I guess it can be painful and invasive, so they use other methods initially for the diagnosis. But for me, after 8 years of
tests, surgeries,
and chronic symptoms of Myelopathy
and Chiari Malformation, a nerve biopsy would have been the least of my worries.
To detect the nerve disorder, I had a Thermoregulatory Sweat Test, and an Autonomic Reflex Test which included a quantitative sudomotor axon reflex test, to diagnose damage to the small nerve fibers.