Pertinent Insights On Surgical Decompression For Common Peroneal Nerve Entrapment

Author(s): 
Stephen L. Barrett, DPM, MBA, FACFAS, FAENS

   The combination of these two anatomical factors makes this nerve especially susceptible to entrapment. An example of this is how frequently this nerve becomes injured with an inversion ankle sprain.9 The patient may complain of “ankle” pain for months after the injury and it is difficult for the practitioner to look proximally to this level for the diagnostic answer. The common peroneal (fibular) nerve has two terminal branches: the deep peroneal (fibular) nerve and the superficial peroneal (fibular) nerve. The deep peroneal (fibular) nerve provides the muscular innervation for the extensor hallucis longus tendon, the tibialis anterior tendon and the extensor digitorum longus tendon. The superficial peroneal (fibular) nerve innervates the peroneus longus (fibular) nerve and the peroneus (fibular) brevis nerve.

   The common peroneal nerve and its two terminal branches provide for a large surface area of skin neurosensory sensation with a corresponding large area on the cortical map. This can prove difficult when a portion or all of this nerve distribution is denervated by either injury or surgery.

What You Should Know About Diagnosing Nerve Entrapment

Diagnosis of entrapment of the common peroneal (fibular) nerve is very easy for the experienced practitioner but the inexperienced doctor with little lower extremity peripheral nerve experience and awareness almost never recognizes the diagnosis.

   This should not be the case as there are three simple things that even the inexperienced provider, from the standpoint of peripheral nerve surgery, can use to be virtually assured that an accurate and timely diagnosis has occurred. First, complete a thorough history of the present illness. Second, perform specific motor strength testing. Finally, consider the presence of a local provocation/and or Tinel’s sign at this known site of entrapment.10,11

   One can perform additional diagnostic testing with nerve conduction velocity (NCV) and the Pressure Specified Sensory Device (PSSD, Sensory Management Services), or via measurement of galvanic skin response.12-14

   As with any additional testing modality, the astute practitioner knows that these tests do not make a diagnosis but help augment the diagnosis with expert clinical examination. These tests also give a measure of the level of nerve involvement, which can serve a baseline for future evaluation after interventional treatment. The PSSD and galvanic skin response exams are non-painful tests, and one can use them postoperatively to evaluate nerve response after intervention. In my clinical experience, the electrodiagnostic testing has been falsely negative up to 50 percent of the time.

   The history of present illness is very important as it gives the provider a wealth of information, which can sometimes mean the difference between a successful outcome and even saving a patient’s life.

   While it sounds extreme, the history of a sudden drop foot in a young otherwise healthy patient with no metabolic disease and without a recent history of trauma gleaned from the interview must make the most experienced practitioner extremely wary of the probability that a central nervous system lesion exists. If there is no provocation sign at the fibular neck, send the patient immediately for a neurological consultation, which includes spine and brain magnetic resonance imaging (MRIs). This can save a patient’s life.

   Most symptoms of common peroneal (fibular) nerve entrapment are slow in their onset, even in patients with a history of a severe ankle sprain. Symptoms appear in middle age or later, and are often associated with an underlying metabolic disease such as diabetes, pre-diabetes, metabolic syndrome or other metabolic diseases.

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