Conduction block as an electrophysiological phenomenon: a review of the literature

Evaluation and interpretation of electrophysiological phenomena often plays an important role in the diagnosis of neuromuscular diseases. Motor nerve conduction block is a reduction of either amplitude or area of the compound motor action potential elicited by proximal to distal motor nerve stimulation. Today, the value of conduction block in the diagnosis of demyelinating and axonal neuropathies, as well as the diagnostic criteria for these disorders, are still under discussion.Objective of the review of the literature is to highlight the value of conduction block as an electrophysiological phenomenon in the light of clinical manifestations. There is no consensus in the literature which motor response parameters should be used as partial conduction block criteria. The diversity of pathogenic forms in which conduction block can be registered does not allow to consider the phenomenon as a sign of only demyelinating lesions, and the term conduction block should be considered as a pure electrophysiological phenomenon. Different pathophysiological mechanisms of conduction block formation should be studied separately within each nosology. Conduction block detection does not allow to specify a particular diagnosis, however, in conjunction with clinical and anamnestic data, it may be the main argument in the diagnosis of a number of peripheral nerves diseases.