In the adult population, the prevalence is 1.5 to 2 times as often in women than men, frequently making its first appearance during menopause2. Consistent with the adult literature, an overwhelming proportion in our cohort are female. Unlike adults where symptoms manifest for women surrounding menopause, menstruation was a hormonal trigger that flared pain and/or initially triggered it in this cohort of patients. Dysmenorrhea was an overlooked symptom in almost a third of the 18 girls in the cohort which responded to oral contraceptives. In 3 patients, CBT and OCPs were effective treatments for their FMS.
Similar to reported literature, the mean age of diagnosis in this cohort is 14.8 years which is in line with the mean age of FMS diagnosis in adolescents between 13.7 and 15.5 years12. Only 3 of the 20 patients carried a diagnosis of FMS at the time of evaluation despite all patients in this cohort meeting ACR criteria. 4 of the 20 patients carried a preexisting diagnosed of AMPS or CRPS which leads to confusion as these are not the same conditions. AMPS is an umbrella term to describe neuropathic pain that encompasses both CRPS and FMS13. CRPS is a diagnosis of exclusion marked by light touch allodynia that is usually isolated to a limb whereas FMS is characterized by widespread pain with pressure allodynia13. In the evaluation of a child with widespread musculoskeletal pain, a differential diagnoses distinct from those of adults such as juvenile idiopathic arthritis (JIA) and juvenile ankylosing spondylitis must be considered11. Dissimilar associated conditions also include hypermobility syndrome, a well-known clinical association of pediatric FMS. 81% of children diagnosed with FMS met criteria for hypermobility in a study of 338 children14,15. A quarter of our cohort has hypermobility.
Surrounding this adult validated criteria, Buskila & Ablin11 are among a limited number of researchers who have explicitly studied pediatric FMS. As in adults, pain is the cardinal symptom but in pediatric FMS also includes debilitating fatigue, headaches, sleep disturbances, abdominal pain, and a variety of neuropsychiatric problems11. All of the patients in this cohort had fatigue and sleep disturbances, over half had headaches, and a quarter had abdominal pain, mainly functional in nature. This correlates with the adult literature, sleep disorders are more common in adult FM patients than in the general population16,17. Consequently, worse perceived sleep quality is associated with greater symptom severity16,17. Cognitive factors such as catastrophizing (irrational thinking that the pain is worse than it is) and fear of movement have also been found to be poor prognostic factors in FMS2. Sleep disorders have also been documented in pediatric FMS patients, occurring in 67% of patients in another study17.Namely, children with FMS differ in sleep architecture with shortened total sleep time, prolonged sleep latency, decreased sleep efficiency, longer awake periods during sleep, and movement arousal18. These concomitant factors cumulatively result in diminished capacity to cope with pain as a child.
FMS is associated with a lifetime prevalence of psychiatric disorders, mainly major depressive disorder (MDD), generalized anxiety disorder (GAD), and post-traumatic stress disorder (PTSD). As many as 86% of adult FM patients are diagnosed with MDD, up to 60% with GAD, and up to 57% fulfil diagnostic criteria of PTSD3. 65% of the patients in our cohort were diagnosed with psychopathology. Depression and anxiety prevail in pediatric FMS similar to adults, occurring in 26.6% and 60% of patients in one study (n=94), respectively19. In our cohort, 2 patients treated with SSRIs with CBT resulted in resolution of symptom. It is unclear the mechanism behind resolution of symptoms, whether the SSRI addresses pain by acting on the descending modulating antinociceptive arm of the nervous system or by treating the mood disorder, or if it is the influence of both.
Compared to adults with FMS, stress and distress play important trigger roles in its development. Imbieterowicz19 specifically cites sexual abuse, learning disability, maternal substance abuse, parental separation, and domestic financial difficulties before the age of 7 years to be major predisposing factors. In our cohort, 35% of patients had significant psychosocial stressors; the age at which these events occurred was not acquired. In children and adolescents, this can be especially frustrating at a crucial stage of their physical and emotional development, which further disrupt social and educational achievements causing concern for patients and their parents. Criteria for pediatric FMS still need to be identified.
Whether the purported bidirectional relationship of these associated somatic conditions can be attributed to shared pathophysiology or common triggers, potentially modifiable risk factors exist for developing FMS – sleep, obesity, stress, nutrition, physical inactivity. The relationship between predisposing environmental factors and genetics fuel further epigenetic studies of this diagnosis as FMS is found at increased prevalence in adult individuals who have experienced specific infections (EBV, Q-fever, hepatitis B, hepatitis C, HIV, mycoplasma), trauma (psychological and physical), and wartime military service2,3.
Surrounding the medical management of fibromyalgia, effective regimens for fibromyalgia included a medication in our cohort. Duloxetine, milnacipran, and pregabalin are FDA approved for fibromyalgia20with duloxetine for use in children as young as 7 years of age21. Use of pregabalin for the treatment of fibromyalgia in pediatrics has not been established, a placebo controlled trial in adolescents as young as 12 years old demonstrated pregabalin to be as safe as its use in adults22. Duloxetine was either not effective or not tolerated in 4 of the 17 patients and they were switched to a tricyclic antidepressant, pregabalin, or milnacipran with better result. Although both duloxetine and milnacipran are both SNRIs, they differ in their reuptake inhibition as duloxetine is more selective for serotonin reuptake and milnacipran for norepinephrine reuptake23. Milnacipran is not currently FDA approved for use in pediatrics24. SNRIs, SSRIs, neuropathic pain agents have a black box warning for increased risk of suicidal thoughts24; families should be made aware of this warning as FMS have high association of comorbid depression.
Due to the wide range of symptomatology and subjectivity, there is a clear need for uniform consistent diagnostics to capture the heterogeneity of expression of FMS so the pathology is not disputed. Major gaps for the utility of this diagnostic criteria in the pediatric population persist. Yet without validated measures for children, clinicians have no alternative. This poses a challenge in optimal management of FMS in a group of individuals with entirely different social, biological, physical, behavioral, developmental, and emotional biospheres than that of the adult.
Improved diagnostics could ideally lead to targeted treatment plans thus decreasing the time to for treatment and improving quality of life.