Thermography has been used effectively as an objective test in the assessment of pain. Cutaneous temperature at rest is largely controlled by the sympathetic nervous system (vasoconstrictor nerves) which closely parallel the somatic sensory nerve distribution. Therefore, when pain syndromes are present they affect the sympathetic nervous system, changes in cutaneous blood flow reflects the physiologic response to pain, creating an altered skin temperature that is recorded by the infrared imaging device.
Thermography has been found to be a useful tool for the objective documentation of sensory and sympathetic dysfunction in peripheral nerves with cutaneous projections, as malfunctioning areas can be reliably demonstrated and documented. While the skin provides clues to diagnose systemic diseases, it is also a window that allows us to monitor the health of our blood vessels and nerves.
The sympathetic system is largely responsible for the control of surface skin, innervating all tissue including muscle, the ligament, synovium, tendon, fascia, dura, disc & peripheral nerve fibers, interosseous membrane neuro-lymphatic sphincters. Diseases affecting the vascular system, nerves and connective tissue will result in temperature changes detected by thermography.
Identifying areas of pain with thermography has traditionally been performed by the comparison of one side of the body to its corresponding site on the contra lateral side, using the side without pain as the patient’s “control”. Body areas are then determined to be symmetric or asymmetric to each other with regards to temperature.
What is important from a thermographic perspective is whether the resultant vasomotor response is great enough to create a change in skin temperature of greater than 1 ° C compared to the contra lateral side or to the surrounding tissue (dermatome, sclerotome or vasotome)
Sensitivity and specificity of thermography in the assessment of pain has been reported within the 80 percentile range.The more we know, the better we can treat you. Simple as that. But gathering the information is an art.
Understand simply, that we are not diagnosing conditions with thermography. In the same way that thermography cannot see cancer, it cannot see nerve or muscle. It can, however, determine the physiologic presence of abnormalities associated with these anatomically-based factors. Thermography is adjunctive, reliable and should be used whenever possible to help patients receive the best analysis of their condition and the best treatment directed at that condition.