What should be included in the physical exam of suspected superficial peroneal nerve entrapment?

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

In the setting of suspected superficial peroneal nerve entrapment, examination should include the entire course of the nerve, starting from the lower back and extending through the sciatic notch, the proximal fibula, and the lateral leg, where a muscle bulge due to a fascial defect may be palpated in some patients.

Percussion along the superficial course of the nerve over the proximal fibula, lateral leg, or anterior ankle may result in a positive Tinel sign, with reproduction of radiating pain. Direct palpation with pressure on the site of entrapment may also induce or exacerbate symptoms. Repeating the examination after a particular activity that exacerbates symptoms may produce findings not present on the initial examination at rest.

Styf described the use of three provocative tests for nerve compression at rest and again at rest after exercise in competitive athletes with symptoms suggestive of exertional compartment syndrome. [39] In the first test, pressure is applied over the anterior intermuscular septum while the patient actively dorsiflexes the ankle. In the second, the foot is passively plantarflexed and inverted at the ankle. In the third, while the patient maintains the passive stretch, gentle percussion is applied over the course of the nerve.

In some cases of superficial peroneal nerve entrapment associated with direct or indirect trauma, patients may present with symptoms of reflex sympathetic dystrophy (RSD), or complex regional pain syndrome (CRPS), which creates a diagnostic and therapeutic challenge.

Infrequently, weakness of the dorsiflexors and everters of the foot may be seen with associated foot drop in more proximal entrapments of the superficial peroneal nerve.

Occasionally, in cases of exertional compartment syndrome, measurement of the intramuscular pressure at rest after exercise may be helpful.

Injection of the nerve with lidocaine or bupivacaine just above the site of involvement can be the most valuable diagnostic tool. The patient can define the extent of relief obtained from such an injection, which can be helpful in defining the zone of injury and expected relief from surgical release or excision.


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