Myofascial pain syndrome after head and neck cancer treatment: Prevalence, risk factors, and influence on quality of life

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1 ORIGINAL ARTICLE Myofascial pain syndrome after head and neck cancer treatment: Prevalence, risk factors, and influence on quality of life Leticia Rodrigues Cardoso, MSc, 1 * Claudia Carvalho Rizzo, MD, PhD, 2 Cleyton Zanardo de Oliveira, MSc, 3 Carlos Roberto dos Santos, MD, 4 Andre Lopes Carvalho, MD, PhD 4 1 Physical Therapy Department, Barretos Cancer Hospital, Barretos, S~ao Paulo, Brazil, 2 Anesthesiology Department, Barretos Cancer Hospital, Barretos, S~ao Paulo, Brazil, 3 Biostatistics Department, Barretos Cancer Hospital, Barretos, S~ao Paulo, Brazil, 4 Head and Neck Surgery Department, Barretos Cancer Hospital, Barretos, S~ao Paulo, Brazil. Accepted 27 June 2014 Published online 25 September 2014 in Wiley Online Library (wileyonlinelibrary.com). DOI /hed ABSTRACT: Background. Patients undergoing treatment for head and neck cancer may develop myofascial pain syndrome as sequelae. The purpose of this study was to determine the prevalence, risk factors, and quality of life (QOL) related to myofascial pain syndrome. Methods. This was a prospective study including patients with head and neck cancer with at least a 1-year disease-free interval. Results. One hundred sixty-seven patients were analyzed, and myofascial pain syndrome was diagnosed in 20 (11.9%). In the multivariate analysis, hypopharyngeal tumors (odds ratio [OR] ; 95% confidence interval [CI] ) and neck dissection (OR ; 95% CI ) were independent factors for myofascial pain syndrome. The pain (p <.001) and shoulder domain (p <.001) as well as overall University of Washington Quality of Life (UW-QOL) score (p 5.006) were significantly lower in the patients with myofascial pain syndrome. Conclusion. Myofascial pain syndrome was observed in 1 of 9 patients after head and neck cancer treatment and a worse QOL was observed among them. Tumor site and neck dissection were found to be risk factors for myofascial pain syndrome. VC 2014 Wiley Periodicals, Inc. Head Neck 37: , 2015 KEY WORDS: head and neck cancer, pain, myofascial pain, physiotherapy, quality of life INTRODUCTION The sequelae of head and neck cancer treatment are related not only to aesthetic factors but more importantly to vital functions and the patient s ability to communicate, eat, and work. 1 Because of its anatomic localization alone, head and neck cancer can entail significant changes in vital functions and social interaction, disrupting the everyday life of these patients. 1,2 Pain is one factor that interferes with the quality of life (QOL) of cancer survivors. 1,3 Myofascial pain syndrome is a regional muscle pain disorder, characterized by intense, deep pain, arising from 1 or more muscles and the fascia, and by the presence of 1 or more hypersensitive regions. 4 Patients with myofascial pain syndrome can be identified by the presence of intensely painful points, known as trigger points, within palpable tense muscle bands, which can cause local or referred pain. 5 In a systematic literature review of painful cancer syndromes, a high myofascial pain syndrome prevalence could be found among regional pain syndromes, often characterized by continuous localized pain or a cramping *Corresponding author: L. Rodrigues Cardoso, Physical Therapy Department, Barretos Cancer Hospital, Antenor Duarte Villela Street, n 1331, Barretos, Sao Paulo, Brazil leticia.fisio@hcancerbarretos.com.br Contract grant sponsor: This work was funded by an Internal Institutional grant from Barretos Cancer Hospital sensation and sometimes related to surgical trauma. 