A Thesis Submitted in Partial Fulfilment of the Requirements for the Degree of Doctor of Philosophy
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MYOFASCIAL TRIGGER POINTS AND INNERVATION ZONE LOCATIONS IN UPPER TRAPEZIUS MUSCLES MARCO BARBERO A thesis submitted in partial fulfilment of the requirements for the degree of Doctor of Philosophy QUEEN MARGARET UNIVERSITY 2016 1 ABSTRACT Myofascial pain syndrome is characterized by sensory, motor and autonomic symptoms, and a myofascial trigger point (MTrP) is considered the principal clinical feature. Clinicians recognise myofascial pain syndrome as an important clinical entity but many basic and clinical issues need further research. Electrophysiological studies indicate that abnormal electrical activity is detectable near MTrPs. This phenomenon has been described as endplate noise and it has been purported to be associated MTrP pathophysiology. Authors also suggest that MTrPs are located in the innervation zone (IZ) of muscles. The aim of this thesis was to describe both the location of MTrP and the IZ’ locations in the upper trapezius muscle. The hypothesis was that distance between the IZ and the MTrP in upper trapezius muscle is equal to zero. This thesis includes two preliminary studies. The first one address the reliability of surface electromyography (EMG) in locating the IZ in upper trapezius muscle, and the second one address the reliability of a manual palpation protocol in locating the MTrP in upper trapezius muscle. The intra- rater reliability of surface EMG in locating the IZ was almost perfect; with Kappa = 0.90 for operator A and Kappa = 0.92 for operator B. Also the inter- rater reliability showed an almost perfect agreement, with Kappa = 0.82. Both the operators conducted 900 estimations of IZ’ location through visual analysis of the EMG signals. The reliability of an experienced physiotherapist using a manual palpation protocol in locating the MTrP in the upper trapezius was established. An anatomical landmark system was defined and MTrP’ location established using X and Y values. The ICC values were 0.62 for X and 0.81 for Y. Twenty-four subjects with MTrP in upper trapezius were enrolled for this latter study. MTrP’ and IZ’ locations were described in 48 subjects. MTrPs were located in well-defined areas of the upper trapezius, showing a typical location with a mean distance from the IZ of 10.4 ± 5.8 mm. MTrPs in the upper trapezius are proximally located to the IZ but not overlapped by it (p = 0.6). These results extend the body of knowledge regarding the phenomenon of MTrP iperalgesia. I ACKNOWLEDGEMENTS I would like to express my appreciation and gratitude to my supervisors Dr Fiona Macmillan, Professor Nigel Gleeson and Dr Fiona Coutts. Thank you for your encouragement, advice and assistance in the completion of this thesis. I am very grateful to Dr Roberto Gatti for his scientific and clinical advice and many insightful discussions and suggestions. Thank you also to supporting me during the volunteer’s enrolment at the Vita-salute San Raffaele University. I would like to thank Professor Roberto Merletti for introducing me to surface electromyography and for teaching me the importance of research methodology. I would like to thank the University of Applied Sciences and Arts of Southern Switzerland, and especially Ivan Cinesi and Prof Andre Cavicchioli, for giving me the opportunity to carry out my doctoral research and for their financial support. Thank you also to all my colleagues for their support, particularly Dr Corrado Cescon and Professor Michele Egloff. A very special thank to Professor Marie Donaghy to inviting me to submit my research proposal to the Queen Margaret University. Lastly, I would like to thank my family for all their love and support through this long journey. II TABLES OF CONTENS ABSTRACT…………………………………………………………………………...I ACKNOWLEDGEMENTES………………………………………………………...II TABLE OF CONTENTS……………………………………………………………III LIST OF TABLES …………………………………………………………………VII LIST OF FIGURES…………………………………………………………….…VIII APPENDICES……………………………………………………………………….X PUBLICATIONS ARISING FORM THIS THESIS………………………………XI PROCEEDING ARISING FROM THIS THESIS………………………………XII ABBREVIATIONS…………………………………………………………….….XIII CHAPTER 1: GENERAL INTRODUCTION TO MYOFASCIAL TRIGGER POINTS……………………………………………………………………………….1 1.1 Musculoskeletal pain: the wider perspective………………………..2 1.2 Definition of myofascial pain syndrome and myofascial trigger point. ………………………………………………………………………...10 1.3 Additional clinical features…………………………………………….15 1.3.1 Muscle Weakness…………………………………………...15 1.3.2 Range of motion……………………………………………..16 1.3.3 Altered muscle recruitment…………………………………16 1.3.4 Autonomic component………………………………………17 1.4 Brief Historical review…………………………………………………18 1.5 Epidemiology………………………………………………..…………22 III 1.5 Aetiology and pathophysiology…………………………………….