here, Erin, I hope this helps.

it's the best description I could find for why certain anti-depressants are used for the "freezing/burning" thing.

Nortriptyline worked for me.... good luck honey!

Central neuropathic pain is well recognized in MS and occurs in about 30% of people with MS. It is believed to be the direct result of demylination of the sensory pathways of pain and temperature. However, it is unlikely that a single sensory pathway is totally responsible. It is suspected there are multiple sensory pain pathways involved, but the exact mechanism is poorly understood.

The description of neuropathic pain varies and is often hard for people to describe. The most common description is a freezing or cold/burning sensation usually of the limbs and most often of the lower extremities.

Treatment

When looking at drugs available to treat neuropathic pain, tricyclic antidepressants are the first choice of treatment. Of these, amitriptyline is most frequently used for its pain reducing and sedating properties. Similar drugs such as nortriptyline or desipramine are used when the side effects of sedation or dryness that can occur with amitriptyline are poorly tolerated.

Tricyclic antidepressants work because they block the normal function of serotonin. It is one of the chemical substances of the nervous system involved in nerve impulse transmission.

http://groups.msn.com/MSPeople/mspain.msnw