What is the role of electrodiagnostic testing in the evaluation of femoral nerve entrapment?

Updated: Oct 15, 2019
  • Author: Minoo Hadjari Hollis, MD; Chief Editor: Thomas M DeBerardino, MD  more...
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Answer

Electrodiagnostic testing typically is performed for diagnosis of femoral nerve entrapment, but it is also important for determining the extent of the injury and the prognosis for recovery. With electrodiagnostic testing, either surface or needle electrodes lateral to the femoral artery in the inguinal region are used for stimulation. The stimulation can be performed above and below the inguinal ligament. Disk electrodes from the vastus medialis are used to record stimulation.

A sensory study of the saphenous nerve (continuation of the sensory portion of the femoral nerve over the medial aspect of the leg and ankle) may also be performed. Needle examination should be completed for the paraspinal muscles, as well as for the iliopsoas (also L2-3) and hip adductors supplied by the obturator nerve, to help distinguish root or plexus injury from peripheral nerve injury. Needle EMG is usually the most revealing portion of the test. The examiner must look not only for denervation potentials but also for any active motor units.


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