Muscle Pain and Weakness



Muscle Pain and Weakness


Lawrence J. Kagen




Symptoms of muscle pain (myalgia) and weakness are commonly encountered in clinical medicine. The history to evaluate these problems in affected patients should include not only the site(s), duration, character, and functional limitations but also the family background, medications taken, and other possible comorbid conditions.



ETIOPATHOGENESIS


I. Myalgia and weakness can be considered under several etiologic categories



  • Myopathies. These disorders usually are manifested in proximal musculature and present initially with pain and weakness. Atrophy is generally a late finding. The causes of myopathies are many but an abbreviated list would include:



    • Inflammatory disorders. Dermatomyositis, polymyositis, inclusion body myositis, other connective tissue disorders, especially scleroderma, and Sjögren’s syndrome. Systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), and sarcoidosis may also have myositis as a feature.


    • Endocrinopathies. Many endocrine disorders affect muscles and their function (see Chapter 55). The most commonly encountered are thyroid diseases and diabetes.


    • Electrolyte disturbances. Particularly those involving calcium, magnesium, sodium, and potassium.


    • Medications and toxins. Such as the statin agents, penicillamine, and alcohol. Cocaine use may also lead to myopathy.


    • Genetic diseases. The muscular dystrophies, particularly facioscapular humeral dystrophy, and the distal myopathies in adults should be considered in this category.


    • Metabolic disorders. Genetic abnormalities of carbohydrate and lipid metabolism can produce pain and exercise intolerance.


  • Neurologic disorders



    • Upper motor neuron diseases. Diseases of the brain such as hemorrhage, infarction, infection, or neoplasm may be the cause of weakness and loss of function. Generally, the severity of involvement, its anatomical location, reflex abnormalities, sensory disturbances, and impaired cerebral function will alert the examiner to abnormalities in this area.


    • Spinal nerve root disorders. Spinal stenosis causes muscle aching and heaviness, generally of the lower extremities, on exertion and may mimic symptoms of vascular ischemia.


    • Lower motor neuron disorders. The presence of atrophic, flaccid musculature, with cramps, fasciculations, and loss of deep tendon reflexes characterizes these disorders.


    • Peripheral neuropathies. Neuropathies of this type usually are associated with sensory loss. Weakness, if present, often begins in distal musculature. Atrophy and loss of deep tendon reflexes occur.


    • Myoneural junction disorders. Myasthenic syndromes may appear similar to myopathies in many aspects. Ocular or facial involvement and marked fatigue are important characteristics.


  • Other disorders producing muscle symptoms

Jul 29, 2016 | Posted by in RHEUMATOLOGY | Comments Off on Muscle Pain and Weakness
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