Current Diagnosis and Treatment of Myofascial Pain Syndrome in Children

By Stacy J. Peterson, MD and Lynn M. Rusy, MD
Jane B. Pettit Pain and Palliative Care Center
Children’s Hospital of Wisconsin
Medical College of Wisconsin
Milwaukee, Wisconsin

Chronic pediatric pain is a complex, yet common issue.  Chronic pediatric pain affects up to 25% of children, with a significant portion of these children suffering from Myofascial pain or juvenile fibromyalgia (JFM). Juvenile fibromyalgia (JFM) is estimated to occur in 2.1 -6% of children, with the greatest prevalence in adolescent females(1).  This also is one area of chronic pain that remains something of an enigma in both pediatric and adult patients. At times, the treatment of these disorders is even more difficult than the diagnosis. Myofascial pain and fibromyalgia may be seen as distinct or as a part of continuum, with JFM representing a more severe or widespread form of the disease.  Regardless of which of these is more accurate or appropriate, treatment and approach is often similar. Historically, Myofascial pain syndrome has been a catch all for pain that was not felt to be “Fibromyalgia”. This has likely occurred for several reasons. First, the diagnosis of fibromyalgia, especially in children remains different from their adult counterparts and not definitively defined. In addition, children or adolescents may not meet full criteria for fibromyalgia for various reasons – they may not have pain that widespread enough to qualify or they have widespread pain, but lack other symptoms or criteria required to make the diagnosis. As discussed later, pediatric responses to fibromyalgia questionnaires do differ from their adult counterparts.  This often leads to the diagnosis and treatment of “Myofascial Pain Syndrome” in children rather than a diagnosis of fibromyalgia.  Often the technicality of which disease process is present is not crucial to appropriately and successfully treat a patient.

First, let us look at the diagnosis of fibromyalgia while remembering the majority of our diagnostic criteria is extrapolated from adult data. Prior to 1990, there was no well-defined criteria for fibromyalgia. In 1990, a system with major and minor criteria was developed with the major criteria including widespread pain in at least three locations for at least three months as well as 11/18 points of tender points on digital palpation(2). There were additional minor criteria as well which will be discussed later.

In 2010/2011 these criteria were modified to remove the criteria of tender points areas of pain and other symptoms. The 2010 and 2011 criteria are only slightly different, with the 2011 criteria allowing self-reporting of symptoms rather than requiring an examiner. Part one of the new diagnostic criteria focused on the Widespread Pain Index (WPI) which looks at areas of pain reported in the past week. Notably, as few as three painful areas could qualify one as having fibromyalgia if their symptoms severity score (SS) was sufficiently high. The second part of the new criteria addresses the symptoms severity score. There are two parts to the symptom severity category, one looking at three pain categories – fatigue, waking unrefreshed and cognitive symptoms. The second part reviews 41 other associated symptoms. These symptoms are extensive and address respiratory, GI, vascular and psychological dimensions. What is important is that simply having widespread pain does not qualify one as having fibromyalgia, other central nervous system-mediated symptoms such as fatigue and memory disorders must also co-exist(3, 4).

 We do have some evidence to suggest that the 2010 criteria can be applied to the pediatric adolescent population with some modifications(4). The results of this study recommended increasing the time frame for the WPI from one week to three months and removing some of the somatic symptoms that were rarely chosen or poorly understood by the adolescents(4). Removing those symptoms limited the list to 22 of the original 41 symptoms included in the symptom severity scoring.

In 2016, the 2010/2011 criteria were slightly modified. One modification was to require a widespread pain index of at least four (rather than three). In addition, the decision was made to include a belief from the 1990 criteria, namely “fibromyalgia remains a valid construct irrespective of other diagnoses”.  Thus, if a patient meets criteria for fibromyalgia, they are considered to have fibromyalgia along with whatever other disorder(s) they may have.

When approaching either MPS or FM from a clinical perspective, a conservative multi-disciplinary approach is optimal. In general, the most difficult part of these syndromes to treat is the pain. The majority of evidence suggest that improvements in daily functioning and psychological coping exceeds that of improvements in pain scores.

