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Polymyalgia Rheumatica

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Overview

Polymyalgia rheumatica (PMR) is an inflammatory rheumatological condition of unknown aetiology characterised by severe bilateral pain and morning stiffness of the shoulder, neck, and pelvic girdle. PMR is very closely associated with giant cell arteritis (temporal arteritis).

Epidemiology

  • PMR is usually seen in people >50 years or above and the mean age of onset is 73
  • Women are more frequently affected by men

Risk Factors & Associations

  • Age of 50 years or more
  • Giant cell arteritis
  • Female sex

Presentation

Symptoms usually emerge subacutely (<1 month):

  • Aching morning stiffness in proximal limb muscles:
    • Morning stiffness in the shoulder girdle/pelvic girdle for >1 hour
    • Inflammatory-type pain in the shoulder girdle/pelvic girdle for >1 hour in the morning
  • No true limb weakness
    • Patients may report weakness but this is due to the pain and stiffness
  • Rapidly responds to corticosteroids
  • Other non-specific symptoms:

Differential Diagnoses

Rheumatoid arthritis (RA)

  • PMR and the early stages of RA present similarly
  • PMR has a prompt response to steroids, whereas RA doesn’t respond as drastically
  • RA would have elevated rheumatoid factor (RF) and possibly positive anti-CCP

Giant cell arteritis (GCA)

  • Patients would have features of GCA including unilateral headache, jaw claudication, scalp tenderness and ocular involvement (painless loss of vision)

Fibromyalgia

  • The pain is more widespread and there is no associated shoulder/hip girdle stiffness
  • Features do not respond as drastically to corticosteroid use
  • ESR and CRP are normal in fibromyalgia

Polymyositis/dermatomyositis

  • These have symmetrical weakness of the shoulder and pelvic girdles
  • Weakness is not present in PMR
  • Muscle enzymes such as creatine kinase are raised in polymyositis/dermatomyositis but are normal in PMR as there is no muscle inflammation and damage in PMR

Bursitis/tendonitis

  • No systemic symptoms are present
  • Usually singular joints are  affected, such as unilateral shoulder involvement
  • ESR is normal

Investigations

To diagnose PMR, other conditions possibly causing the symptoms must be ruled out. Initial investigations include:

  • Erythrocyte sedimentation rate (ESR):
    • Elevated
  • C-reactive protein (CRP):
    • Elevated
  • Creatine kinase (CK):
    • Normal, not elevated in PMR
  • FBC, U&Es, LFTs, TFTs, bone profile, rheumatoid factor, urinalysis, urine/serum protein electrophoresis
    • Some myeloproliferative diseases can mimic PMR

Management

Patients drastically improve with corticosteroid use. If they fail to do so, an alternative diagnosis must be considered.

  • 1st line: prednisolone
    • Can be taken daily until symptoms resolve and ESR/CRP normalise, then be tapered off slowly
  • Calcium + vitamin D + bisphosphonates e.g. alendronic acid + cholecalciferol + calcium carbonate
    • Patients taking long-term steroids must be offered bone protection

Monitoring

  • Follow patients monthly with:
    • Evaluation of scalp tenderness
    • Evaluation of temporal artery tenderness
    • Peripheral joint manifestations
    • ESR and/or CRP levels
  • Once patients are being tapered off, follow-up visits can be extended to 3 months

Relapses of PMR

  • Relapse is the recurrence of the symptoms of PMR or onset of giant cell arteritis, not just the raised ESR or CRP alone
  • They are managed with steroids and immunosuppressive therapy is considered after two relapses

Patient Advice

  • Patients should be educated on the symptoms of giant cell arteritis and when to seek medical help

Complications

  • Chronic relapsing PMR
  • Complications related to corticosteroid use

Prognosis

  • The risk of giant cell arteritis happening while PMR is being treated is around 15%
  • The prognosis varies, people usually need treatment for 1-2 years
  • Relapse is common but responds to restarting or increasing the dose of systemic steroids

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