Polymyalgia Rheumatica – A Medical Student Clinical Pearl

Alexis Lamontagne

MD Candidate, Class of 2022

DMNB, Dalhousie University

Case:

A 73 y/o M presents with a 1 week history of proximal muscle aches and stiffness including his hips, shoulders and neck. He describes the stiffness as worse in the morning, recently he has had trouble getting out of bed at all. He finds that the stiffness is relieved and regains function as he begins to move around. He also notes increased stiffness after periods of immobility. It has become progressively worse over the past week which lead to seeking medical help in the emergency department.

There are no other associated symptoms including jaw claudication, headache, weight loss, fevers, chills, night-sweats, vision changes, paresthesias, or preceding cold or illness.

The patient has no significant past medical history. His only regular medication is omeprazole. He does not smoke, consumes 4 alcoholic drinks per day, and uses no other recreational drugs. He lives at home with his wife and they are both retired.

While asking about whether there are any rheumatological conditions that run in the family you learn that his older brother has Polymyalgia Rheumatica (PMR).

Polymyalgia Rheumatica:

The clinical syndrome of PMR should be considered in those aged over 50 presenting with pain and stiffness of the neck, shoulders and hips that is typically worst in the early hours of the morning or on waking, and tends to improve over the course of the day. Inflammatory markers (ESR/CRP) are typically elevated and anaemia may be present due to inflammation. Symptoms of PMR should resolve rapidly with low-dose glucocorticoids.

Differential:

Although weight loss, fever and synovitis/tenosynovitis have all been described in PMR, they should raise suspicion of :

• malignancy,
• deep-seated or disseminated infection (such as endocarditis or osteomyelitis),
• inflammatory arthritides such as rheumatoid arthritis (RA), spondyloarthropathy, or crystal arthropathy.

Investigations:

Bloodwork reveals a normal CBC and an elevated CRP at 108.

Treatment:

Prednisone is initiated at 15mg PO daily. If the initial dose of 15mg does not demonstrate clinical improvement in one week, this can be increased to 20mg or a maximum dose of 25mg.

Once symptoms are controlled for 2 to 4 weeks the dose of prednisone can be tapered. Prednisone can be reduced by 2.5mg every 2 to 4 weeks until 10 mg daily is reached. The dose can then be further tapered by 1 mg per month until cessation or symptoms flare. There is no consensus regarding an optimal tapering regime.

Should a flare occur during the taper, a CRP should be measured and prednisone increased to the lowest dose that relieves symptoms. If a patient relapses several times during the taper, dose reductions can be lengthened to six to eight weeks. If a relapse occurs after the cessation of glucocorticoid use, a CRP should be obtained and prednisone can be initiated at the original dose which managed symptoms.

CRP should be measured again 2 months after the initiation of glucocorticoid therapy and 3 to 6 months thereafter during the course of treatment. Monitoring for symptoms of PMR and Giant Cell Arteritis (GCA) should also take place throughout treatment.

Pathophysiology:

The cause of polymyalgia rheumatica (PMR) is unknown.

The strongest risk factor for PMR is increasing age. It is unheard of in those under 50 years old and incidence increases with each decade, peaking around 75 years. Proposed mechanisms include ageing of the immune system (immunosenescence), ageing of the tissues, and ageing of neurohumoral regulatory systems. Based on the clustering of cases in space and time, it has been proposed that PMR may be triggered by infection. This could lead to persistent inflammation on a background of chronic low-grade inflammation secondary to decline in adaptive immunity and a compensatory increase in innate immune mechanisms. (Mackie 2013)

Relationship to Giant Cell Arteritis:

There is a well-known association between PMR and giant cell arteritis (GCA). Many patients with GCA also have polymyalgic symptoms and some patients with PMR subsequently develop GCA (Mackie 2010). There is some discussion as to whether PMR and GCA are separate disease entities or two conditions on a single pathophysiological spectrum. For the practising clinician it is important to realise that PMR and GCA are treated with different doses of glucocorticoids and that treatment of GCA is a medical emergency, whereas the immediate priority with PMR is to exclude other conditions before starting treatment. All patients with PMR should be assessed for signs and symptoms of GCA at diagnosis and screened for underlying GCA at follow-up visits. These symptoms include constitutional symptoms, headache, jaw claudication, ocular involvement, large vessel involvement, and anemia.

Conclusion:

With a prescription for prednisone, a follow up was arranged with the patient’s family doctor in one week. The patient was advised that the family doctor would taper his prednisone, monitor CRP, and screen for symptoms of PMR and GCA. Additionally, monitoring for the adverse effects of glucocorticoids, including osteoporosis, glucose intolerance, and hypertension would take place.

References:

Mackie SL. Polymyalgia rheumatica: pathogenesis and management. Clin Med (Lond). 2013;13(4):398-400.

Mackie SL. Et al. Can the prognosis of polymyalgia rheumatica be predicted at disease onset? Results from a 5-year prospective study. Rheumatology (Oxford). 2010 Apr; 49(4):716-22.