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Common Peroneal Nerve Palsy — SCE Neurology MCQ

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EasyPeripheral Neuropathy & NeuromuscularCommon Peroneal Nerve PalsySCE Neurology

A 65-year-old man with a 15-year history of type 2 diabetes presents with sudden onset of painless right foot drop. He cannot dorsiflex or evert his right foot. Inversion is preserved. Sensation is reduced over the lateral calf and dorsum of the foot. NCS confirm a right common peroneal nerve lesion at the fibular head. What is the most likely mechanism?

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Correct answer: A — Compression neuropathy at the fibular head

Common peroneal (fibular) nerve palsy at the fibular head is the most common compressive mononeuropathy of the lower limb. Risk factors include weight loss, habitual leg crossing, prolonged immobility, and diabetes. It causes foot drop (weak dorsiflexion and eversion) with preserved inversion (tibialis posterior, supplied by the tibial nerve) and sensory loss over the lateral calf and foot dorsum. A: L5 radiculopathy would also affect hip abduction and foot inversion. C: Sciatic palsy would affect hamstrings and all below-knee muscles. D: Diabetic amyotrophy causes proximal thigh pain and weakness. E: PVD does not cause focal nerve palsy.

Reference: ABN Peripheral Neuropathy Guidelines; Preston & Shapiro Electromyography