Muscle Weakness/metabolic|Meds And Other Causes

Etiology

  • Steroid induced: etiology includes long term glucocorticoid use, cushings disease
  • Statin induced: symptoms include vague ache more than weakness; can occur at any time, rarely rhabdomyolysis
  • Other medication/drugs induced muscle breakdown: neuroleptic malignant syndrome, malignant hyperthermia, serotonin syndrome; some drugs of abuse
  • Alcohol induced muscle weakness
  • Trauma induced rhabdomyolysis: This is typically related to significant crush or other injury to muscles, with obvious findings and history (careful exam in those who present w/altered mental status); also with long periods of immobility/lying on the ground (e.g. after syncope or stroke where patient can't move and no help available); compartment syndrome; severe forms of exercise can sometimes precipitate rhabdomyolysis
  • Low phosphorous levels
  • Glycogen storage disorder--> very uncommon

Symptoms

  • May be related to underlying disease
  • Muscular weakness and fatigue
  • As symptoms progress, can have inability to perform ADLs, walk
  • Dysphagia and SOB if muscles of respiration and swallowing affected.

Physical Exam Findings

  • Overt weakness in affected muscles
  • Sensory testing may be normal
  • May have other findings related to underlying process
  • May have atrophy of affected muscles (if long standing)