How is a nerve biopsy done?
A piece of tissue can be taken from the radial nerve, lateral cutaneous nerve but more commonly the sural nerve. About 1 to 2 cm of sural nerve is taken from the ankle. This nerve is preferred over the others as it provides more useful information for diagnosing vasculitis. The procedure is done under general or local anaesthetic. The nerve is typically divided into pieces for Histology, Electron microscopy and for tease preparation.
When is a nerve biopsy necessary?
Nerve biopsies are performed to investigate if a patient has a peripheral neuropathy where any additional information is required to confirm a diagnosis. The specimen will be examined to identify any ongoing demyelination, remyelination and regeneration.
Why is Electron microscopy necessary?
Where Histology and Immunohistochemistry are used to show inflammation , resin sections will show numbers of myelinated axons. Electron microscopy will identify the integrity of the myelin, signs of axonal loss, small amounts of amyloid ( which may not show up using conventional histological stains) and Wallerian degeneration.
Structure of normal nerve
Normal nerve structure is made up of several fascicles with an outer area called the epineurium. Each fascicle consists of a layer called the perineurium which is made up of connective tissue, fibroblasts, blood vessels and collagen. The perineurium of each fascicle surrounds the inner endoneurium which contains Schwann cells, both myelinated and unmyelinated axons, blood vessels and collagen.