Electrodiagnostic testing — nerve conduction velocity (NCV) studies and electromyography (EMG) — provides objective quantification of peripheral nerve and muscle function that clinical examination alone cannot provide. In podiatric medicine, electrodiagnostics serve to confirm clinical diagnoses of neuropathy, quantify its severity, localize specific nerve entrapments, and guide treatment decisions in complex cases of foot and ankle sensory and motor dysfunction.

Nerve Conduction Velocity Studies: What They Measure

NCV studies measure the electrical conduction velocity and amplitude of peripheral nerves by applying a known electrical stimulus at one point and recording the response downstream. For sensory nerves, sensory nerve action potentials (SNAPs) are measured: velocity reflects myelin integrity (demyelination slows conduction), while amplitude reflects the number of functional axons (axonal loss reduces amplitude). For motor nerves, compound motor action potentials (CMAPs) are measured: velocity, amplitude, and distal latency (the time from stimulus to muscle contraction) quantify motor fiber function. In podiatric practice, the sural nerve (sensory — lateral foot sensation), superficial peroneal nerve (sensory — dorsal foot), deep peroneal nerve (motor — extensor digitorum brevis), and posterior tibial nerve (motor — intrinsic foot muscles; sensory — plantar foot) are the primary nerves studied. For tarsal tunnel syndrome, medial and lateral plantar nerve distal motor latencies are measured bilaterally — prolongation confirms the diagnosis.

EMG: Assessing Muscle Denervation

EMG inserts a fine needle electrode into a muscle to record electrical activity at rest and during voluntary contraction. Abnormal spontaneous activity at rest — fibrillation potentials and positive sharp waves — indicates active denervation from ongoing nerve damage. Large polyphasic motor unit potentials (MUPs) during voluntary contraction indicate reinnervation (chronic nerve injury with axon sprouting). EMG of intrinsic foot muscles (extensor digitorum brevis, abductor hallucis, abductor digiti minimi) quantifies the degree of denervation atrophy from tarsal tunnel syndrome, peroneal nerve palsy, or advanced polyneuropathy. EMG is particularly useful when clinical examination suggests motor deficit but the extent is uncertain.

Clinical Applications in Podiatry

Diabetic peripheral neuropathy: NCV confirms early large-fiber neuropathy (slowed conduction velocity) before clinical symptoms manifest, enabling earlier preventive intervention; quantifies severity for staging and monitoring response to metabolic control improvements. Tarsal tunnel syndrome: bilateral posterior tibial nerve motor latency prolongation with side-to-side asymmetry confirms the diagnosis and guides decompression surgical planning. Peroneal nerve palsy/drop foot: differentiates common peroneal nerve injury from L4-L5 radiculopathy (both cause foot drop) — critical because surgical management differs entirely. Charcot-Marie-Tooth disease: characteristic demyelinating pattern (NCV < 38 m/s with uniform slowing) distinguishes CMT1 from acquired demyelinating neuropathy. Dr. Biernacki at Balance Foot & Ankle coordinates NCV/EMG referral for patients with suspected nerve entrapment or neuropathy, integrating electrodiagnostic results with clinical findings for precise diagnosis. Call (810) 206-1402.

When to See a Podiatrist

Many foot conditions can be managed conservatively at home, but some require professional evaluation. See a podiatrist promptly if you experience:

• Pain that persists for more than 2 weeks despite rest
• Swelling, redness, or warmth that isn’t improving
• Numbness, tingling, or burning in the feet
• A wound or sore that is not healing within 2 weeks
• Any foot concern if you have diabetes or poor circulation
• Nail changes that suggest fungal infection or other problems

At Balance Foot & Ankle, our three board-certified podiatrists — Dr. Tom Biernacki, Dr. Carl Jay, and Dr. Daria Gutkin — provide comprehensive foot and ankle care at our Howell and Bloomfield Township offices. Most insurance plans are accepted.