Thermographic and clinical correlation of myofascial trigger points in the masticatory muscles

Abstract

Objectives: The aim of the study was to identify and correlate myofascial trigger points (MTPs) in the masticatory muscles, using thermography and algometry. Methods: 26 female volunteers were recruited. The surface facial area over the masseter and anterior temporalis muscles was divided into 15 subareas on each side (n 5 780). This investigation consisted of three steps. The first step involved thermographic facial examination, using lateral views. The second step involved the pressure pain threshold (PPT), marking the MTP pattern areas for referred pain (n 5 131) and local pain (n 5 282) with a coloured pencil, and a photograph of the lateral face with the head in the same position as the infrared imaging. The last step was the fusion of these two images, using dedicated software (ReporterH 8.5-SP3 Professional Edition and QuickReportH 1.2, FLIR Systems, Wilsonville, OR); and the calculation of the temperature of each point. Results: PPT levels measured at the points of referred pain in MTPs (1.28 ¡ 0.45 kgf) were significantly lower than the points of local pain in MTPs (1.73 ¡ 0.59 kgf; p , 0.05). Infrared imaging indicated differences between referred and local pain in MTPs of 0.5 u C (p , 0.05). Analysis of the correlation between the PPT and infrared imaging was done using the Spearman non-parametric method, in which the correlations were positive and moderate (0.4 # r , 0.7). The sensitivity and specificity in MTPs were 62.5% and 71.3%, respectively, for referred pain, and 43.6% and 60.6%, respectively, for local pain. Conclusion: Infrared imaging measurements can provide a useful, non-invasive and nonionizing examination for diagnosis of MTPs in masticatory muscles.

A new evaluation of heat distribution on facial skin surface by infrared thermography

“…Its principle of image formation is based on the capture and transformation of infrared radiation emitted by the human skin, into images that reflect the microcirculatory dynamics of the skin surface. 1,4,5,7,8,10,11,15,16,[19][20][21][22][23][24][25][26] In spite of various articles having approached the thermographic examination as a promising method in dentistry, 8,[10][11][12]15,16,21,27 in the world literature, up to now, there is no standardization as regards the evaluation of thermograms of the face.…”

“…This temperature affects the two sides of the body uniformly and simultaneously, resulting in thermal symmetry. 4,5,7,8,10,15,16,[20][21][22]25,27 The parameters for thermography exams are internationally defined, in order to obtain images in the nearest state of thermal equilibrium between the body skin surface and the room temperature, without shivering or sweating while the images are captured. The parameters suggested for the interpretations and evaluation of the thermograms influenced at the same way because all the volunteers were at the same environmental conditions during the images capture.…”

“…These results corroborate values found in the literature consulted, because the DT patterns considered normal for the face are ,0.3°C. 2,6,8,[10][11][12]15,16,20,22 The thermal study of small regions is more faithful than that of larger regions, because the greater the image resolution (e.g. : 76,000 pixels) of the thermographic machine sensor the better will be the capacity of identifying the changes in temperature in small regions.…”

“…Many diagnoses of diseases that affect the facial region are made by imaging methods; however, conventional technique shows a lack of information as regards functional aspects, such as regional microcirculation and the autonomous nervous system. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] Thermography is a non-invasive diagnostic imaging method used in medicine, capable of detecting, recording and producing infrared images that reflect the microcirculatory dynamics of the skin surface of individuals in real time, comprising the vascular, nervous and musculoskeletal systems, in addition to inflammatory processes, as well as endocrine and oncological conditions. 1 In order to maintain normal thermoregulation, the neurovegetative central nervous system, by means of the hypothalamus, controls the skin blood flow in a uniform and symmetrical manner, resulting in a right/left thermal pattern that is also symmetrical.…”

“…Furthermore, the examination allows greater precision in thermal quantification and monitoring of the region of interest (ROI). 15,16 Various articles [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] have evaluated thermographic quantitative changes in facial skin vasomotor neurovegetative activity, that is, they calculated the absolute temperature of the ROI and conjugated gradients. However, few researches have demonstrated a standardization in the protocol of descriptive evaluation of normal facial thermal distribution of human beings.…”