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Electromyography (EMG) and Musculoskeletal Pain

Muscles afflicted by pain exhibit abnormal electrical potential characteristics during activity and while at rest that can be identified and measured. These include spasm, hypertonus, hypotonus, fasciculation, co-contraction and/or co-activation. These findings may be indicative of central neuromotor engram changes, sympathetic modified responses to the pain stimuli, or as a result of abnormal motor end-plate characteristics.

Electrophysiologic modalities are specialized physiological tests that uniquely evaluate the electrical currents generated by nerve and muscle action potentials. Clinical interpretation of the findings depend on understanding the morphology of normal and abnormal electric waveforms of the motor and sensory nerve fibers.

Reliable testing is to be conducted within the framework of the physical examination and the clinical presentation. The knowledgeable clinician evaluates the results in terms of how disease or dysfunction alters the normal electric conduction of nerve and muscle.

The reader should strive to understand that no electrophysiological modality may replace another or is ‘superior’ to another. Different modalities aim at testing and interpreting the electric conduction of specific motor or sensory fibers, but no modality can test them all. Different modalities bring about different information regarding the electric behavior of nerve and muscle.

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Last updated on: February 22, 2011
First published on: January 1, 2007