Polymyalgia rheumatica and fibromyalgia

01Definition and overview

Polymyalgia rheumatica

Polymyalgia rheumatica (PMR) is an inflammatory condition of people aged 50 and over that causes pain and stiffness of the shoulder and hip girdles and the neck, with a raised acute-phase response. Despite its name ("pain in many muscles"), the muscles are not inflamed: the inflammation lies in the bursae, tendon sheaths and joints around the shoulders and hips. It belongs with giant cell arteritis to one spectrum of disease: the two share age, genes and immunology, and can occur together. The one thing to remember: PMR is a diagnosis made only after the mimics have been considered, because steroids will make many other illnesses look better for a while.

Fibromyalgia

Fibromyalgia is a syndrome of chronic widespread pain, fatigue, unrefreshing sleep and cognitive difficulties, without inflammation or damage of the tissues that hurt. The pain arises from altered pain processing in the nervous system, a type of pain now called nociplastic. It is the commonest cause of chronic widespread pain and overlaps with other central sensitivity syndromes: irritable bowel syndrome, tension headache, temporomandibular pain, chronic pelvic pain and chronic fatigue syndrome.

02Etiology and pathophysiology

Polymyalgia rheumatica

The cause is unknown. Age is the main risk factor, and PMR is commonest in people of northern European descent, with links to HLA-DRB1*04, as in giant cell arteritis. The immune system of the ageing artery and synovium is involved: activated dendritic cells, T cells and macrophages, and above all IL-6, which is high in the blood and falls with treatment, and which drives the acute-phase response, the fatigue and the stiffness. Ultrasound and MRI show subacromial and subdeltoid bursitis, biceps tenosynovitis, glenohumeral and hip synovitis, trochanteric bursitis and inflammation between the spinous processes of the neck and lumbar spine.

Ultrasound of the arteries shows that about a fifth of patients with apparently pure PMR have a halo in the temporal, axillary or other large arteries, a subclinical vasculitis, which may be linked to more relapses. Cancer immunotherapy with immune checkpoint inhibitors can also cause a PMR-like illness.

Fibromyalgia

1. 1

   A susceptible person

   Women, people with a family history (the risk is several times higher in first-degree relatives), and those with early adversity, psychological distress, poor sleep or other chronic pain are at higher risk.
2. 2

   A trigger

   Physical trauma, an infection, a period of stress or an inflammatory disease often precedes it, though many patients name none.
3. 3

   Central sensitisation

   The spinal cord and brain amplify pain signals. Excitatory transmitters such as glutamate and substance P are higher in the cerebrospinal fluid, and the descending pathways that normally damp pain, using serotonin and noradrenaline, are weak. Functional imaging shows larger responses of the pain-processing areas to the same stimulus.
4. 4

   Widespread symptoms

   Normal pressure hurts (allodynia) and painful stimuli hurt more (hyperalgesia). Disrupted deep sleep, low activity and low mood feed the pain in a vicious circle.

The muscles are normal. A subset of patients has reduced small nerve fibres in skin biopsies, whose meaning is debated. Fibromyalgia is common in inflammatory and autoimmune disease: it affects up to a fifth or more of patients with rheumatoid arthritis, lupus and spondyloarthritis.

03Clinical features

Polymyalgia rheumatica

• Pain and stiffness of both shoulders and upper arms, in nearly all, and of the neck, hips, thighs and buttocks in most, usually starting over days to a few weeks.
• Morning stiffness lasting more than 45 minutes, often hours, and stiffness after rest (gelling); patients struggle to get out of bed, rise from a chair, dress, comb their hair or turn over in bed.
• Systemic features in about a third: fatigue, low-grade fever, weight loss, low mood and loss of appetite.
• Peripheral arthritis in about a quarter, usually knees or wrists, and carpal tunnel syndrome; swelling of the hands with pitting oedema is seen in some.
• On examination, active movement of the shoulders and hips is limited by pain, but strength is normal when tested carefully, unlike in myositis.

