Nerve Biopsy: Reasons, Procedure & What to Expect

A nerve biopsy (usually sural nerve at ankle) provides histopathological diagnosis for peripheral nerve disorders when non-invasive tests are inconclusive.

Common Indications

• Chronic inflammatory demyelinating polyneuropathy (CIDP) – confirm demyelination/onion bulbs.
• Vasculitic neuropathy – necrotizing inflammation.
• Infectious neuropathy (leprosy, Lyme, HIV, CMV).
• Hereditary neuropathies (CMT) – if genetic testing negative/inconclusive.
• Amyloidosis – Congo red+ deposits.
• Paraneoplastic/lymphomatous infiltration.
• Unexplained asymmetric/rapidly progressive neuropathy.

Procedure

1. Local anesthesia; 2–3 cm incision at posterolateral ankle.
2. Sural nerve identified, biopsied (2–3 cm segment).
3. Primary repair or leave ends (sensory loss over lateral foot).

Processing

• Teased fibers (demyelination/axonal loss).
• Plastic-embedded semi-thin sections (fascicle architecture).
• Electron microscopy (ultrastructure).
• Immunohistochemistry (inflammatory markers, amyloid).

Risks: Permanent lateral foot numbness, neuroma, infection, wound dehiscence. Reserved for diagnostic dilemmas impacting management.