--that progress slowly and have more global effects over time, but these usually involve more than just the small fibers that subsume the sensations of pain and temperature.

A lot of the neuropathies that have metabolic, autoimmune, or toxic origins will progress if the cause is not discovered and treated, and they can involve the larger nerve fibers in time, so that one will begin to get more sensory symptoms and even some motor symptoms. These are often referred to as "sensorimotor" neuropathies, which indicates that the sensory symptoms are dominant but there may be some motor symptoms as well.

What kind of work-up have you had to ascertain cause? (Have you seen the Liz Jane spreadsheets for testing for neuropathic conditions--www.lizajane.org?)

One other thing--many small fiber neuopathies can involve autonomic symptoms, as most autonomic nerves, especially to the skin, are of the small fiber variety. This often takes the form of temperature regulation difficulties, sweating/blood pressure disturbances, and slower healing--there are often troubles with optimal functioning of the smaller blood vessels.

I must admit, from your initial description, this sounds like autoimmune and metabolic (particularly impaired glucose tolerance) issues should be strongly investigated. (It's absolutely possible to get neuropathies before progression to frank diabetes. Have you had a long--4-5 hour--glucose tolerance test with insulin levels drawn simultaneously done? Advanced antibody testing to components of peripheral nerve?)