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Weakness - Overview

Alternative Names

Lack of strength; Muscle weakness

Definition of Weakness:

Weakness is a reduction in the strength of one or more muscles.

Considerations:

Weakness may be generalized (total body weakness) or localized to only one area, side of the body, limb, or muscle. Weakness is more notable when it is localized. Localized weakness may follow a stroke, flare up of multiple sclerosis, or injury to a nerve.

Weakness may be subjective or objective.

Subjective means you feel weak, but there is no measurable loss of strength.
Objective means there is a measurable loss of strength noted during a physical exam.

A subjective feeling of weakness may be associated with infectious diseases such as mono and the flu.

Common Causes:

Measurable weakness may result from a variety of conditions including metabolic, neurologic, primary muscular diseases, and toxic disorders.

METABOLIC

Addison's disease
Hyperparathyroidism
Low sodium or potassium
Thyrotoxicosis

NEUROLOGIC

Amyotrophic lateral sclerosis
Bell's palsy
Cerebral palsy
Guillain-Barre syndrome
Multiple sclerosis
Pinched nerve (for example, caused by a slipped disk in the spine)
Stroke

PRIMARY MUSCULAR DISEASES

Becker muscular dystrophy
Dermatomyositis
Muscular dystrophy (Duchenne)
Myotonic dystrophy

TOXIC

Botulism
Organophosphate poisoning (insecticides, nerve gas)
Paralytic shellfish poisoning

OTHER

Reviewed last on: 7/17/2007
Robert Hurd, MD, Professor of Endocrinology, Department of Biology, Xavier University, Cincinnati, OH, and physician in the Primary Care Clinic, Cincinnati Veterans Administration Medical Center, Cincinnati, Ohio. Review provided by VeriMed Healthcare Network.

References

Olney RK. Weakness, Disorders of Movement, and Imbalance. In Kasper DL, Braunwald E, Anthony S. Fauci AS, eds. Harrison’s Internal Medicine. 16th ed. New York, NY: McGraw-Hill; 2005.

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