--between peripheral neuropathies, especially those that are small-fiber predominant, and reflex sympathetic dystrophy/complex regional pain syndrome/erythromelalgia (there's some dispute as to whether the latter are actually different clinical syndromes or all aspects of the same one), but there are also some differences in the differential diagnosis. The major ones are that the latter syndromes are more often associated with a partiuclar traumatic event, and that they are usually associated with trophic changes in the skin as well, which is not generally associated with peripheral neuropathy.

They both may be associated not only with burning, stabbing pain and with autonomic dysfunctions, and yes, many of the same meds are used for symptom relief in both.

Since overactivity and inappropriate signal maintenance in the sympathetic neurons is thought to be one of the mechanisms involved in RSD/CRPS, one treatment that is often tried early in the course (if one can do it in time) is sympathetic nerve block, a treatment not normally done for diagnosed peripheral neuropathy.

big thanks to all of u.....i feel now that i have a slightly better understanding of the differences between PN and RSD.....the neuro didn't answer all my questions, because he said we needed to decide what we were dealing with first, and he wanted to spend the time checking out my feet.....reasonable, but frustrating.

cycleops, the biopsy is unlikely for me and that's okay, because i don't want anyone doing anything invasive if i can avoid it.....that's one of the reasons i asked about using blocks for PN......the last block didn't make a huge difference, and i'm not having another one if the (minor) improvement i had was a coincidence.

heyjoe, it sounds like PN can be as mysterious as RSD.....our gang likes to say that the initials stand for "really spooky disease", but i think at least half of all neuro problems qualify for that designation!

glentag.....i am LONG past the stage where sympathetic blocks r likely to help (or be useful for dignosis) which is one reason it's hard to pin down the cause of the foot symptoms.....i suppose some of u have run into the same thing, but with RSD it can take a long time to get a doc to believe u, let alone treat anything....i would guess that idiopathic PN could cause the same sort of problems.

i have other questions that i forgot in my first post....do noise and/or vibration trigger pain with PN?....or is that a sympathetic reaction peculiar to RSD?.....i get that with my feet, which is why i think it's just RSD spread (it feels exactly like my arms)....does anyone know if PN could be genetically related? (my mother had trigeminal nuralgia, a thought which scares the he** out of me).

i'm amazed at the understanding y'all have of RSD......i'm kind of ashamed to admit that i really don't know much about any of these neuro conditions except the one i have.........thanks again for your help!

liz