Polymyositis Clinical Presentation

Updated: Nov 22, 2016
  • Author: Ramesh Pappu, MD, DPH, MBBS; Chief Editor: Herbert S Diamond, MD  more...
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Presentation

History

Symptoms of polymyositis gradually develop over a period of 3-6 months. Diagnosis is usually delayed, because, unlike in dermatomyositis, no associated rash occurs before the onset of muscle disease. Family history and medication history are important in excluding other causes of myopathy.

The history of patients with polymyositis or dermatomyositis typically includes the following:

  • Symmetrical, proximal muscle weakness with insidious onset
  • Muscles usually painless (Myalgias occur in fewer than 30% of patients.)
  • Dysphagia (30%) and aspiration, if pharyngeal and esophageal muscles are involved
  • Arthralgias may be associated
  • Difficulty kneeling, climbing or descending stairs, stepping onto a curb, raising arms, lifting objects, combing hair, and arising from a seated position
  • Weak neck extensors cause difficulty holding the head up
  • Involvement of pelvic girdle usually greater than upper body weakness
  • Cardiac involvement may cause symptoms of pericarditis or cardiomyopathy
  • Characteristic rash of face, trunk, and hands seen in dermatomyositis only

Muscular manifestations

Patients with polymyositis usually present with symmetrical, proximal muscle weakness in the upper and lower extremities. Weakness of neck flexors also occurs. Patients with polymyositis may report muscle pain and tenderness, which may be confused with symptoms of polymyalgia rheumatica. The disease may exist for several months before the patient seeks medical advice, and all of the muscles of the thighs, trunk, shoulders, hips, and upper arms are usually involved. Muscle weakness may fluctuate from week to week or from month to month.

Fine motor movements that depend on the strength of distal muscles, such as buttoning a shirt, sewing, knitting, or writing, are affected only late in the disease.

Dysphagia secondary to oropharyngeal and esophageal involvement occurs in about one third of patients with polymyositis and is a poor prognostic sign. Dysphonia is also a poor prognostic sign but is much less common.

Ocular muscles are never involved in generalized polymyositis. However, isolated orbital myositis, an inflammatory disorder involving the extraocular muscles, is well described. Facial and bulbar muscle weakness is extremely rare in individuals with polymyositis.

A family history of neuromuscular disease, endocrinopathy, or exposure to myotoxic drugs or toxins is absent.

Constitutional manifestations

Polymyositis is a systemic disease. Symptoms may include the following:

  • Morning stiffness
  • Fatigue
  • Anorexia
  • Fever (associated with antisynthetase antibodies such as anti-Jo-1)
  • Weight loss

Pulmonary manifestations

Pharyngeal and esophageal weakness may lead to aspiration pneumonia. Patients with polymyositis may experience exertional dyspnea secondary to weakness of chest wall muscles and diaphragmatic muscles. Patients receiving immunosuppressants are at an increased risk of infection.

Interstitial lung disease occurs in 5-30% of patients with idiopathic inflammatory myopathy (associated with antisynthetase antibodies, especially anti-Jo-1). Patients may be asymptomatic or present with exertional dyspnea, cough, and fever. [14]

Interstitial pneumonitis, bronchiolitis obliterans organizing pneumonia, and pulmonary capillaritis have been described in conjunction with polymyositis.

Cardiac manifestations

Cardiac involvement is unusual and, if present, portends a bad prognosis. Rhythm disturbances, conduction defects, congestive heart failure, pericarditis, pulmonary hypertension, and myocarditis can occur.

Joint involvement

Patients can present with arthralgias or arthritis. Arthritis is usually symmetrical and involves the knees, wrists, and hands (associated with antisynthetase antibodies). A severe, deforming arthropathy without erosions has been reported; erosive changes are very rare.

Overlap syndromes

Polymyositis has been associated with other connective-tissue diseases, including the following:

  • Systemic lupus erythematosus
  • Rheumatoid arthritis
  • Mixed connective-tissue disease
  • Sjögren syndrome
  • Scleroderma

About 25% of patients with scleroderma have myositis; this phenomenon has been associated with anti-PM/Scl (anti-PM-1) antibody. In Japan, anti-Ku antibody has been described with this condition.

Gastrointestinal manifestations

Symptoms may include the following:

  • Dysphagia
  • Odynophagia
  • Nasal regurgitation
  • Reflux esophagitis
  • Abdominal bloating
  • Constipation

Renal manifestations

Intrinsic renal disease is rare in patients with polymyositis. Occasionally, severe rhabdomyolysis with myoglobinuria can result in acute tubular necrosis.

Cutaneous manifestations

Unlike in dermatomyositis, rash is absent in polymyositis. However, "mechanic's hands" (associated with antisynthetase antibodies), ie, hyperkeratotic eruptions over the finger pads and lateral aspects of the fingers, have been reported.

Raynaud phenomenon has been described in patients with antisynthetase antibodies. Rarely, periorbital edema may occur (best described in dermatomyositis). Calcinosis occurs in approximately 5% of patients with polymyositis (in association with sclerodermalike illness). Telangiectasias are uncommon.

Inclusion body myositis

This condition is a slowly progressive, idiopathic, inflammatory myopathy that mostly affects men older than age 50 years. Muscle involvement predominantly includes proximal muscles but may also include distal muscles (50%), and involvement may be asymmetrical. Dysphagia is found in most patients (60%).

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Physical Examination

Nothing is characteristic about the muscle weakness in polymyositis. It is not painful, although a minority of patients report aches or cramps. On occasion, the muscle may be sore to palpation and may have a nodular and grainy feel.

Sensory examination findings are normal. Ocular muscles remain normal even in advanced, untreated cases. Facial muscles remain normal except in rare advanced cases.

The pharyngeal and neck flexor muscles are often involved, causing dysphagia and difficulty in holding up the head. When the patient is first seen, many of the muscles of the trunk, shoulders, hips, upper arms, and thighs are usually involved. In restricted forms of the disease, only the neck or paraspinal muscles (camptocormia) are affected. [15]

In advanced cases and rarely in acute cases, respiratory muscles are affected. Severe weakness is almost always associated with muscular wasting. Dysphonia with nasal speech may be noted. Lung examination findings may include evidence of interstitial lung disease, such as dry inspiratory crackles in the lung bases ("Velcro").

The tendon reflexes are preserved, but they may be absent in severely weakened or atrophied muscles.

Primary cardiac abnormalities due to myocarditis may be present in a few patients. These abnormalities mainly manifest as atrioventricular conduction defects, tachyarrhythmias, low ejection fraction, dilated cardiomyopathy, or congestive heart failure.

General systemic disturbances, such as fever, malaise, weight loss, arthralgia, and Raynaud phenomenon, may occur when polymyositis is associated with a connective-tissue disorder.

Inclusion body myositis

Inclusion body myositis manifests as severe, proximal muscle weakness with atrophy, often with distal muscle weakness. The weakness may be asymmetrical. Deep tendon reflexes may be impaired or absent if weakness is severe.

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