2022 Workshop Handout Bundle-Needle EMG of the Foot

Needle EMG of the Foot
Pdf Summary
The needle electromyography (EMG) examination of the foot is a valuable tool for evaluating neurogenic disorders affecting the intrinsic muscles of the foot. However, it is often under-utilized due to several misconceptions and lack of training. One common misconception is the belief that prolonged insertional activity in the foot muscles is a normal finding. However, recent studies have refuted this, demonstrating abnormal spontaneous activity in only 2% of healthy individuals. Another misconception is the belief that needle examination of the foot muscles is excessively painful, despite routine needle insertion in hand muscles. Additionally, there is little emphasis on training and education regarding needle EMG examination of the foot muscles.<br /><br />The anatomy of the foot and its innervation is important to understand for needle EMG examination. The intrinsic muscles of the foot receive their nerve supply from the tibial nerve branches, including the medial plantar nerve (MPN), lateral plantar nerve (LPN), and Baxter's nerve. The MPN innervates the abductor hallucis, flexor hallucis brevis, flexor digitorum brevis, and 1st lumbrical. The LPN innervates the quadratus plantae, flexor digiti minimi brevis, adductor hallucis, interossei, and 2nd-4th lumbricals. Baxter's nerve innervates the abductor digiti quinti pedis and occasionally the quadratus plantae and flexor digitorum brevis.<br /><br />The needle EMG examination of specific foot muscles is described. The first dorsal interosseus pedis (FDIP) and fourth dorsal interosseus pedis (Fourth DIP) are innervated by the LPN and can be examined by inserting the needle electrode into the respective dorsal web spaces. The flexor digiti minimi brevis (FDMB) is innervated by the LPN and can be examined by inserting the needle electrode at the lateral aspect of the forefoot. The abductor digiti quinti pedis (ADQP) is innervated by Baxter's nerve and can be examined by inserting the needle electrode at the junction of the dorsal and plantar skin. The abductor hallucis (AH) is innervated by the MPN and can be examined by inserting the needle electrode posterior to the navicular tuberosity. The extensor digitorum brevis (EDB) is innervated by the deep peroneal nerve (DPN) and can be examined by inserting the needle electrode into the lateral edge of the EDB.<br /><br />It is important to consider the clinical presentation and incorporate findings from the needle EMG examination in conjunction with other tests to make an accurate diagnosis. The needle EMG examination of the foot muscles can provide valuable information in diagnosing neurogenic disorders affecting the foot.
Keywords
needle electromyography
EMG examination
foot
neurogenic disorders
intrinsic muscles
misconceptions
training
anatomy of the foot
nerve supply
specific foot muscles