As a result, Ice provides total anesthesia and relief of pain for several minute the same way as the hand becomes numb being exposed to snowballs in the winter. However, a few hours after the cessation of ice exposure, the pain recurs with vengeance due to reactive enlargement of blood vessels after the constriction of blood vessels due to exposure to ice.
This phenomenon causes excellent relief of pain with ice treatment followed by not only aggravation of pain, but damage to the nerve fibers adding sympathetic independent pain (SIP) to the original sympathetic mediated pain (SMP).
The end result is aggravation of the RSD and SIP resulting in failure of nerve blocks and then the patient is told, "You do not have RSD anymore because the nerve block did not help you and the phentolamine test proved that you do not have SMP or RSD".
In stage I, the injured area shows hyperthermia (increased temperature) rather than hypothermia.This is because of a temporary shock to the sympathetic system not being able to preserve heat and to control any heat loss over the skin of the injured area. In a matter of a few weeks, the majority of such patients (over four-fifths of RSD patients) regain the function of the sympathetic system and develop cold skin over the skin surrounding the area of nerve damage. Such patients cannot tolerate ice. If anything, ice aggravates the disease and exaggerates the constriction of the blood vessels and hypothermia (coldness) of the extremity. Even in these patients, the small central area of nerve damage at the area of maximum brunt of the trauma, an area is left with total paralysis of the sympathetic function showing as a pin-point area of hyperthermia on thermography. In these patients which are the majority of RSD patients, ice application should be avoided by all means.
In one-fifth of the cases when hyperthermia persists for a few more weeks, the patient will continue to be intolerant of heat or ice.
In stages II and III, the extremity progressively develops more and more hypothermia due to persistence of the dysfunction of the sympathetic system.
Eventually, towards the end of stage III and beginning of stage IV, in some cases the hyperthermia has a tendency to recur. This phenomenon is in part due to the fact that the patient has had repeated sympathetic ganglion blocks. The repetitive, numerous sympathetic ganglion blocks cause what is called "virtual sympathectomy". This results in gradual hyperthermia of the extremity (warming of the extremity). Even though the extremity becomes warm due to the virtual permanent damage to the sympathetic system, the pain does not get any better. In these patients, again, heat should be avoided.
Regardless of which type of heat intolerance or cold intolerance the patient is dealing with, the so-called heat and cold challenge treatment does no good in RSD patients. It only confuses the diagnosis and treatment and it should be avoided.
In many patients, in stages II and III, in the same extremity, there are islands of sympathetic paralysis, (hyperthermia) and islands of marked hypothermia due to sympathetic nerve irritation. These are the cases that do not respond properly to sympathetic nerve blocks and are classified as SIP (sympathetically independent pain)."
What happens if there are repeated applications of ice and severe damage occurs? The patient can actually accelerate through the stages, so instead of being in stage one for six months where local blocks may give significant relief they are propelled forward into stage two or three where there is no relief at all from blocks. Not only is this discouraging to the patient and sometimes the Doctor, but in many cases the Doctor and/or deciding party (WC, Insurance Company, etc.) may say "If you aren't responding to blocks then you must not have CRPS/RSD". Either not understanding the role that the application that the ice played, not knowing how severely damaging it could be, or not even having a clue that it was a factor at all. The patient is left without a correct diagnosis, many cases without an effective treatment, and now, has damaged nerves as well.
Just one more reason (and there are quite a few) why blocks can work better with some people than others, better in some stages than others, and why we can never compare our pain to other patients pain.
Hopefully, between what I have shared above and the links you will have a much better understanding of why the application of ice is not a good idea for CRPS patients and be able to share the information with your Drs and therapists. Besides the above links there are additional links on the website as well.
Hope this helps!