Fibromyalgia

• Widespread pain, often described as aching, burning or exhausting, that moves around and is present most days for at least three months.
• Fatigue and unrefreshing sleep in almost all; cognitive difficulties ("fibro fog") with poor memory and concentration.
• Stiffness, a feeling of swollen hands without swelling, paraesthesia, headaches, irritable bowel symptoms, painful periods, an irritable bladder, and sensitivity to cold, noise and bright light.
• Anxiety and depression in a third to a half.
• On examination, nothing but widespread tenderness: no synovitis, no weakness, no neurological signs.

04Diagnosis and management

Polymyalgia rheumatica: diagnosis

There is no diagnostic test; the diagnosis is clinical, supported by a raised ESR or CRP, after the mimics have been excluded. PMR without a raised ESR or CRP is unusual, and the diagnosis is then questioned. Tests before starting steroids:

• ESR and CRP, full blood count (a normocytic anaemia, raised platelets), kidney and liver function (alkaline phosphatase is often raised), calcium and bone profile, glucose or HbA1c;
• protein electrophoresis and serum free light chains for myeloma, TSH, creatine kinase, vitamin D;
• rheumatoid factor and anti-CCP antibodies, and ANA if a connective tissue disease is possible;
• urine dipstick, and a chest X-ray if there are systemic features;
• ultrasound of the shoulders and hips in atypical cases, and PET-CT when large-vessel vasculitis or cancer is suspected.

The 2012 EULAR/ACR classification criteria require age 50 or over, aching of both shoulders and a raised CRP or ESR, then score:

They classify; they do not replace the search for mimics:

Polymyalgia rheumatica: treatment

1. 1

   Confirm, then treat

   Glucocorticoids are started once the diagnosis is reasonably secure, not as a diagnostic trial; specialist referral is advised for atypical features, uncertainty or a poor response.
2. 2

   Starting dose

   Oral prednisolone 12.5 to 25 mg a day as a single morning dose (European guidance of 2025 says 15 to 25 mg; UK guidance of 2026 starts at 12.5 to 15 mg, rising to 25 mg if needed). Intramuscular methylprednisolone is an alternative.
3. 3

   Check the response

   Most patients improve by at least 70 per cent within a week, and the ESR and CRP normalise within about four weeks. A poor response means the diagnosis must be reconsidered, not the dose simply raised.
4. 4

   Taper

   Once controlled for 2 to 4 weeks, down to 10 mg a day within 1 to 2 months, then by 1 mg every 4 to 8 weeks, aiming to stop within about a year; faster in patients at high risk of steroid harm.
5. 5

   Relapse

   Return to the last effective dose for 2 to 4 weeks and taper more slowly. Relapse is judged by symptoms with the CRP, not by a raised CRP alone.

Steroid-sparing drugs are added for patients who relapse, who cannot taper, or who are at high risk of steroid harm (diabetes, osteoporosis, glaucoma, heart failure, mental illness):

• methotrexate, 7.5 to 10 mg weekly in most trials and sometimes more, which reduces relapses and the total steroid dose, and can be considered early; it is used off label;
• sarilumab, an IL-6 receptor antibody, 200 mg under the skin every two weeks, licensed in the EU for PMR that responds inadequately to glucocorticoids or relapses during tapering; in a trial, 28 per cent reached sustained remission at a year against 10 per cent on steroids alone, with less than half the steroid dose; tocilizumab is used off licence. IL-6 blockade suppresses the CRP, so relapse and new giant cell arteritis must be judged clinically. In the UK sarilumab is not yet funded by the NHS for PMR;
• not NSAIDs, which do not control PMR and harm older patients, except briefly for pain from another cause.

Bone protection for all: almost every patient needs at least 7.5 mg of prednisolone for three months, so calcium and vitamin D, and in UK guidance a bisphosphonate from the start unless contraindicated. Exercise, blood pressure, glucose, weight and eyes are monitored, and patients carry a steroid card and know not to stop suddenly.

