Microsoft Word - Yhteenveto_väitöskirja.ZaproudinaN_28.12.docx

Changes in the skin temperature (Tsk) are known to be connected with diseases and subsequently infrared thermography (IRT) has been proposed to be a diagnostic aid, e.g. in musculoskeletal disorders (MSD). However, mostly due to conflicting results of previous studies, IRT lost credibility. Now interest in IRT is growing again but valid methodological studies are needed in order to avoid new disillusions due to an underestimation of the limitations of the IRT. The purposes of present study were to examine the methodological properties of the IRT, including the analysis of interand intra-examiner reproducibility of measured results and cold-induced reflex Tsk changes in healthy individuals, and Tsk findings in patients with non-specific MSD such as chronic low back and neck pain, with a special focus on the general problems associates with Tsk measurements. The results indicated good inter-examiner reproducibility of the IRT results. However, the stability of Tsk findings varied from good in the core parts to poor in the distal areas of the subject. During cold provocation, Tsk changes varied extensively between individuals and measured areas; however, a good intra-individual correlation of responses was found. In MSD, differences in Tsk findings between the patients and control subjects were related to pain intensity, this being only in distal extremities. Moreover, IRT findings were strongly related to the actual Tsk and dependent on several other confounding factors. The results suggest that IRT has the potential to be an objective indicator of dysfunction of small nerve fibers through the changes in cutaneous microcirculation and thus, in the Tsk values. However, the signs of impaired Tsk regulation may vary over time which limits the usefulness of single measurements. Dynamic IRT with different provocation tests offers better possibilities to investigate the cutaneous circulation. Nevertheless, in applications such as non-specific LBP and NP, interpretation of Tsk findings is not straightfoward due to their heterogeneous origin and extensive variability, and IRT seems to be suitable for screening and observation purposes rather than for providing quantitative values. Overall, the complex regulation of skin blood flow, which is closely related to the function of the autonomic nervous system with a strong impact of individual reactivity, and variable physiological characteristics of the skin in different areas may lead to considerable variations in the Tsk values. In addition, numerous confounding factors exist. In summary, while IRT is a promising method for investigation of cutaneous circulation, certain precautions and considerations of the characteristics of skin blood flow are needed in the interpretation of the recorded Tsk values. National Library of Medical Classification: QC 457, WG 104, WL 610, WN 205, WR 102 Medical Subject Headings: Infrared Rays; Microcirculation; Musculoskeletal Diseases; Skin/blood supply; Skin Temperature; Sympathetic Nervous System; Thermography/methods