First, let us look at the evidence for use of medications frequently utilized in the treatment of JFM. Unlike in the adult population, there are no medications approved by the FDA for treatment of JFM(5). In the adult population, there are three approved medications to treat fibromyalgia – duloxetine, milnacipran and pregabalin. Despite this, many medications are used by practitioners to treat Myofascial pain in children. These include serotonin-norepinephrine reuptake inhibitors, selective serotonin reuptake inhibitors, tricyclic anti-depressants, membrane stabilizers, opioids, acetaminophen, muscle relaxants, NSAIDs as well as various topical treatments. In adults there is some evidence that use of TCAs (often amitriptyline), milnacipran, pregabalin and duloxetine do improve pain and sometimes sleep and fatigue. However, some of the evidence remains weak and long-term benefits remains unclear. Other possible treatment options include treatment with cyclobenzaprine or low-dose naltrexone which do have some evidence for use in adults with FM. Again, we do not have studies in children but can cautiously prescribe some of these medications as a part of our treatment plan while awaiting further evidence. When initiating treatment with anti-depressants for mood or for pain in children, a safety discussion about the risk and black box warning should always be discussed with the family.   We strictly recommend against the use of opioids to treat Myofascial pain and opioids in children due to lack of evidence as well as risk of harm.

Unfortunately, in children, we currently do not have substantial evidence to support the use of any of these medications. Use of these is generally based on clinical experience or expert opinion. A recent study looking at pregabalin in adolescents with fibromyalgia did not find significant improvement in pain scores in children with JFM(6). When considering use of anti-depressants in children it is essential to remember that although we do not have evidence to support the use of SSNRIs or SSRIs to treat JFM, depression and/or anxiety are often present in our patients and we must adequately treat these disorders.

Given the weak evidence for use of medications in children with JFM, the focus of treatment should be on a multidisciplinary program focusing on exercise and psychological care. Cognitive behavioral therapy (CBT) has been shown to improve pain coping efficacy, reduce catastrophizing and improve functional disability(7).

We also support the use of regular exercise throughout the week. The evidence for this is mostly extrapolated from adult studies, although several studies do evaluate the effectiveness of various training program in adolescents. In the Stephens study, the group that participated in aerobic exercise exhibited improvement in fatigue, quality of life and daily functioning(8). A more recent study, The FIT Teens Program compared teens with JFM to either CBT alone or CBT with a neuromuscular training program, dedicating to 45 minutes to each component(9). Those teens randomized to both CBT and neuromuscular training exhibited greater maintenance in the reduction of pain.  What is especially important in the study is that pain was not the only outcome that improved in patients who were in the “FIT” arm of the trial. Disability, catastrophizing, depressive symptoms and fear of movement all showed improvement.  This study highlights the importance of true multimodal care, combining the two things -exercise and CBT that we know works well in treating JFM. 

Both of these previously discussed studies note a decline in some areas following discontinuation of the programs. This highlights something we know well – that continuation and adherence to an exercise program is often difficult to maintain. One key aspect to maintaining improvement in Myofascial pain and fibromyalgia in children and adolescents is ongoing exercise. Physical therapy or training for FM or MPS cannot be viewed in the same light as treatment of a sports-related injury. The problem is not resolved once PT is completed, rather it is key for patients to participate in ongoing and possibly lifelong exercise in order to maintain benefit.

In addition to the use of medications, psychological care and exercise, there is evidence to support the use of acupuncture for the treatment of fibromyalgia. In adults there is some evidence to suggest benefit although not all studies show improvement in pain or other measured outcomes(10,11).  In pediatrics, we do not have evidence specifically related to fibromyalgia, but do evidence for the benefit of acupuncture when treating other conditions such as pediatric migraine, cancer and post-surgical pain (12,13). Also important to note is that acupuncture in children is generally well tolerated, with the majority of patients reporting therapy as a pleasant experience(14,15).

Despite new advances in treatment for adults, treatment of Myofascial pain and fibromyalgia in children and adolescents remains a complex topic. As we approach treating this complex disorder of pain and CNS dysfunction, we should have treatment with a foundation in exercise and CBT.  Use of medications may be appropriate especially when treating concomitant mood disorders. Further research is needed to elucidate if known medication and alternative therapy used in adults is also beneficial in children and adolescents.

References

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