What is the role of EMG in the workup of piriformis syndrome?

Updated: Dec 21, 2018
  • Author: Shishir Shah, DO; Chief Editor: Sherwin SW Ho, MD  more...
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Electromyography (EMG)

  • EMG can also be performed to determine neurologic or muscular changes.

  • In piriformis syndrome, EMG findings in the gluteus minimus, gluteus medius, and tensor fasciae latae muscles are normal.

  • In piriformis syndrome, abnormal patterns are found in the gluteus maximus and piriformis muscles.

  • In the case of a herniated disc, all muscles that are posteriorly and anteriorly innervated should be affected.

  • With a herniated disc, a significant delay in the Hoffman reflex, or H-reflex (motor nerve fiber response after activation of afferent sensory spindle fibers), in the affected limbs is often present during EMG. [28]

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