Fibromyalgia is a chronic pain syndrome causing widespread pain throughout the body in an otherwise seemingly normal individual.
Pathophysiology
Central sensitivity syndrome (CSS) describes a heterogenous group of disorders, including fibromyalgia, IBS, chronic headache, pelvic pain syndromes that all share persistent pain as a prominent feature. These disorders do not arise due to autoimmune, inflammatory or infective causes. It is believed that the pathology behind them relates to the CNS and sensory amplification of pain.
With these disorders, we often see hyperalgesia (increased pain to normally painful stimuli) and/or allodnyia (pain in response to a non-painful stimulus). These indicate issues with CNS processing of pain rather than an abnormality confined to a region of the body. It is also accompanied by other symptoms such as fatigue, memory difficulties, sleep and mood disorders which all indicate a CNS aetiology as well. As a result we can describe it as a central pain amplification disorder.
🔢 Classification
- Primary fibromyalgia - this is the most common form. There is no other cause of pain.
- Secondary fibromyalgia - the fibromyalgia accompanies other painful disorders follow an identifiable event, such as:
- Significant infection - such as Lyme or EBV.
- Injury or physical trauma - such as motor vehicle accident leading to spine injury.
- Emotional stress
- Major surgery
- Peripheral pain syndromes - such has RA or OA.
- Juvenile fibromyalgia - this is less common. It is seen in children and adolescents and disappears after a while but may spontaneously remit.
⚠️ Risk factors
- Female sex - a ratio of 9:1 between females and males.
- Aged 20-50 years old
- Family history
- Rheumatological conditions
😷 Presentation
- Chronic pain - pain is described to be all over the body. It is a must for this to be present to make a diagnosis.
- Diffuse tenderness upon palpation - with absence of systemic disease that may be accountable for this.
- Paraesthesias
- Lethargy and fatigue - similar to that seen in chronic fatigue syndrome.
- Cognitive impairment - labelled fibro fog.
- Insomnia
- Headaches
- Dizziness
- Stiffness
- Sensitivity to sensory stimuli - such a bright lights, odours and noises.
🔍 Investigations
The diagnosis is strictly clinical based on a set of criteria set by the American College of Rheumatology (2010). If the patient does not meet these criteria, then we need to perform other tests to support an alternative diagnosis.
The criteria is known as the Widespread Pain Index (WPI) as well as the Symptom Severity Scale (SSS):
- The WPI takes into account 19 areas on the body where the individual has experienced pain in the preceding week.
- The SSS rates the severity of an individuals fatigue, unrefreshed waking, cognitive symptoms and general somatic symptoms on a scale from 0-3 to get a score out of 12.
Using this criteria we can make a diagnosis when the following 3 are met:
- (WPI >7 and SSS >5) OR (WPI 3-6 and SSS >9)
- Symptoms present for at least 3 months
- No other disorder may explain the pain
🧰 Management
There is no cure for fibromyalgia and the management needs to be tailored towards each patient individually.
We should combine non-pharmacological treatments alongside pharmacological treatments:
- Patient education - explanation of the disease is important and needs to be done.
- Exercise therapy - aerobic exercise is the most effective treatment for fibromyalgia.
- CBT and mindfulness based stress reduction
- Symptomatic management - such as stress, anxiety and panic or addressing sleep disorders.
- 🥇 TCAs - amitryptaline.
- 🥇 SNRIs - duloxetine. Especially if there is concomitant depression.
- 🥇Pregabalin, gabapentin
Often patients may benefit from multiple drug classes while some patients respond to monotherapy.
⚠️ Opiates and NSAIDs should be avoided for long-term use.