Objective: This study tested whether two distinct thermographic patterns attributed to myofascial trigger points could distinguish between active and latent trigger points.
Design: A retrospective chart survey was undertaken with thermographic data divided into two groups: a) increased thermal emission only over the trigger point and b) over the area of pain referral. The criterion standard used in a blinded comparison was physical examination findings separating active from latent trigger points.
Setting: All cases were drawn from a private practice referral center for thermographic evaluation of neck and low back injuries.
Patients: A sample of 65 cases showing physical examination findings of trigger points was chosen from 229 consecutive motor vehicle accident case files.
Results: There was moderate agreement between the two methods of differentiating active from latent latent trigger points (Kappa = 0.44) with a specificity of 0.70 and a sensitivity of 0.74. When cases in which spinal segmental dysfunction were eliminated, the agreement increased (Kappa = 0.54) with specificity of 0.82 and sensitivity of 0.74.
Conclusions: Thermography may be a useful tool in distinguishing active from latent trigger points, but the thermal imaging of spinal joint dysfunction may be a compounding factor.