Muscle weakness classification
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Vishnu Vardhan Serla M.B.B.S. [2]
Classification
True vs. Perceived
The term subsumes two other more specific terms, true weakness and perceived weakness.
- True weakness (or "objective weakness") describes a condition where the instantaneous force exerted by the muscles is less than would be expected. For instance, if a patient suffers from amyotrophic lateral sclerosis (ALS), motor neurons are damaged and can no longer stimulate the muscles to exert normal force.
- Perceived weakness (or "subjective weakness") describes a condition where it seems to the patient that more effort than normal is required to exert a given amount of force.[1] For instance, in some people with chronic fatigue syndrome (CFS) who may struggle to climb a set of stairs when feeling especially fatigued, their muscle strength when objectively measured (eg, the maximum weight they can press with their legs) is essentially normal, though this is not true for CFS patients who may be disabled through post-exertional weakness/malaise etc. and in severe cases may not be able to climb a flight of stairs.
In some conditions, such as myasthenia gravis muscle strength is normal when resting, but true weakness occurs after the muscle has been subjected to exercise. This is also true for some cases of CFS, where objective post-exertion muscle weakness with delayed recovery time has been measured and is a feature of some of the published definitions. [2][3][4][5][6][7]
In addition to true/perceived, muscle weaknes can also be central, neural and peripheral. Central muscle weakness manifests as an overall, bodily or systemic, sense of energy deprivation, and peripheral weakness manifests as a local, muscle-specific incapacity to do work. [8][9] Neural weakness can be both central and peripheral.
References
- ↑ Enoka RM, Stuart DG (1992). "Neurobiology of muscle fatigue". J. Appl. Physiol. 72 (5): 1631–48. PMID 1601767.
- ↑ Paul L, Wood L, Behan WM, Maclaren WM; Demonstration of delayed recovery from fatiguing exercise in chronic fatigue syndrome. European Journal of Neurology 1999 Jan;6(1):63-69 PMID: 10209352
- ↑ McCully K K, Natelson B H; Impaired oxygen delivery to muscle in chronic fatigue syndrome. Clinical Science 1999:97:603-608
- ↑ Pascale De Becker, PhD; Johan Roeykens, PT; Masha Reynders, PT; Neil McGregor, MD, PhD; Exercise Capacity in Chronic Fatigue Syndrome. Archives of Internal Medicine Vol. 160 No. 21, November 27, 2000
- ↑ De Becker P, McGregor N, De Meirleir K. A definition-based analysis of symptoms in a large cohort of patients with chronic fatigue syndrome. J Intern Med 2001;250:234-240.
- ↑ Bruce M Carruthers, Anil Kumar Jain, Kenny L De Meirleir, Daniel L Peterson, Nancy G Klimas et al, Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: Clinical Working Case Definition, Diagnostic and Treatment Guidelines, A Consensus Document Journal of Chronic Fatigue Syndrome 11(1):7-115, 2003. ISBN 0-7890-227-9
- ↑ Jammes Y, Steinberg JG, Mambrini O, Bregeon F, Delliaux S; Chronic fatigue syndrome: assessment of increased oxidative stress and altered muscle excitability in response to incremental exercise. J Intern Med., 2005 Mar;257(3):299-310.
- ↑ Gandevia SC, Enoka RM, McComas AJ, Stuart DG, Thomas CK (1995). "Neurobiology of muscle fatigue. Advances and issues". Adv. Exp. Med. Biol. 384: 515–25. PMID 8585476.
- ↑ Kent-Braun JA (1999). "Central and peripheral contributions to muscle fatigue in humans during sustained maximal effort". European journal of applied physiology and occupational physiology. 80 (1): 57–63. PMID 10367724.