Effect of intramuscular depot betamethasone injection in patients with fibromyalgia and elevated C-reactive protein levels

Correspondence to Professor George Habib, Rheumatology Clinic, Nazareth Hospital, Azrieli Faculty of Medicine, Bar-Ilan University, Safed, 16000 Nazareth, Israel; [email protected]

Introduction

Fibromyalgia is a type of chronic pain syndrome.¹ It is characterized by diffuse musculoskeletal pain and fatigue.² Other common symptoms and signs include peripheral numbness, tenderness to touch, memory and mood problems and sleep disturbances.³ The prevalence of fibromyalgia is about 3%–5% on average in the general population, mostly women with a female:male ratio of ~4:1.⁴ The pathogenesis of this syndrome is not fully understood. Central localization of the pain is the leading theory, where the presumption is that pain perception at the brain level is exaggerated.⁵ Classically, patients with fibromyalgia have negative or normal serological markers.⁶ Fibromyalgia is considered in the differential diagnosis of symmetrical musculoskeletal pain and could be misdiagnosed in favor of rheumatoid arthritis (RA) or ankylosing spondylitis (AS), especially among patients with elevated inflammatory measures or patients with positive rheumatoid factor.^{7 8}

Fibromyalgia is treated mainly symptomatically with different modalities, mainly medications including tricyclics, benzodiazepines, simple analgesic, duloxetine, pregabalin, non-steroidal anti-inflammatory drugs (NSAIDs), mild opiates, strong opiates, selective serotonin reuptake inhibitors (SSRIs), and/or medical cannabis.⁹ Many of the patients are also treated with local injection of corticosteroids mainly at epicondyle areas, at rotator cuff areas or great trochanteric area, where pain and tenderness at these areas could be part of this syndrome. Some patients with fibromyalgia report pain relief following systemic treatment of corticosteroids, when seronegative arthritis was suspected initially, and ruled out later (personal experience).

There are nearly no data in the literature about systemic corticosteroid treatment in fibromyalgia.

In this prospective study, we wanted to evaluate a single intramuscular injection of depot betamethasone (betamethasone dipropionate+betamethasone sodium phosphate) (Diprospan) on patients with fibromyalgia with unexplained elevated inflammatory measures.

Materials and methods

Patients with the diagnosis of fibromyalgia according to the American College of Rheumatology criteria,¹⁰ who were followed at the outpatient rheumatology clinics and failed at least simple analgesic, tricyclic antidepressants (if not contraindicated), simple opiates and pregabalin/duloxetine, with unexplained elevated C-reactive protein (CRP) levels higher than twice the maximal upper limits (measured at least twice over 3 months), were asked to participate in our study. These patients were...