RSD Puzzle #080

H. Hooshmand, M. D.

DIPLOMATE AMERICAN BOARD OF PSYCHIATRY AND NEUROLOGY

BOARD CERTIFIED IN ELECTROENCEPHOLOGRAPHY

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EPILEPSY, PAIN, MS

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RSD PUZZLE #80
COLD AND HEAT TOLERANCE

As you are well aware, there are early, intermediate, and late stages of RSD (stages I - IV). The stage I is referred to as reflex sympathetic dysfunction. Stage II is dystrophy. Stage III is characterized by atrophy. Stage IV is characterized by sympathetic system's eventual failure and destruction. The stage IV is also characterized by the failure of sympathetic function manifested in some patients by low, rather than high blood pressure and pulse, as well as low, rather than high regulation of the immune system.

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).

The above only reflects how sophisticated the sympathetic nervous system function is and how confusing the clinical picture is.

Even though we don't use thermography for diagnosis of RSD and we consider the diagnosis of RSD being a clinical diagnosis, thermography can shed a lot of light on the above confusing issues. Both the Mayo Clinic Group and Doctor Ochoa consider thermography as the diagnostic tool of choice for understanding the nature of the RSD pathology (see Muscle and Nerves, 1994, Cordoso and Ochoa, see Mayo Clinic Proceedings 1995).

H. Hooshmand, MD

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