6 Chaplin et al 7 found that myofascial pain syndrome was observed in 13% of patients with head and neck cancer, whereas the myofascial pain diagnosis was given by the presence of painful muscles with tender spots on palpation or painful trigger points with muscle involvement. The purpose of the present study was to determine the prevalence of, and risk factors for, QOL related to myofascial pain syndrome after head and neck cancer treatment. MATERIALS AND METHODS The present study was an observational cross-sectional study evaluating a consecutive series of patients treated at the Barretos Cancer Hospital, Brazil, which included patients aged >18 years and 80 years, with at least a 1- year disease-free interval after oncologic treatment of oral cavity, oropharyngeal, hypopharyngeal, or laryngeal cancer. Patient selection was carried out at the Head and Neck Department of the hospital between June 2011 and September 2012, and data collection as well as patient evaluation was performed at the Department of Physical Therapy. Patients with an impairment of the upper limb, diagnosis of myofascial pain syndrome, or fibromyalgia before the head and neck cancer treatment, were excluded from the study. The present study was approved by the hospital institutional review board, and all patients who participated in the study signed an informed consent form. HEAD & NECK DOI /HED DECEMBER

2 CARDOSO ET AL. TABLE 1. Frequency of myofascial pain syndrome in splenius, sternocleidomastoid, and upper trapezius muscles in patients after head and neck cancer treatment. Myofascial pain syndrome No. of patients (%) Splenius 2 (10.0) Trapezius 13 (65.0) SCM 0 (0.0) Splenius 1 SCM 1 (5.0) Splenius 1 trapezius 1 (5.0) SCM 1 trapezius 2 (10.0) SCM 1 trapezius 1 splenius 1 (5.0) Abbreviation: SCM, sternocleidomastoid. The patients were interviewed by a research nurse who administered the pain scale and the University of Washington Quality of Life (UW-QOL) questionnaire Portuguese version. A physical therapist administered the sociodemographic questionnaire and performed the physical examination of the patients, specifically of the sternocleidomastoid, splenius, and upper trapezius muscles. In each muscle, the 4 major criteria for myofascial pain syndrome diagnosis (ie, tense muscle bands, intense pain in trigger points within a tense muscle band, reproduction of pain upon pressure on the painful node, and limited range of motion because of pain), as well as 2 of the 4 minor criteria for myofascial pain syndrome diagnosis (ie, elicitation of a local twitch, visually or on palpation and pain), and an altered sensation at the site of a trigger point upon compression were evaluated. To confirm the clinical diagnosis of myofascial pain syndrome, all 4 major criteria and only 1 minor criterion must be positive. Patients exhibiting symptoms indicative of myofascial pain syndrome were subsequently evaluated by a physician specialized in pain management to confirm the diagnosis and perform adequate therapeutic planning. The statistical software SPSS for Windows v (Chicago, IL) was used for data storage and statistical analysis. A descriptive analysis of the data was performed, and the chi-square and Mann Whitney tests were applied to assess the relationship between the categorical or continuous variables of interest, respectively, and the occurrence of myofascial pain syndrome. Logistic regression was performed to evaluate independent risk factors for myofascial pain syndrome. RESULTS A total of 167 patients were studied, of which 134 (80.2%) were men, were white, age ranged from 45 to 60 TABLE 2. Association of pain intensity according to the Numerical Rating Scale with myofascial pain syndrome. No. of patients (%) by NRS-11 score 0 1 to 3 4 p-value MPS <0.001 No 71 (48.3) 44 (29.9) 32 (21.8) Yes 0 (0.0) 9 (45.0) 11 (55.0) years in 106 cases (63.4%), 121 (72.5%) had up to 8 years of education, and 110 (65.9%) were married or in a stable relationship. Of note, 152 (91.0%) were regular smokers, and 152 (91.0%) were alcohol