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Muscle Atrophy (Muscle Wasting)

A weakening, shrinking, and loss of muscle caused by disease or lack of use.

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(Source: NIH - National Cancer Institute)

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Evidence reviews

Drug treatment for spinal muscular atrophy types II and III

Spinal muscular atrophy (SMA) is a neuromuscular disorder that results in progressive muscle weakness with onset in childhood and adolescence. There are three main types of SMA. Drug treatment for SMA type I is discussed in a separate Cochrane review. This review is of drug treatment for SMA types II and III. Both of these reviews were first published in 2009 and are now updated. The age of onset of SMA type II is between six and 18 months. Children with SMA type II will never be able to walk without support; they survive beyond two years and may live into adolescence or longer. The age of onset of SMA III, also known as Kugelberg‐Welander disease, is after 18 months. Children with SMA type III develop the ability to walk at some time and their life expectancy is normal. From six randomised controlled trials, there is no evidence for a significant effect on the disease course when patients with SMA types II and III are treated with creatine (55 participants), phenylbutyrate (107 participants), gabapentin (84 participants), thyrotropin releasing hormone (9 participants), hydroxyurea (57 participants) or combination therapy with valproate and acetyl‐L‐carnitine (61 participants). The risk of bias of the included trials was systematically analysed and none of the studies were completely free of bias. Thus, there is still no known efficacious drug treatment for SMA types II and III.

Drug treatment for spinal muscular atrophy type I

Spinal muscular atrophy (SMA) is a severe neuromuscular disease with onset in childhood and adolescence that results in progressive muscle weakness. There are three main types of SMA. Drug treatment for SMA types II and III is discussed in a separate Cochrane review. The age of onset of SMA type I, also known as Werdnig‐Hoffmann disease, is before six months. Children with SMA type I will never be able to sit without support and usually die by the age of two years. It is one of the most important causes of death due to a genetic disease in childhood. There was only one small randomised trial in the original review, which assessed the efficacy of riluzole for 10 children with SMA type I. In this trial all three children in the placebo group died, but three of the seven children treated with riluzole were still alive at the ages of 30, 48 and 64 months. However, none of the children in the riluzole or placebo group developed the ability to roll, sit or stand. For several reasons the overall quality of the study was low, mainly because the study was too small to detect an effect and there were baseline differences that resulted in risk of bias. Evidence is insufficient to recommend riluzole for SMA type I. No further trials were identified for this 2011 update. No drug treatment has been shown to have significant efficacy for SMA type I.

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Summaries for consumers

Drug treatment for spinal muscular atrophy types II and III

Spinal muscular atrophy (SMA) is a neuromuscular disorder that results in progressive muscle weakness with onset in childhood and adolescence. There are three main types of SMA. Drug treatment for SMA type I is discussed in a separate Cochrane review. This review is of drug treatment for SMA types II and III. Both of these reviews were first published in 2009 and are now updated. The age of onset of SMA type II is between six and 18 months. Children with SMA type II will never be able to walk without support; they survive beyond two years and may live into adolescence or longer. The age of onset of SMA III, also known as Kugelberg‐Welander disease, is after 18 months. Children with SMA type III develop the ability to walk at some time and their life expectancy is normal. From six randomised controlled trials, there is no evidence for a significant effect on the disease course when patients with SMA types II and III are treated with creatine (55 participants), phenylbutyrate (107 participants), gabapentin (84 participants), thyrotropin releasing hormone (9 participants), hydroxyurea (57 participants) or combination therapy with valproate and acetyl‐L‐carnitine (61 participants). The risk of bias of the included trials was systematically analysed and none of the studies were completely free of bias. Thus, there is still no known efficacious drug treatment for SMA types II and III.

Drug treatment for spinal muscular atrophy type I

Spinal muscular atrophy (SMA) is a severe neuromuscular disease with onset in childhood and adolescence that results in progressive muscle weakness. There are three main types of SMA. Drug treatment for SMA types II and III is discussed in a separate Cochrane review. The age of onset of SMA type I, also known as Werdnig‐Hoffmann disease, is before six months. Children with SMA type I will never be able to sit without support and usually die by the age of two years. It is one of the most important causes of death due to a genetic disease in childhood. There was only one small randomised trial in the original review, which assessed the efficacy of riluzole for 10 children with SMA type I. In this trial all three children in the placebo group died, but three of the seven children treated with riluzole were still alive at the ages of 30, 48 and 64 months. However, none of the children in the riluzole or placebo group developed the ability to roll, sit or stand. For several reasons the overall quality of the study was low, mainly because the study was too small to detect an effect and there were baseline differences that resulted in risk of bias. Evidence is insufficient to recommend riluzole for SMA type I. No further trials were identified for this 2011 update. No drug treatment has been shown to have significant efficacy for SMA type I.

Strength training or comprehensive aerobic exercise training for muscle disease

Strength training, which is performed to improve muscle strength and muscle endurance, or aerobic exercise programmes, which are designed to improve cardiorespiratory endurance, might optimise physical fitness and prevent additional muscle wasting in people with muscle disease. However, people with muscle disease and some clinicians are still afraid of overuse and have a cautious approach to training. This updated review (most recent date of search 2 July 2012) included two eligible trials of strength training in people with facioscapulohumeral muscular dystrophy (FSHD) and myotonic dystrophy (101 participants), two trials of strength training combined with aerobic exercise in people with mitochondrial myopathy (18 participants) and myotonic dystrophy type I (35 participants) and one trial of aerobic exercise in people with polymyositis and dermatomyositis (14 participants). These trials showed that moderate‐intensity strength training in people with myotonic dystrophy or with FSHD, and aerobic exercise training in people with dermatomyositis or polymyositis appear not to harm muscles. Strength training combined with aerobic exercise appears to be safe in myotonic dystrophy type I and may be effective in increasing endurance in people with mitochondrial myopathy. Evidence suggests that strength training is not harmful in people in FSHD, myotonic dystrophy, mitochondrial disorders and dermatomyositis and polymyositis, but further research is needed to determine potential benefit.

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More about Muscle Atrophy

Photo of an adult

Also called: Muscular atrophy, Muscle wasting disorder, Amyotrophia, Amyotrophy

Other terms to know:
Atrophy, Muscles

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