## 3 Discussion
Patients can report muscle-referred pain in the thigh only or spreading down, rarely even to the lateral edge of the foot. Moreover, the data presentation for AURP and \(\Delta\mathbb{T}^{\circ}\) separately hindered the interpretation of a positive SP test. Our last study provided the definition of a positive SP test result, which happens if the AURP occurrence with \(\Delta\mathbb{T}^{\circ}>0.3\ ^{\circ}\)C is confirmed. However, the clinical meaning of the number of thermograms that presented positive test results is not clear. As many as most of the thermograms were positive for the case presented in this study. Further studies comparing the SP test results to the clinical states are necessary. The use of MATLAB software makes thermography more objective and reliable and allows the processing of big data [30]. The automated quantitative analysis used to analyze the thermograms recorded during the SP test renders the procedure results faster and provides lots of additional information concerning the AURP phenomenon and temperature changes that depend on the time of the procedure and the clinical state of the patient. Currently, with the LBP pathomechanism complexity, the diagnosis is very challenging and requires complex clinical decision making to answer the question of what is the  
Figure 4: Detailed data of the two SP test diagnostic parameters and the number of positive vs. negative thermograms over time. Legend: (**a**) Development of the \(\Delta\mathbb{T}^{\circ}\) changes over time; (**b**) development of the area with the temperature above the highest recorded in the baseline thermogram (T0) (defined as AURP); (**c**) graph presenting the positive/negative SP test thermograms over time. more probable pain generator [31]. A novel idea in pain medicine is to manage low back pain using patients stratification based on clusters of tests and symptoms or--more importantly--on objective parameters [32]. Thus, our newly proposed diagnostic test that shows pathological autonomic reactivity in diseases that have not been considered before as related to the ANS pathological activity seems interesting. Limitation of the study  
Amplified vasoconstriction coincident with muscle-referred pain was confirmed for the first time, but it was based on one case only that was diagnosed with sciatica-like pain. Future studies considering all types of low back pain patients are necessary to assess the incidence of both types of vasomotor responses to the SP test. Moreover, the therapist who performed the dry needing in the present study was not blinded to the trigger-point diagnosis, which could have biased the results to some extent. Clinical implications  
The SP test is intended to objectively confirm muscle-referred pain as a sign of central sensitization related to muscles. Thus, it gives an opportunity to stop controversies around muscle-referred pain presence. The confirmation that both types of vasomotor responses to noxious stimuli are possible indications the sympathetic and parasympathetic involvement in the chronic pain state. It also points to the differences among patients who present with the same disease, which can possibly result in different therapeutic approach requirements. Moreover, it has been confirmed that muscle-referred pain contributes to other diseases such as shoulder pain, neck pain, headache, etc. Further studies considering the use of the SP test for the examination of other muscles that present referred pain are necessary.