What should be the focus of history in the evaluation of suspected myopathies?

Updated: Dec 28, 2017
  • Author: Courtney A Bethel, MD, MPH; Chief Editor: Barry E Brenner, MD, PhD, FACEP  more...
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Answer

Obtain the family history to determine presence of periodic paralysis or muscular dystrophy. Personal history of autoimmune disease, endocrinopathy, renal insufficiency, and/or alcoholism should be noted.

Discuss any previous episodes of severe weakness, particularly any that occurred after exercise or exposure to cold temperatures, which may indicate one of the periodic paralyses. Some patients with familial hypokalemic periodic paralysis may note that the symptoms occur after eating high-carbohydrate meals.

History of medication use is very important. Steroids, lipid-lowering agents, [8] retroviral agents, alcohol, colchicine, pentachlorophenol (PCP), heroin, and a myriad of other medications may cause myopathies. In some cases, the combination of multiple myopathic agents is responsible for the acute deterioration. [9]

Occupational and travel history may lead a physician to consider ingestion of barium chloride or carbonate as a cause for acute hypokalemic paralysis. Note the following:

  • These are absorbable salts (in contrast to nonabsorbable, safe, widely used barium sulfate) that may contaminate table salt or flour; absorbable salts may be used industrially for glazing pottery
  • Paralysis results when passive efflux of potassium is blocked at the cell membrane and elevated intracellular potassium decreases the resting membrane potential

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