Polymyalgia Rheumatica

Sounds like a spell out of Harry Potter, doesn’t it? Polymyalgia Rheumatica! What does it do? It causes muscle pain and stiffness over the body of the wizard that gets hit by it. Such wizard is elderly, likely female, and requires prednisolone (steroid).

So, I had never heard of this condition before this week, but on my Care of the Elderly Placement, I have so far seen three patients with Polymyalgia. One was a lovely chatty lady on ward rounds who was discharged before I got to talk with her, another woman who came into clinic to review her steroid dose because it was giving her Cushingoid features and who implored my partner and I to be the ones to further the research into this condition, and then a man with a history of polymyalgia presenting with hip pain and leg muscle wasting, cause of which was a toss up between arthritic pain or a polymyalgia flare up.


Now the facts.

Definition: Polymyalgia rheumatica (PMR) is an inflammatory rheumatological syndrome that manifests as pain and morning stiffness involving the neck, shoulder girdle, and/or pelvic girdle in individuals older than age 50 years. Peripheral musculoskeletal involvement may also be present.

PMR occurs either as an isolated condition or associated with giant cell arteritis* (GCA).

Aetiology and risk factors: cause unknown (good for me who has to learn it, not so good for patients).

Risk factors: female gender, >50 years, giant cell arteritis

→ ~15% to 20% of patients with PMR have GCA and 40% to 60% of those with GCA have PMR

Epidemiology:

  • Caucasians- highest in Northern Europeans
  • age >50 years
  • more common in women

Signs & Symptoms:

  • sub-acute onset (<2 weeks) of bilateral muscle aching, tenderness and morning stiffness around the neck, shoulders and pelvic girdle
  • objective weakness is uncommon
  • may have: mild polyarthritis, tenosynovitis (inflammation of the synovial sheath surrounding a tendon), carpal tunnel syndrome (10%)
  • may have: fatigue, fever, weight loss, anorexia, depression, malaise

Investigations:

-Diagnosis usually based on clinical findings.

  • ESR (>40 mm/hr) and CRP (non-specific inflammatory markers)- raised (ESR may be normal)

→Note: ESR rises with age and the upper limit is estimated using the Westergren method:

Men: age÷2             Women: (age + 10)÷2 

→Note: CRP normal value = < 10 mg/L

  • Alkaline Phosphatase (ALP) is raised in 30% of cases
  • Ultrasound-commonly show bursitis and joint effusion
  • TSH– to rule out hypothyroidism
  • Full blood count & serum protein electrophoresis– to rule out myeloproliferative disease, usually see normochromic, normocytic anaemia

Management:

  • moderate dose of steroid- Prednisolone (15mg/day, oral)
  • if there is not a dramatic, immediate response (within a few days), consider alternative diagnosis
  • the starting dose is slowly reduced, using ESR and symptoms as a guide
  • steroids are usually needed for over 2 years so gastric (proton pump inhibitor) and bone protection (bisphosphonates, Ca, Vit D) required
  • Methotrexate can be used as a second line treatment

Complications:

  • chronic relapsing PMR
  • complications of long term steroid use: infection risk, osteoporosis, type 2 diabetes, hypertension, cataracts, glaucoma, skin changes (thin and easy bruising), muscle weakness (i.e. steroids suck but sometimes you need them)
  • PMR-related vascular events: cardiovascular, cerebrovascular, peripheral vascular events

Prognosis:

  • response to treatment typically occurs within 24 to 72 hours
  • relapses or symptom exacerbations are common
  • treatment also typically requires 2 to 3 years
  • less commonly, there is a chronic relapsing course that may require a longer course of treatment

References: Cheese & Onion, BMJ Best Practice, Kumar and Clark’s (some sentences are directly copied. Because, let’s face it, I don’t have the medical vocabulary or knowledge to define a condition better than the BMJ).

*Post on Giant Cell Arteritis coming soon to a blog near you

 

 

 

 

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