In a recent study, it was found that based on medicare records, lots of money is spent with poor yeild of information on tests for peripheral neuropathy.  In fact, 1/3rd of tests run were MRI, which in our opinion is almost never indicated to provide information about the cause or treatment options for peripheral neuropathy.
The big question, however, is what tests should be done?
The common tests for peripheral neuropathy that provide valuable information include sensation and muscle exams, lab tests for various causes for neuropathy, nerve conduction tests and even epidermal nerve fiber tests.  Many of these tests should be done in a sequential fashion, with information you are looking for with each.  We never take a test "just in case".  Nor do we start with the less common causes of neuropathy in our testing.
So as you physician seeks to diagnose your peripheral neuropathy, ensure appropiate tests are taken and you understand what information will be provided from the test.