Approach to the patient with muscle weakness
- Marc L Miller, MD
Marc L Miller, MD
- Clinical Assistant Professor of Medicine
- Tufts University School of Medicine
- Section Editors
- Ira N Targoff, MD
Ira N Targoff, MD
- Section Editor — Muscle Disease
- Professor of Medicine
- University of Oklahoma Health Sciences Center
- Jeremy M Shefner, MD, PhD
Jeremy M Shefner, MD, PhD
- Section Editor — Neuromuscular Disease
- Professor and Chair of Neurology, Barrow Neurological Institute
- Professor of Neurology, University of Arizona, Phoenix
- Clinical Professor of Neurology, Creighton University
The evaluation of the patient presenting with a complaint of “weakness” involves three steps:
●Distinguishing true muscle weakness from asthenia or motor impairment not due to loss of muscle power
●Localizing, within the neuromuscular system, the site of the lesion that is producing weakness
●Determining the cause of the lesion
This topic will review the approach to the patient with muscle weakness by addressing these three issues. The specific tests used to assess muscle weakness are discussed separately, as are the clinical manifestations and evaluation of respiratory muscle weakness. (See "Muscle examination in the evaluation of weakness" and "Respiratory muscle weakness due to neuromuscular disease: Clinical manifestations and evaluation".)
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- DISTINGUISHING TRUE MUSCLE WEAKNESS FROM ASTHENIA
- Physical examination
- LOCALIZING THE SITE OF THE LESION
- Distribution of weakness as a guide to localizing the lesion
- DETERMINING THE CAUSE OF THE LESION
- Sites of lesions
- - Lesions of upper motor neurons
- - Anterior horn cell lesions
- - Lesions of the peripheral nervous system
- - Myopathy
- Clinical investigations
- - Laboratory studies
- - Electrophysiologic studies
- - Magnetic resonance imaging
- - Muscle biopsy
- - Genetic testing
- RESPIRATORY MUSCLE WEAKNESS