consumers. As for the tumor site, oral cavity/oropharynx was the primary site in 81 patients (48.5%), the larynx in 73 patients (43.1%), and the hypopharynx in 13 patients (7.4%). When analyzing the clinical stage, the highest frequency was classified as T3/T4, 97 patients (58.0%), and of clinically positive lymph nodes N1/N2/N3, in 62 patients (37.1%). With respect to the proposed treatment, 12 patients (7.1%) underwent surgery alone, 23 (13.7%) radiotherapy alone, 42 (25.1%) surgery plus radiotherapy, 56 (33.5%) chemoradiation, and 34 (20.6%) a treatment composed of surgery and chemoradiation. Notably, 67 patients (40.1%) underwent neck dissection, of which 63 (94.0%) had a selective neck dissection and 4 (6.0%) had a radical neck dissection. Ninety-six patients (57.4%) reported pain, among them, 20 (11.9%) were diagnosed with myofascial pain syndrome. Of the 3 studied muscles, the trapezius muscle was the most commonly affected (80.5% of the cases), and it was exclusively affected in 65.0% of the cases (Table 1). The pain intensity was measured as 4 (pain considered as at least moderate) in 43 of the 96 patients (44.8%) who reported pain. Of note, a pain intensity of 4 was reported by 55.0% of the patients with myofascial pain syndrome as opposed to 21.1% of the cases with no myofascial pain syndrome (p <.001; Table 2). The use of pain medication was reported by 22 patients (13.2%) and the intensity of the pain was directly associated with the use of pain killers (p <.001). Among the patients with myofascial pain syndrome, 35% of them reported the use of medication (p 5.007; Table 3). In the univariate analysis, the primary tumor site at the hypopharynx (p 5.008), clinically positive lymph node (p 5.024), and performing neck dissection (p 5.016) were significantly associated with the occurrence of myofascial pain syndrome (Table 4). In the multivariate analysis, the topography of the hypopharynx exhibited a risk almost 6 times higher for TABLE 3. Comparative analysis of the use of pain control medication with pain intensity according to the numerical rating scale-11 and myofascial pain syndrome in patients after head and neck cancer treatment. No No. of patients (%) by medication status Yes NRS-11 < (97.2) 2 (2.8) (86.8) 7 (13.2) 4 30 (69.8) 13 (30.2) MPS.007 No 132 (89.8) 15 (10.2) Yes 13 (65.0) 7 (35.0) Abbreviations: NRS-11, 11-point numerical rating scale; MPS, myofascial pain syndrome. Abbreviations: NRS-11, 11-point numerical rating scale; MPS, myofascial pain syndrome HEAD & NECK DOI /HED DECEMBER 2015

3 MYOFASCIAL PAIN SYNDROME AFTER HEAD AND NECK CANCER TREATMENT TABLE 4. Association of variables with myofascial pain syndrome. No. of patients (%) by MPS status No Sex.236 Male 120 (89.6) 14 (10.4) Female 27 (81.8) 6 (18.2) Age, y.512 <45 9 (90.0) 1 (10.0) 45 and <60 91 (85.8) 15 (14.2) (92.2) 4 (7.8) Alcohol.999 No 14 (93.3) 1 (6.7) Yes 133 (87.5) 19 (12.5) Tobacco.999 No 14 (93.3) 1 (6.7) Yes 133 (87.5) 19 (12.5) Topography.008 Oral cavity/oropharynx 72 (88.9) 9 (11.1) Hypopharynx 8 (61.5) 5 (38.5) Larynx 67 (91.8) 6 (8.2) T classification.853 T1/T2 62 (88.6) 8 (11.4) T3/T4 85 (87.6) 12 (12.4) N classification.024 N0 97 (92.4) 8 (7.6) N1/N2/N3 50 (80.6) 12 (19.4) Therapeutic modalities Surgery 11 (91.7) 1 (8.3).850 RT 21 (91.3) 2 (8.7) Surgery 1 RT 38 (90.5) 4 (9.5) CRT 49 (87.5) 7 (12.5) Surgery 1 RT 1 CRT 28 (82.4) 6 (17.6) Neck dissection.016 No 93 (93.0) 7 (7.0) Yes 54 (80.6) 13 (19.4) Abbreviation: MPS, myofascial pain syndrome; RT, radiotherapy; CRT, chemoradiation therapy. the occurrence of myofascial pain syndrome compared to the topographies of the oral cavity/oropharynx and larynx (odds ratio [OR] ; 95% confidence interval [CI] ). The patients subjected to neck dissection exhibited odds that were 3 times higher for the occurrence of myofascial pain syndrome compared with patients who did not undergo