Entrapment of Sural Nerve
Uncommon. Anatomic variations in nerve are common. Originates from L5, S1 & S2.
Nerve may be injured following trauma (eg fracture of fifth metatarsal, cuboid, calcaneus); rearfoot surgery (especially lateral ankle reconstructions; achilles tendon surgery; ankle arthroscopy) or ankle sprains (nerve entrapped in scar tissue); rupture of peroneal or achilles tendons (scarring); fibrosis from connective tissue disorder; not uncommon following surgery on lateral aspect of ankle. May also be a compression type neuropathy from inflamed peroneal or achilles tendon; ill fitting boots; compression stockings; tourniquets; chronic venous insufficiency ( engorged lessor saphenous vein).
Altered sensation along lateral border of foot and posterior-lateral ankle – pain (usually burning) and numbness. Tinnel’s sign is often positive. May have swelling and tenderness plantar and posterior to lateral malleolus.
Differential diagnosis – S1 radiculopathy
Conservative not often successful – directed as cause avoid what irritates nerve (eg boot, activities). NSAID’s; braces to stabilise ankle; physical therapy (heat, manual therapy); Surgical – nerve resected from scar or fibrotic tissue