Complex regional pain syndrome (CRPS) can exhibit complex symptoms which may not be measurable using certain forms of testing. For this reason, doctors often use several diagnostic procedures to diagnose the condition. Thermography is a diagnostic tool that is often used in addition to other diagnostics, such as physical examinations, bone scans, and nerve conduction studies. Thermography measures the distribution of skin temperature in affected limbs. CRPS may cause asymmetry in temperatures when compared with healthy limbs. This is due to circulation issues in body regions affected by CRPS.
CRPS and Skin Temperature
The body’s blood vessels are a significant contributor to regulation of skin temperature. In CRPS, individuals typically experience issues that cause abnormal circulation in the affected region. These issues may be caused by swelling, which may interfere with circulation. For this reason, thermography may be helpful in detecting skin temperature abnormalities caused by CRPS. Certain temperature difference patterns between a healthy limb and a CRPS-affected limb may be observed through thermography.
How Thermography Works for CRPS
Thermography uses imaging to create a visual map of a patient’s skin temperature. Thermography uses specialized cameras that are sensitive to the infrared light spectrum. The infrared light used during thermography produces brightly-colored patterns, which are presented on a liquid crystal display. Color differences in image results represent temperature differences in the observed bodily regions. These temperature differences may be useful in detecting other medical conditions in addition to CRPS.
Benefits of Thermography
Thermography may be beneficial due to its ability to measure slight temperature variations between CRPS-affected areas versus unaffected areas. The infrared technology behind thermography is extremely sensitive to the temperature scale, making it an effective procedure for temperature variation measurement. Additionally, the technology allows medical professionals to adjust the temperature scale to incorporate certain variations in the temperature of the room. Human body temperatures vary as well, which can also be incorporated into thermography measurements.
Thermography may also be used to diagnose conditions such as:
- Breast cancer, as seen by blood flow abnormalities caused by tumors
- Digital artery vasospasm, or artery constriction in the hands and feet
- Raynaud’s phenomenon, or reduced blood flow during cold or emotional stress
- Impaired spermatogenesis, a condition causing infertility in men
- Vertebral subluxation, which creates pressure or irritation in spinal nerves
- Deep vein thrombosis, or blood clotting in a vein deep inside the body
During thermography, the patient is typically exposed to a cold stress which stimulates temperature receptors in the skin. This cold stress is often measured at roughly 67 degrees Fahrenheit. During this period of cold stress exposure, the infrared camera will record images of specific points in the affected region, which is typically a limb such as an arm, hand, leg, or foot. The camera will also record the same points on the opposite, unaffected limb. Many physicians record three sets of images with roughly 10 to 12 images in each set. The image results are then compared side-by-side and evaluated by a trained physician who examines results based on standard protocols.
Data indicates that different stages of CRPS will produce different thermography results. When thermography is performed within six months of the onset of CRPS, the CRPS-affected area is often warmer in temperature than the non-affected area with which it is compared. However, after the initial period of six months, the CRPS-affected area often becomes the “cold side.” This is due to gradual physiological changes that CRPS causes over time.
There exists controversy over the effectiveness of thermography in diagnosing CRPS. Review of medical evidence and literature suggests that thermography may not be among the most effective diagnostic tools for CRPS. This is primarily due to the variation in signs and symptoms among different patients with CRPS. While some patients may display a clear temperature difference indicative of CRPS, some patients may not display a notable temperature difference. However, many experts allege that thermography offers important insight into CRPS-affected regions, as skin temperature can be a suggestive sign of the condition.
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