Peroneal Nerve Entrapment: A Common Lower Leg Pain Generator

Figure A. The common peroneal nerve passes posterior to the fibular head at the extra point linghuo. Fibular head displacement may cause paresthesia along the Stomach and/or Gallbladder channels of the leg.

In this post, I’ll discuss Peroneal Nerve Entrapment, which is a common lower leg nerve entrapment causing “sciatica-like” sensations.

One of the most challenging aspects of a clinician’s work is to accurately determine the primary tissue causing referred pain. For example, paresthesia along the lower Gallbladder channel (below the knee) may stem from nerve impingement in the lower lumbar spine, common peroneal nerve entrapment posterior to the fibular head or possibly from a localized cutaneous nerve entrapment near GB 37. An accurate and differential diagnosis can be made through the combination of a thorough intake, observation, appropriate testing and palpation.

While nerve entrapment in the lumbar spine is well recognized as a contributor to lower leg sciatic paresthesia and assessed with common orthopedic exams, such as the straight leg and slump test, peroneal nerve entrapments are not as well recognized and yet are common in clinical practice.

Peroneal neuropathy is the third most common localized neuropathy after median and ulnar neuropathies (Baima J, 2008). Anatomically, the sciatic nerve divides just above the popliteal fossa into the common peroneal nerve (CPN) and the tibial nerve. The CPN branches to the lateral side of the knee and is most commonly injured posterior to the fibular head (Fig. A). This nerve entrapment mimics sciatica and can cause paresthesia distally along the GB channel in the leg, and ankle.

Figure B. The superficial cutaneous exits the deep fascia in very close proximity to GB 37. Acupuncture needle at GB 37 indicates potential entrapment site.

The CPN below the fibular head, innervates the peroneus longus and brevis (check out the video below for peroneus longus and brevis motor point locations and needling), a collateral branch from this nerve, the superficial cutaneous peroneal nerve (SPCN) travels anteriorly to exit the fascia profunda (deep fascia) in very close proximity to GB 37 (Fig. B). This nerve is vulnerable to compression from tightening of the fascia and also from external causes mentioned in the assessment below. When compressed, the paresthesia travels distally along the GB channel on the lateral ankle and into the top of the foot. Note that this nerve trajectory could be seen as a physical conduit between the Gallbladder luo-connecting point GB 37 and the Liver channel yuan-source point LIV 3.

Assessment

Compression of the Common Peroneal Nerve

• A dull aching to sharp stabbing pain around the head of the fibula.
• There may be aching pain along the Gallbladder channel distal to the fibular head, as the peroneus longus and/or soleus may be in spasm.
• Probable paresthesia along the Gallbladder and/ or Stomach channels of the leg.
• Assess for excessive foot pronation causing excessive internal rotation of the tibia.
• Assess for shortness of the biceps femoris muscle with the Hamstring Length Test.

Compression of Superficial Cutaneous Peroneal Nerve

• There is usually a history of overuse, such as with running sports and combined with aging. External causes can be from excessive pressure on the nerve from ski boots, heel straps, casts and tightly laced boots.
• Can occur after an inversion ankle sprain.
• Tinel’s sign on and around GB 37 can create the paresthesia.
• Active flexion, extension, inversion and eversion may increase the paresthesia.

Treatment