Polymyalgia rheumatica occurs more commonly in older persons and preferentially affects the proximal muscles with markedly elevated measures of inflammation (erythrocyte sedimentation rate [ESR] and C reactive protein [CRP]) and normal muscle enzymes.2 Patients with hypothyroidism may have elevated creatine kinase (CK) and complain of fatigue. A thyroid profile should be completed in all patients with muscle complaints. Patients with neuromuscular disorders, such as myasthenia gravis, will have normal muscle enzymes with muscle weakness and fatigue later in the day or with prolonged exertion and characteristic patterns on EMG/NCS study.2

Malignancies may initially present with muscle weakness and elevated muscle enzymes. Age and gender-specific cancer screening should be completed or updated in those with a myopathic process.9,10 Patients with idiopathic inflammatory myopathies may have other underlying connective tissue disorders such as scleroderma, anti-synthetase syndrome, or mixed connective tissue disorder that will need to be ruled out when referred to rheumatology.5

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It should be understood that benign elevations in muscle enzymes occur. The “normal” values for CK and aldolase are a reference range. There will be outliers that do not signal pathology. Patients with larger muscle mass or those who engage in a regular or strenuous fitness routine may have higher muscle enzymes. A history of use of muscle building supplements should be assessed for, as they can affect muscle enzymes.

Treatment

Given the autoimmune nature of these diseases, treatment consists of immunosuppression. Initial treatment is almost always prednisone, typically 60 mg daily to start.11 A second immunomodulator is then added and often titrated over weeks to months and serves as a steroid-sparing agent, allowing the steroid to be slowly tapered over time.5,11 Clinicians caring for these patients, in any setting, need to be aware of potential side effects and risks associated with treatment. Concomitant immune deficiencies (HIV) and other underlying infections (hepatitis C) need to be ruled out prior to initiating treatment. Treatment with a steroid can contribute to the development of diabetes, osteoporosis, cataracts, hypertension, obesity, and fragile skin.

Patients should be taught about signs and symptoms of hyperglycemia, and if they are diabetic, primary care providers need to work with rheumatology to adequately control the patients’ elevated blood sugars and similarly be alert for potential hypoglycemia during the tapering of steroids. Vitamin D should be checked and repleted if necessary and regular calcium/vitamin D initiated, along with a bisphosphonate, if not contraindicated. If possible, patients should have vaccinations prior to immunosuppression (ie, influenza, pneumococcal polysaccharide vaccine, shingles). Immunosuppressed patients need to be monitored for infection. The type of immunomodulator will dictate regular toxicity monitoring.

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Conclusion

Clinicians in all settings are in a position to identify patients with potential myopathic processes and complete an initial diagnostic work-up. In this patient’s case, the initial work-up was in progress when an emergency referral to rheumatology was made. Her evaluation continued, and a treatment plan was outlined and then modified as her clinical condition dictated. The patient in this case was markedly debilitated at her initial presentation to rheumatology. Early identification of these patients has the potential to reduce morbidity and excess disability.

Kathleen Walter, ANP-BC, is affiliated with the Pittsburgh VA Health Care System, Department of Rheumatology.

References

  1. Hoogendijk JE, Amato AA, Lecky BR, Choy EH, Lundberg IE, Rose MR, et al. 119th ENMC international workshop: trial design in adult idiopathic inflammatory myopathies, with the exception of inclusion body myositis, 10-12 October 2003, Naarden, The Netherlands. Neuromuscul Disord. 2004;14:337-345.
  2. Khan S, Christopher-Stine L. Polymyositis, dermatomyositis, and autoimmune necrotizing myopathy: clinical features. Rheum Dis Clin North Am. 2011;37:143-158.
  3. Wortman RL. Idiopathic inflammatory myopathies: Clinical features. In: Klippel JH, et al, eds. Primer on the rheumatic diseases. 13th ed. New York, NY: Springer; 2008:363-366.
  4. Stenzel W, Goebel HH, Aronica E. Review: Immune-mediated necrotizing myopathies—a heterogeneous group of diseases with specific myopathological features. Neuropathol Appl Neurobiol. 2012;38:632-646.
  5. Liang C, Needham M. Necrotizing autoimmune myopathy. Curr Opin Rheumatol. 2011;23:612-619.
  6. Ellis E, Ann Tan J, Lester S, Tucker G, Blumbergs P, Roberts-Thomson P, et al. Necrotizing myopathy: clinicoserologic associations. Muscle Nerve. 2012;45:189-194.
  7. Rider LG, Miller FW. Idiopathic inflammatory myopathies: Pathology and pathogenesis. In: Klippel JH, et al, eds. Primer on the rheumatic diseases. 13th ed. New York, NY: Springer; 2008:368-374.
  8. Baer AN. Metabolic myopathies. In: Klippel JH, et al, eds. Primer on the rheumatic diseases. 13th ed. New York, NY: Springer; 2008:381-388.
  9. Baer AN. Paraneoplastic muscle disease. Rheum Dis Clin North Am. 2011;37:185-200.
  10. Vu HJ, Pham D, Makary R, Nguyen T, Shuja, S. Paraneoplatic necrotizing myopathy presenting as severe muscle weakness in a patient with small-cell lung cancer: successful response to chemoradiation therapy. Clin Adv Hematol Oncol. 2011;9: 557-560.
  11. Oddis CV. Idiopathic inflammatory myopathies: Treatment and assessment. In: Klippel JH, et al, eds. Primer on the rheumatic diseases. 13th ed. New York, NY: Springer; 2008:375-380.

From the July 01, 2017 Issue of Clinical Advisor

Topics:

Neurology