Detecting Toxic Myopathies as Medication Side Effect

Toxic exposures are important etiologies to consider in all patients with myopathy because these conditions are often reversible with prompt treatment or removal of the offending agent. Medication combinations can also lead to myotoxicity and myopathy. It is important to distinguish between muscle disease secondary to illness (ie, autoimmune, inflammatory, or infectious cause) and muscle weakness secondary to the toxicity from medications. It is for this reason that it is imperative that the clinician is able to elicit a thorough history and physical examination on these patients. Electro-diagnostic studies play an important role in excluding competing diagnoses, confirming a suspected clinical diagnosis of myopathy, and occasionally providing clues for categories of myopathy based on the presence or absence of abnormal spontaneous activity. An understanding of the utility and limitation of the diagnostic tests available will help narrow the differential diagnosis and potentially confirm a specific etiology of muscle disease.