What is the pathogenesis of common peroneal nerve entrapment?

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

Peroneal nerve injuries are the most common peripheral nerve injuries of the lower limb to result from multiple traumatic injuries, such as those suffered in motor vehicle accidents. The common peroneal nerve can be injured at any location along the thigh down to the fibular head region in various forms of trauma, such as lacerations, femoral fractures, bullet wounds, and direct injury. However, most peroneal nerve injuries occur at the region of the fibular head.

As Kaminsky reported, the most common form of neural compromise in the region of the fibular head is due to compression from habitual leg crossing, compression of the nerve against a bed railing or hard mattress in debilitated patients, or prolonged immobility, such as that observed in patients under anesthesia. [29]

However, in a study of 146 cases, Piton et al noted 55 cases due to idiopathic causes, 16 due to external compression, 59 due to various traumatic causes, and nine due to intraneural and extraneural tumors. [30] Traumatic causes can include wounds and contusions, direct fractures involving the lateral knee, and direct lacerations or postoperative entrapment in suture hardware.

Common peroneal nerve injuries at the region of the fibular head include ankle sprains with associated proximal fibular fractures, knee dislocations, tibial osteotomies, total knee and hip arthroplasties, and arthroscopies. Compression from intraneural or extraneural tumors has been seen, including compression from neurilemomas, intraneural or extraneural ganglia, schwannomas, desmoid tumors, angiomas, neuromas, fibrolipomatosis hamartomas, exostosis, chondromatosis, Baker cysts, and vascular abnormalities. [31]

A number of other etiologic factors have been reported in the literature. Compression of the nerve against the fibrous or fascial layers of well-developed leg muscles in athletes has also been seen. Patients typically present with exercise-related leg pain with or without associated dermatomal numbness. Coexisting pathologies, such as those in exercise-related compartment syndromes, add to the complexity of this diagnosis.

Excessive weight loss can also be a contributing factor in patients (slimmer’s paralysis), in that rapid weight loss and anorexia can result in loss of the fat pad over the fibular head, predisposing the nerve to external compression at this site. Short casts or braces can result in external compression on the fibular neck region.

Individuals who spend long hours in a squatting position can also present with clinical evidence of peroneal nerve compression (strawberry picker’s palsy). This is likely the result of compression of the common peroneal nerve as it penetrates the fibro-osseous opening in the peroneus longus in persons with a fibrous or tight peroneal tunnel.

A rare form of common peroneal nerve injury is that associated with natural childbirth, in which the woman compresses both peroneal nerves at the fibular head by pulling back on her knees with her wrists resting on the fibular head during birthing. The nerve may also be injured during childbirth in the squatting position.

Other less common causes of common peroneal nerve entrapment include lower-limb lengthening procedures, anorexia nervosa, and paraneoplastic syndromes. Also, peroneal nerve mononeuropathies can occur in hyperthyroidism, diabetes mellitus, vasculitic disorders, and leprosy. Often, no underlying etiology can be definitively identified, and the condition is termed idiopathic.


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