What causes peroneal mononeuropathy?

Updated: Jun 08, 2018
  • Author: Shaheen E Lakhan, MD, PhD, MS, MEd; Chief Editor: Nicholas Lorenzo, MD, MHA, CPE  more...
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Answer

Peroneal neuropathies are classically associated with external compression at the level of the fibular head.

  • The most common etiology is habitual leg crossing (which compresses this area).

  • Prolonged positioning with pressure at this area (e.g. sitting on an airplane or positioning during surgery) are other causes. Peroneal nerve entrapment has been reported at the fibular head on the hemiparetic side in stroke patients. [7]

  • Isolated acute repetitive strain injury such as repetitive kicking [8] and dancing [4] .

  • Short casts or braces around this area can be factors in external compression.

  • Other causes include operative trauma (knee surgery), fibular fracture, fibular head osteochondroma [9] , blunt or open trauma, and intrinsic masses (e.g. ganglionic cysts, schwannoma, lipoma) [10] .

  • Knee dislocation or bicruciate injury can cause peroneal nerve injury in 10-40% of cases. [11] The superficial peroneal nerve is at risk for traction injury during an ankle inversion sprain. [12] Varus deformity in osteoarthritis of the knee can result in peroneal nerve injury with conduction block at the fibular neck. [13]

  • Lack or loss of the fat pad over the fibular head due to a thin body habitus or sudden weight loss such as after bariatric surgery [14] or anorexia nervosa [15] predisposes the nerve to external compression at this site.

  • The peroneal nerve, if tethered where it dives into the peroneus longus muscle, also may be damaged by stretch injury. Causes include prolonged squatting or a sudden stretch.

  • Foot drop can be a presentation of exertional compartment syndrome. [16] It has been observed in weight lifters [6] and football players [17] and can be associated with anabolic steroid use. [18]

  • Other conditions that mimic peroneal mononeuropathy include sciatic nerve lesions. Sciatic nerve lesions involving predominantly the peroneal division are difficult to distinguish clinically. If the foot drop is associated temporally with hip surgery or trauma, then it is more likely to be due to sciatic nerve involvement.

  • L5 radiculopathy can also present with a foot drop but can be distinguished clinically from a peroneal mononeuropathy by involvement of the foot inverters.

  • Generalized neuropathy can present with slowly progressive, bilateral foot drop but also is associated with plantar flexion weakness and stocking-distribution sensory loss.

  • Clinically, the peroneal nerve may appear to be involved selectively in vasculitis, chronic inflammatory demyelinating neuropathy, hereditary neuropathy with liability to pressure palsy, or sarcoidosis. [19] Lyme disease has been reported to cause peroneal nerve palsy. [20] However, nerve conduction studies showing a more generalized or multifocal neuropathy may aid in the diagnosis.

  • Intermittent pneumatic compression to prevent deep vein thrombosis causing compression of the peroneal nerve at the fibula head may cause bilateral peroneal nerve palsy. [21]

  • Peroneal neuropathy can occur following liver transplantation. Risk factors include intraoperative positioning, poor nutritional status, tall and slender body shape, and alcoholic liver disease. [22]

  • Deep peroneal neuropathy resulting in foot drop with preserved toe extension has been rarely reported in patients with anatomical variation of an accessory deep peroneal nerve. [23]


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