At one time, it seemed that biopsies (especially sural nerve biopsies) were all the rage, as were spinal taps. My neurologist now relies primarily on history, phyisical exam, and EMG studies to diagnose CIDP. In cases where those are equivocal, he still will move on to a skin biopsy, but only orders a spinal tap and/or nerve biopsy when absolutely necessary. There is always the prospect of permanent nerve damage with the sural nerve biopsy, but many people have little or no problems if the biopsy is done correctly. My neurologist does not do the nerve biopsy himself, and insists that the procedure be carried out by a experienced neurosurgeon. Best of luck.