There are two types: 1-a full sural nerve biopsy and 2- skin-punch biopsy
The first is ‘usually’ done to confirm a diagnosis if other key test results are inconclusive….be forewarned, some doctors are ‘eager’ to do it, just to have experience doing it. There are many dangers and side effects with this process, infections during healing [something none of us need] and there will be absolutely zero, none, no feeling at that surgery site. Damage from this test is permanent.
To make it worse, many insurance companies do not cover or endorse this procedure anymore. Because of the side effects and dangers.
The second is usually done to assess ‘small fiber neuropathies’ and really doesn’t cover all the nerve damage issues CIDP’ers have. Few hospitals in the US do it on a regular basis, and also some insurance companies are not covering it yet, as it is considered ‘experimental’.
I myself encountered a neuro who was one wanting to have the ‘experience’ of doing this surgery….I met every single other CIDP diagnostic criteria there was so I flatly refused his offer, and never went to him again. I still cling to the hope that my nerves might get better. I would hate to lost that hope, and I would be even more dangerous walking with one dead foot…so to speak. Do not let any doctor rush you to do that biopsy – please, please, please!