2025 Workshop Handout Bundle-W35TC Needle EMG of the foot

W35TC Needle EMG of the foot - Park

Pdf Summary

This document discusses the needle electromyography (EMG) examination of the foot, emphasizing its importance in diagnosing neurogenic disorders affecting the intrinsic foot muscles, such as peripheral polyneuropathy, lumbosacral radiculopathy/plexopathy, and nerve entrapments (sciatic, deep peroneal, tibial nerves).<br /><br />The intrinsic foot muscles are mainly innervated by branches of the tibial nerve—the medial plantar nerve (MPN), lateral plantar nerve (LPN), and Baxter’s nerve (inferior calcaneal nerve)—with the extensor digitorum brevis (EDB) uniquely innervated by the deep peroneal nerve (DPN). Entrapment neuropathies commonly occur at anatomical sites like the tarsal tunnel, abductor canals, and around the medial calcaneus, with Baxter’s nerve being the most frequently entrapped.<br /><br />Needle EMG examination of the foot is underutilized due to concerns about pain and interpretation difficulties; however, studies refute excessive pain claims and confirm true spontaneous abnormal activity occurs rarely in healthy feet. The technique involves precise needle placement in various intrinsic foot muscles to detect abnormal spontaneous activity (fibrillation potentials, positive sharp waves), recruitment patterns, and motor unit morphology, aiding in localizing nerve pathology.<br /><br />Key muscles for EMG include the first and fourth dorsal interossei (LPN innervation), flexor digiti minimi brevis (LPN), abductor digiti quinti pedis (Baxter’s nerve), abductor hallucis (MPN), and extensor digitorum brevis (DPN). Correct placement and muscle activation confirmation through patient maneuvers are critical.<br /><br />The authors emphasize that needle EMG can be more sensitive and specific than nerve conduction studies for diagnosing foot nerve entrapments and that interpretation must integrate clinical presentation and other diagnostic data. Examining multiple muscles and both feet is necessary, as sole reliance on one muscle or symptom (e.g., weakness) is insufficient. Overall, the document promotes enhanced training and application of foot needle EMG to improve diagnosis of complex foot neuropathies.

Keywords

needle electromyography

foot intrinsic muscles

neurogenic disorders

peripheral polyneuropathy

lumbosacral radiculopathy

nerve entrapments

tibial nerve branches

deep peroneal nerve

Baxter's nerve

EMG diagnosis