The Use of Thermography in the Diagnosis of CRPS: A Physician's Opinion
By Philip Getson, DO

Experts who evaluate patients with CRPS make the diagnosis based upon history and physical examination. However, because of the wide variation in symptom complexes, not every individual presents with the "classic" symptoms that are frequently associated with CRPS (e.g., temperature change, color change, and hair growth change).

In the past, attempts have been made to diagnosis CRPS with triple phase bone scans. Some literature suggests that these are about 40% accurate, but I believe that in reality the number is closer to 15%. This test is frequently non-specific in its representation, and rarely do radiologists offer a diagnosis of CRPS when they have not been provided with that historical information. Electrodiagnostic testing (EMGs), CAT Scans, MRIs, etc., have no appreciable value in assisting in the diagnosis of CRPS.

Thermography has been utilized in medical application since the 1950s. Prior to that it had, and still does have, industrial applications. The use of infrared imaging for neuromuscular purposes dates back to the 1960's and has continued despite lack of widespread acceptance. Numerous articles have been written regarding the value of thermography in the diagnosis of sympathetically mediated pain syndromes and work in this area continues. The July 2002 United States Department of Health and Human Services document on reflex sympathetic dystrophy, suggests thermography as the diagnostic tool for the evaluation of CRPS.

In the 24 years since I began using neuromuscular thermography in my practice, we have examined thousands of patients with neuromuscular disorders. Using electronic thermographic apparatus, the cameras (which were initially driven by liquid nitrogen) are now hi-tech computer-generated images that allow us to view the nervous system by measuring changes in skin temperature. These changes are controlled by the sympathetic nervous system and alterations in the sympathetics cause alterations in thermal (infrared) imaging which do not conform to dermatomal patterns.

While electrodiagnostic testing may show a radiculopathic pattern, such testing often errs because EMGs measure motor function as opposed to sensory function, which is the fundamental basis for CRPS. The mechanism of thermal imaging allows for perception of altered skin temperature to one-tenth of one degree centigrade. The lack of symmetry which is out of conformation to dermatomal distribution patterns goes a long way to confirming the clinical diagnosis of CRPS.
Measurements taken on an individual within approximately the first six months of the onset of the pathology will show the affected side to be warmer than the contra lateral side by temperature gradient in excess of 0.9 degrees centigrade (considered by this observer to be the standard for sympathetically mediated thermal asymmetry). Frequently this asymmetry exceeds 1.5 or 2 degrees and is clearly not the result of vascular pathology per se. After approximately six months the pattern changes with the affected side being the "cold side." It is therefore imperative that a history of the traumatic event which precipitated CRPSbe afforded the thermographic expert.

As can be seen from the images, the temperature differential is often dramatic. While the human hand is capable of perceiving significant temperature differential between two sides, the thermal imaging camera is hundreds of times more sensitive and the temperature scale (unlike the human hand) and can be adjusted to incorporate variations in room and human body temperature, which varies from individual to individual. Additionally, this author is currently collecting data which clearly indicates that the migratory pattern of CRPS can be documented as much as six to nine months prior to the occurrence of symptomatology in a limb that has been affected with sympathetically-mediated dysfunction, but has not yet become symptomatic at the time the images were performed. It is fascinating to see patients who offer verbal complaints (in completed schematic diagram) about one limb, yet manifest thermal abnormalities in an entirely separate area. (See attached images).

In addition to the benefits in diagnosing sympathetically mediated pain syndromes, new thermographic cameras have the potential to offer real-time imaging capabilities that could allow monitoring of an affected limb during the surgical implantation of a spinal cord stimulator. By stimulating the affected nerve (thereby causing a "warming" of the damaged limb), the surgeon could place the leads accurately and "know" they were in the exact place to afford the individual the maximum benefit to be derived from such implantation. This would reduce the randomization factor currently in place by allowing for an electronic "road map" which otherwise does not exist. Similar use of thermal imaging for surgical or chemical ablations of sympathetic nerve dysfunction is possible.

In conclusion, thermographic (infrared) imaging appears to be the best, if not only diagnostic tool, that should be utilized by the clinician for objectification of a clinical diagnosis of sympathetically mediated pain syndromes. The over-used adage, "A picture is worth 1000 words" is particularly applicable here, not only to assist the clinician in making the diagnosis, but to add verification to the patients' symptoms, particularly in instances where they have been led to believe they are "crazy" because conventional diagnostic testing does not offer objective evidence of their symptom complex.

Research on thermographic imaging is on-going, but as a diagnostic tool, much of its potential remains untapped. The number of people who have benefited from the conclusive diagnosis of CRPS by thermographic means continues to grow, thereby allowing clinicians an opportunity for earlier intervention of treatment to an affected body part.

Philip Getson, DO, has been certified by the American Academy of Thermology, the American Herschel Society, the Academy of Neuromuscular Thermology and is a Diplomate of the American Medical Infrared Association. He has lectured extensively in the field of Thermography especially as to its usage in the diagnosis of CRPS. He is currently working on three separate papers on the subject.