neck dissection to treat Yes head and neck cancer (OR ; 95% CI ; Table 5). The QOL of the patients was analyzed using the scores from each domain of the UW-QOL in addition to the overall score for the questionnaire. With respect to the 167 patients, the 3 highest scores of the questionnaires were attributed to the domains of recreation, shoulder, and anxiety, and the 3 lowest scores were attributed to the domains of saliva, chewing, and speech. When comparing the scores of the domains of the UW-QOL with the occurrence of myofascial pain syndrome, the scores of the domains of pain and shoulder, as well as the overall score of the UW-QOL, were significantly lower in patients with myofascial pain syndrome (Table 6). DISCUSSION The prevalence of myofascial pain syndrome in patients with head and neck cancer varies in the literature. This discrepancy is mainly because of the different study populations and the lack of standardized criteria for the diagnosis of myofascial pain syndrome. In addition, the prevalence of myofascial pain syndrome is rarely investigated in the population as the diagnostic criteria are based on clinical examination, and a specific training of professionals is required for the identification of trigger points and tense muscle bands, which must be identified for the proper diagnosis of myofascial pain syndrome. In the present study, 57.4% of the patients reported pain, and 11.9% were diagnosed with myofascial pain syndrome according to the adopted criteria. The study by van Wilgen et al 8 described a 46.0% frequency of myofascial pain in patients with head and neck cancer 1 year after treatment. However, a diagnosis was only considered to be myofascial pain if the same site was considerably painful at least twice during palpation; therefore, only 1 of the 4 obligate criteria was assessed in the above study. On the other hand, Chaplin et al, 7 using a more restrictive diagnosis criteria presence of painful muscles with tender spots on palpation or painful trigger points with muscle involvement found that myofascial pain syndrome was observed in 13% of patients with head and neck cancer. Regarding the intensity of the pain, 55% of patients with myofascial pain syndrome reported pain with an intensity 4. Few studies have investigated the pain intensity in myofascial pain syndrome in this population, TABLE 5. Logistic regression for the analysis of independent risk factors for myofascial pain syndrome in a model adjusted by oncologic treatment and time from treatment. 95% CI Variables Category OR Lower limit Upper limit Topography Oral cavity/oropharynx Ref Hypopharynx Larynx Neck dissection No Ref. - - Yes Abbreviations: OR, odds ratio; 95% CI, 95% confidence interval. HEAD & NECK DOI /HED DECEMBER

4 CARDOSO ET AL. TABLE 6. Comparative analysis of the mean (SD) scores of the University of Washington Quality of Life questionnaire with myofascial pain syndrome in patients after head and neck cancer treatment. MPS No Yes Shoulder 92.1 (18.3) 66.7 (24.3) <.001 Pain 84.6 (23.1) 67.5 (16.4) <.001 Overall 83.9 (13.9) 83.7 (15.0).006 Anxiety 90.4 (18.8) 83.7 (21.8).086 Mood 89.4 (20.4) 81.2 (26.7).099 Taste 80.2 (29.9) 69.9 (30.5).099 Saliva 65.3 (31.5) 54.9 (33.0).170 Chewing 76.5 (34.2) 70.0 (29.9).214 Swallowing 82.8 (23.8) 76.7 (24.4).216 Activity 89.1 (18.2) 85.0 (18.8).241 Recreation 90.1 (20.3) 81.2 (30.2).346 Appearance 88.0 (20.9) 85.0 (22.0).441 Speech 78.7 (26.1) 76.7 (24.4).596 Abbreviation: MPS, myofascial pain syndrome. one of which is the work of Esenyel et al. 9 However, that study only assessed mean pain intensity corresponding to grade 3 of the 11-point numeric rating scale (NRS-11) in patients with myofascial pain. Among the therapeutic modalities performed on patients with head and neck cancer, neck dissection was considered to be a risk factor for the occurrence of myofascial pain syndrome. Of note, neck dissection is a surgical procedure that entails muscle involvement and a high risk of nerve lesion, including praxia. 