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OPINION | GETSON
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 CRPS
be afforded the thermographic expert.
As can be seen from the images (included with this article),
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
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