What is the significance of acuity of symptom onset in the evaluation of myopathies?

Updated: Dec 28, 2017
  • Author: Courtney A Bethel, MD, MPH; Chief Editor: Barry E Brenner, MD, PhD, FACEP  more...
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Acuity of symptom onset aids in diagnosis, as follows:

  • Weakness progressing over hours suggests a toxic etiology or one of episodic paralyses
  • Weakness developing over days suggests acute dermatomyositis or rhabdomyolysis
  • Symptom development over a period of weeks suggests polymyositis, steroid myopathy, or myopathy resulting from endocrine causes (eg, hyperthyroidism, hypothyroidism)

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