10 Sixty-nine patients on our study underwent neck dissection, only 4 of them underwent radical neck dissection (including spinal accessory nerve [SAN] resection), and the others underwent selective neck dissection, therefore, no conclusion could be drawn for the association of SAN resection and myofascial pain syndrome (1 of those 4 was diagnosed with myofascial pain syndrome). Among the patients submitted to selective neck dissection, all of them had level II dissected (I, II, and III; or II, III, and IV), and no difference was observed when comparing those groups (data not shown). As the type of neck dissection did not influence the result, we decided to group the patients who underwent neck dissection (regardless of the type) and compare them to those who did not receive a neck dissection as part of their treatment. Despite the higher index of preservation of the SAN, neuropathy may occur through the surgical manipulation of the nerve. 11 Anatomically, this nerve is closely linked to the neck lymphatic drainage, in the lateral cervical region, and the removal of lymph nodes for diagnostic/ treatment purposes can cause a lesion or praxis to the SAN. 12,13 Lima et al 14 assessed SAN neuropathy upon neck dissection, which included an electroneuromyographic examination, and found the upper fibers of the trapezius muscle to be affected with pain and limited abduction of the arm in all patients evaluated after surgery. In this study, we did not perform a functional assessment of the SAN and this can be a limitation on finding the possible association of SAN function and the myofascial pain syndrome. We found that neck dissection, a proxy, for the SAN function (as this is at risk on the procedure) was associated with the risk for myofascial pain syndrome. For van Wilgen et al, 8 neck dissection was a predictive factor for reduced sensitivity in the neck, reduced range of motion of the neck, and pain in the shoulder. Furthermore, myofascial pain syndrome was strongly related to shoulder pain. In the study of Terrell et al, 15 neck dissection was considered to be a risk factor for the reduction of physical function scores in patients with head and neck cancer after treatment. The comparison among the treatments performed and its association with myofascial pain syndrome showed that when chemotherapy was added to the regiment, the rates of myofascial pain syndrome were higher compared to the same treatment without chemotherapy; however, this association was not statistically significant. Interestingly, we observed that patients with hypopharyngeal tumors exhibited a greater likelihood to exhibit myofascial pain syndrome, even in the multivariate analysis. We have not found studies in the literature that have assessed the hypopharynx specifically with respect to the presence of myofascial pain syndrome. We hypostatize that, as the hypopharyngeal cancer usually presents with more neck disease requiring extensive neck dissection, this might be the reason, however, the tumor site remained as an independent risk factor for myofascial pain syndrome (adjusted by neck dissection). We adjusted the multivariate model for all possible variables; however, patients with hypopharyngeal cancer presented a higher risk for myofascial pain syndrome. It is worth noting that the small number of those cases in the study make this possibly defined as outliers, moreover, this finding must be validated in further studies. The UW-QOL scores revealed a worse QOL for patients with myofascial pain syndrome, noting that a difference of 6 to 8 points in the score of the questionnaire can result in a clinically relevant worsening of the patient s QOL. 16,17 It is worth noting that a significant proportion of patients with