Which physical findings suggest deep peroneal nerve entrapment?

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

With proximal entrapment of the deep peroneal nerve, motor dysfunction may be demonstrated on regular gait examination, with presentations such as a dramatic foot drop. However, symptoms are usually more subtle and are noted only on heel walk or a hop test.

With long-standing dysfunction, plantarflexion of the ankle with extension of the toes can compress the nerve as it passes beneath the extensor retinaculum, and this can exacerbate the symptoms. Muscular atrophy may also be noted in the anterior compartment of the extensor digitorum brevis with distal entrapment of the nerve.

With distal entrapment, tenderness may be elicited along the entrapped segment of the nerve over the anterior ankle or just distal to it, and an underlying bony prominence is usually present. Provocative dorsiflexion and plantarflexion of the ankle may bring on or increase symptoms. A sensory deficit in the first webspace may also be detectable. Most patients have a positive Tinel test result over the entrapment site, commonly around the fibular neck or over the anterior ankle.

Incomplete involvement can also occur, affecting isolated sensory or motor branches. Temporary resolution of neuritic symptoms following an injection of the nerve with plain lidocaine at the site of entrapment is a good indicator that the diagnosis is correct.


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