • Author: Michael T Andary, MD, MS; Chief Editor: Milton J Klein, DO, MBA  more...
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Signs of demyelination can include the following:

  • Nerve conduction slowing

  • Prolongation of the distal latencies

  • Prolongation or absence of the F-waves [1, 2]

  • Conduction block or dispersion of responses: Evidence frequently demonstrated at sites of natural nerve compression.

Changes on NCS should be present in at least 2 nerves in regions that are not typical for those associated with compressive mononeuropathies (preferentially in anatomically distinct areas, such as an arm and a leg or a limb and the face).

Although NCS results classically show a picture of demyelinating neuropathy in most patients, axonal neuropathy and inexcitable results are found in certain subgroups. The inexcitable studies may represent either axonopathy or severe demyelination with distal conduction block.

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