head and neck cancer (57.4%) with no evidence of disease presented with pain, moreover, one fourth of them was classified as moderate to severe pain (NRS-11 4). Most of these patients were not receiving medication or specific treatment for the pain, which leads us to believe that pain is a neglected symptom in this population, as is the diagnosis of myofascial pain syndrome. We could conclude by our study that 1 of 9 patients will present myofascial pain syndrome after head and neck cancer treatment, being most of them undiagnosed. The hypopharyngeal tumors and the performance of neck dissection are risk factors for the occurrence of myofascial pain syndrome in this population, and patients diagnosed with myofascial pain syndrome have a worse QOL. Our findings suggest that patients undergoing neck dissection should have an evaluation by a physiotherapist and initiate rehabilitation as needed. Moreover, as soon as the myofascial pain syndrome is diagnosed, a multidisciplinary team (including a professional specialized in pain management) should take care of that patient HEAD & NECK DOI /HED DECEMBER 2015

5 MYOFASCIAL PAIN SYNDROME AFTER HEAD AND NECK CANCER TREATMENT Acknowledgments We would like to acknowledge the Teaching and Research Institute of the Barretos Cancer Hospital, notably the Centre for Researcher Support, the Post-Graduate Secretariat, and the librarians for support and help in the development of this study. REFERENCES 1. Hassan SJ, Weymuller EA Jr. Assessment of quality of life in head and neck cancer patients. Head Neck 1993;15: Mehanna HM, Morton RP. Does quality of life predict long-term survival in patients with head and neck cancer? Arch Otolaryngol Head Neck Surg 2006;132: Vartanian JG, Carvalho AL, Toyota J, Kowalski IS, Kowalski LP. Socioeconomic effects of and risk factors for disability in long-term survivors of head and neck cancer. Arch Otolaryngol Head Neck Surg 2006;132: Bron C, Dommerholt JD. Etiology of myofascial trigger points. Curr Pain Headache Rep 2012;16: Simons DG. Understanding effective treatments of myofascial trigger points. J Bodyw Mov Ther 2002;6: Chang VT, Janjan N, Jain S, Chau C. Regional cancer pain syndromes. J Palliat Med 2006;9: Chaplin JM, Morton RP. A prospective, longitudinal study of pain in head and neck cancer patients. Head Neck 1999;21: van Wilgen CP, Dijkstra PU, van der Laan BF, Plukker JT, Roodenburg JL. Morbidity of the neck after head and neck cancer therapy. Head Neck 2004;26: Esenyel M, Caglar N, Aldemir T. Treatment of myofascial pain. Am J Phys Med Rehabil 2000;79: Terrell JE, Welsh DE, Bradford CR, et al. Pain, quality of life, and spinal accessory nerve status after neck dissection. Laryngoscope 2000;110: Robbins KT, Clayman G, Levine PA, et al. Neck dissection classification update: revisions proposed by the American Head and Neck Society and the American Academy of Otolaryngology Head and Neck Surgery. Arch Otolaryngol Head Neck Surg 2002;128: Lockart RD, Hamilton GF, Fyfe FW. Anatomia del musculo trapezio y del nervio espi~nal. In: Anatomia Humana. Mexico: Interamericana; pp Petrera JE, Trojaborg W. Conduction studies along the accessory nerve and follow-up of patients with trapezius palsy. J Neurol Neurosurg Psychiatry 1984;47: Lima LP, Amar A, Lehn CN. Spinal accessory nerve neuropathy following neck dissection. Braz J Otorhinolaryngol 2011;77: Terrell JE, Ronis DL, Fowler KE, et al. Clinical predictors of quality of life in patients with head and neck cancer. Arch Otolaryngol Head Neck Surg 2004;130: Jaeschke R, Singer J, Guyatt GH. Measurement of health status. Ascertaining the minimal clinically important difference. Control Clin Trials 1989; 10: Juniper EF, Guyatt GH, Willan A, Griffith LE. Determining a minimal important change in a disease-specific quality of life questionnaire. J Clin Epidemiol 1994;47: HEAD & NECK DOI /HED DECEMBER