I guess there are 3 broad methodologies to quantify periheral axonal loss without taking neural biopsy

1. take a little bit of thenar muscle and/or subdermal tissue to quantify the peripheral nerve end using immunolabeling. however, since chronic peripheral nerve could induced compensatory nerve end branching. This may overestimate the nerve fiber count.

2. use intraoperative electrophysiological method such as recording nerve action potentil(NAP) or nerve conduction velocity(NCV) across the compressed segment of the nerve trunk.

3. use other nonivasive imaging such as MRI scan with DTI...i am not sure if this is workable