Fibromyalgia: diagnosis

The diagnosis is positive, made from the history, not by excluding everything else. The 2016 revision of the ACR criteria requires all of:

1. A Widespread Pain Index (WPI, the number of 19 body areas painful in the past week) of 7 or more with a Symptom Severity Scale (SSS) score of 5 or more, or a WPI of 4 to 6 with an SSS of 9 or more. The SSS adds the severity of fatigue, unrefreshing sleep and cognitive symptoms (0 to 3 each) to the presence of headaches, lower abdominal pain or cramps and depression in the past six months (1 each), giving 0 to 12.
2. Generalised pain, in at least 4 of 5 body regions.
3. Symptoms at a similar level for at least three months.
4. A diagnosis of fibromyalgia is valid whatever other diagnoses are present.

The older 1990 criteria needed pain in at least 11 of 18 tender points pressed with about 4 kg of force. Tender points are no longer needed: the count was rarely done well in practice, its cut-off was arbitrary, it missed the fatigue, sleep and cognitive symptoms that matter to patients, and it under-diagnosed men. Fibromyalgia is now seen as the severe end of a continuum of widespread pain and distress.

Tests are kept few: a full blood count, ESR or CRP, TSH, creatine kinase, calcium and vitamin D, liver and kidney function, and others only if the history suggests a disease. Autoantibodies such as ANA are not tested routinely, because low-titre positives are common in healthy people and mislead.

Fibromyalgia: management

The aims are to improve function and quality of life, not to remove all pain. The European recommendations of 2017 start with a prompt diagnosis and a clear explanation: the pain is real, it comes from how the nervous system processes signals, it does not damage the joints or muscles and it does not lead to disability in a wheelchair.

Drugs help a minority, by a modest amount, and are reviewed and stopped if they do not work. No medicine has a European licence for fibromyalgia: the EMA turned down pregabalin, duloxetine and milnacipran for it around 2009 and 2010, although all three are approved for it in the United States, so in Europe they are used off label. Pregabalin carries a risk of misuse and dependence. Strong opioids and corticosteroids are not used: opioids add dependence and opioid-induced hyperalgesia without benefit, and steroids treat an inflammation that is not there.

05Epidemiology

Polymyalgia rheumatica

PMR is one of the commonest inflammatory rheumatic diseases of older people, with an incidence of roughly 50 to over 100 per 100,000 people over 50 each year, highest in northern Europe. The lifetime risk is about 2.4 per cent in women and 1.7 per cent in men. It is rare before 50, and the mean age at onset is around 70 to 75; women are affected two to three times as often. Clinically evident giant cell arteritis occurs in roughly 5 to 20 per cent of patients with PMR, depending on how it is sought (UK guidance quotes 5 to 10 per cent developing it later), ultrasound finds subclinical vasculitis in about a fifth, and about half of those with giant cell arteritis have PMR.

Fibromyalgia

Fibromyalgia affects about 1 to 4 per cent of adults, depending on the criteria used; a 2026 meta-analysis put it at 1 to 2 per cent of the world's population. With modern criteria women are affected two to three times as often as men (the old tender-point criteria made it nine times). It is commonest between 30 and 60 and more common with low income, in people with other chronic pain, and in inflammatory and autoimmune diseases.

06Prognosis

Polymyalgia rheumatica

PMR runs a self-limiting course in most patients, but slowly: most need glucocorticoids for one to two years, and a quarter or more for longer. About half relapse during tapering, more often women and those with a high ESR at diagnosis or peripheral arthritis, and possibly those with subclinical vasculitis. The main harm comes from the treatment: fractures, diabetes, cataract, infection and weight gain, which is why bone protection and steroid-sparing drugs matter. Life expectancy is normal. Patients are followed for the features of giant cell arteritis throughout, and for a cancer or another diagnosis if the course is atypical.

Fibromyalgia

Fibromyalgia is chronic, with symptoms that fluctuate but seldom disappear. It does not shorten life or damage the joints, but it is a major cause of disability and lost work. The outlook is better with early diagnosis, an active approach with exercise and self-management, and treatment of depression and sleep problems; it is worse with long sick leave, passive treatments, repeated investigations and opioids.