--although the fingertips, being at the extremity from the center of circulation, would be a place that systemic neuropathy symptoms would be likely to manifest early.

The problem with many neuropathies is that there are so many possible causes for them--compressive included--that attempting to narrow down the cause can often be a long and difficult process, involving a lot of tests, time, and expense, and often being more a process of elimination procedure than anything more definitive. And, unfortunately, for a significant minority of patients, no direct cause is found and they remain stubbornly in the "idiopathic" category.