…30 1.5.1 Energy Crisis Theory……………………………………….31 1.5.2 Muscle spindle concept and the motor endplate hypothesis…………………………………………………………..32 1.5.3 The integrated trigger point hypothesis and his expansion……………………………………………………………39 1.7 Diagnosis…………………………………………………………….…46 1.8 Reliability of diagnostic criteria…………………………………….…49 1.9 Treatment…………………………………………………………….…53 1.10 Research agenda………………………………………………….…59 1.10.1 Aetiology…………………………………………………….60 1.10.2 Diagnostic gold standard……………………………….…62 1.10.3 Treatment…………………………………………………...63 CHAPTER 2: RESEARCH QUESTION…………………………………………65 2.1 Research aim, methodological aspects and ethical considerations……………………………………………………………...66 2.2 Research hypothesis…….………………………………………….…68 2.3 Research planning……….………………………………………….…69 2.4 Actual research plan…………………………………………………...71 2.5 Relevance of the project………………………………………………72 CHAPTER 3: RELIABILITY OF SURFACE EMG MATRIX IN LOCATING THE INNERVATION ZONE OF UPPER TRAPEZIUS MUSCLE…………………...74 3.1 Summary………………………………………………………………..75 3.2 Introduction……………………………………………………………..76 3.3 Materials and methods……………………………………………..…83 3.3.1 Participants…………………………………………………...83 3.3.2 Equipment………………………………………………….…84 IV 3.3.3 Experimental design…………………………………………89 3.3.4 Data…………………………………………………………...93 3.3.5 Localization of the innervation zone……………………….96 3.3.6 Statistical analysis…………………………………………...99 3.4 Results………………………………………………………………...100 3.5 Discussion…………………………………………………………….106 3.6 Limitations of the study………………………………………………110 3.7 Conclusions………………………………………………………...…112 CHAPTER 4: INTRA-RATER RELIABILITY OF AN EXPERIENCED PHYSIOTHERAPIST IN LOCATING MYOFASCIAL TRIGGER POINTS IN UPPER TRAPEZIUS MUSCLE…………………………………………………114 4.1 Summary………………………………………………………………115 4.2 Introduction……………………………………………………………116 4.3 Materials and methods………………………………………………120 4.3.1 Participants…………………………………………………121 4.3.2 Procedures……………………………………………….....123 4.3.3 Myofascial trigger point palpation protocol………………124 4.3.4 Statistical analysis………………………………………….126 4.4 Results……………………………………………………………...…128 4.5 Discussion…………………………………………………………….136 4.6 Limitations of the study………………………………………………141 4.7 Conclusions…………………………………………………………...143 CHAPTER 5: MYOFASCIAL TRIGGER POINTS AND INNERVATION ZONE LOCATIONS IN UPPER TRAPEZIUS MUSCLES……………………………144 5.1 Summary………………………………………………………………145 5.2 Introduction……………………………………………………………146 5.3 Methods……………………………………………………………….147 5.3.1 Participants……………………………………………….…148 5.3.2 Equipment………………………………………………..…152 5.3.3 Procedures……………………………………………….…154 V 5.3.4 Statistical analysis……………………………………….…157 5.4 Results………………………………………………………………...157 5.5 Discussion…………………………………………………………….164 5.6 Limitations of the study………………………………………………167 5.7 Conclusions…………………………………………………………...168 CHAPTER 6: THESIS CONCLUSIONS…………………………………….…170 6.1 Thesis conclusions ……………………………………………….…171 CHAPTER 7: AREAS OF FUTURE RESEARCH………………………….…182 7.1 Areas of future research…………………………………………….173 REFERENCES…………………………………………………………………...188 VI LIST OF TABLES Table 1.1: Number of Blue-collar workers with active or latent MTrPs is reported for 15 muscles on both sides. Table 1.2: Number of White-collar workers with active or latent MTrPs is reported for 15 muscles on both sides. Table 1.3: Prevalence of MTrPs among selected patient groups. Table 1.4: SEA recordings during 264 needle advances in 11 muscles. Table 1.5: Intra- and inter-examiner studies on MTrP manual palpation. Table 1.6: Perpetuating factors divided into three main categories. Table 3.1: Criteria to extract the epochs for the five lists. Table 3.2: Subjects’ characteristics. Table 3.3: Intra-rater percentage agreement for operator A during IZ estimations. Table 3.4: Intra-rater percentage agreement for operator B during IZ estimations. Table 3.5: Inter-rater percentage of agreement for operator A and B during IZ estimations. Table 3.6: Summary of the results, reliability analysis. Table 3.7: Summary of the results, disagreement and IZ shift analysis. Table 4.1: Orthopaedic tests. Table 4.2: Characteristics of the enrolled volunteers. Table 4.3: MTrP’ location with respect to the ALS in the two examinations for each subject. Table 5.1: Summarised results. VII LIST OF FIGURES Figure 1.1: Epidemiological data for musculoskeletal pain from the General Practice Research Database. Figure 1.2: Prevalence of musculoskeletal pain in different aged groups. Figure 1.3: Sex prevalence rates of musculoskeletal conditions from different consultation databases per 10000 people aged >15 years. Figure 1.4: Prevalence of musculoskeletal pain according to the number of painful regions. Figure 1.5: Distribution of multisite pains lasting at least 30 days among a selected population of male French workers. Figure 1.7: Trigger point in the infraspinatus muscle refers pain to the ipsilateral