Becker's muscular dystrophy: Difference between revisions
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Early clinical features include calf hypertrophy, difficulty rising from a chair, [[Anatomical terms of location|proximal]] muscle [[Muscle weakness|weakness]], climbing stairs, sustaining [[Imbalance|balance]], elevating arms, and in later stages [[heart failure]].<ref name="pmid20301298" /> | Early clinical features include calf hypertrophy, difficulty rising from a chair, [[Anatomical terms of location|proximal]] muscle [[Muscle weakness|weakness]], climbing stairs, sustaining [[Imbalance|balance]], elevating arms, and in later stages [[heart failure]].<ref name="pmid20301298" /> | ||
The most common complications in Becker's muscular dystrophy are [[Cardiac failure|cardiac]] and [[Respiratory failure|respiratory]] failure, [[Pneumonia|pneumonias]], and in rare cases [[cognitive impairment]]. | The most common complications in Becker's muscular dystrophy are [[Cardiac failure|cardiac]] and [[Respiratory failure|respiratory]] failure, [[Pneumonia|pneumonias]], and in rare cases [[cognitive impairment]]. | ||
[[Prognosis]] is generally poor, depending on [[spectrum]] of Becker's muscular dystrophy, but much better that [[Duchenne muscular dystrophy]]. | [[Prognosis]] is generally poor, depending on [[spectrum]] of Becker's muscular dystrophy, but much better that [[Duchenne muscular dystrophy]]. In 2002, the [[Survival analysis|survival]] rate at age 20 was 60%. | ||
If left [[untreated]], the majority of patients with Becker's muscular dystrophy may die due to [[Cardiac failure|cardiac]] and [[Respiratory failure|respiratory]] failure in their mid-40's. | If left [[untreated]], the majority of patients with Becker's muscular dystrophy may die due to [[Cardiac failure|cardiac]] and [[Respiratory failure|respiratory]] failure in their mid-40's. | ||
Cradiac, respiratory, and orthopedic care has greatly improved in last years for patients with Becker disease, this, increasing the life span in these individuals.<ref name=":4" / | Cradiac, respiratory, and orthopedic care has greatly improved in last years for patients with Becker disease, this, increasing the life span in these individuals.<ref name=":4" /> | ||
<br /> | <br /> | ||
== Diagnosis == | == Diagnosis == | ||
The diagnosis of Becker's muscular dystrophy is made with a classic clinical presentation plus elevated [[Creatine kinase|CK]], [[Molecular genetic analysis|molecular genetic testing]], or [[muscle biopsy]]. | The diagnosis of Becker's muscular dystrophy is made with a classic clinical presentation plus elevated [[Creatine kinase|CK]], [[Molecular genetic analysis|molecular genetic testing]], or [[muscle biopsy]]. | ||
=== Symptoms === | === Symptoms === | ||
| Line 109: | Line 109: | ||
* [[Anatomical terms of location|Proximal]] [[muscle weakness]] | * [[Anatomical terms of location|Proximal]] [[muscle weakness]] | ||
* [[Myalgia|Myalgias]] | * [[Myalgia|Myalgias]] | ||
* [[Cramp|Muscle cramps]] | * [[Cramp|Muscle cramps]] | ||
* [[Imbalance]] | * [[Imbalance]] | ||
* [[Toe walking]] | * [[Toe walking]] | ||
| Line 116: | Line 116: | ||
* Difficulty [[climbing]] stairs | * Difficulty [[climbing]] stairs | ||
* Difficulty raising the arms | * Difficulty raising the arms | ||
* [[Cardiac failure|Heart failure]] | * [[Cardiac failure|Heart failure]] | ||
* [[Dyspnea]] | * [[Dyspnea]] | ||
| Line 135: | Line 135: | ||
* Elevated [[Alanine transaminase|ALT]]/[[ASTL|AST]]<ref name=":5" /> | * Elevated [[Alanine transaminase|ALT]]/[[ASTL|AST]]<ref name=":5" /> | ||
* [[Myoglobinuria]] when strenous [[Physical exercise|physical activity]]<ref name=":5" /> | * [[Myoglobinuria]] when strenous [[Physical exercise|physical activity]]<ref name=":5" /> | ||
* Normal [[Gamma-glutamyl transpeptidase|GGT]] | * Normal [[Gamma-glutamyl transpeptidase|GGT]] | ||
=== Hystopathology === | === Hystopathology === | ||
| Line 146: | Line 146: | ||
=== EMG === | === EMG === | ||
[[Electromyography|EMG]] in Becker's muscular [[dystrophy]], may reveal myopathic [[motor units]] with or without [[muscle membrane]] instability.<ref name=" | [[Electromyography|EMG]] in Becker's muscular [[dystrophy]], may reveal myopathic [[motor units]] with or without [[muscle membrane]] instability. | ||
=== Echocardiography === | |||
[[Echocardiography|Echocardiogram]] should be done at the time of diagnosis.<ref name="pmid2030129817">{{cite journal| author=Adam MP, Ardinger HH, Pagon RA, Wallace SE, Bean LJH, Stephens K | display-authors=etal| title=GeneReviews® | journal= | year= 1993 | volume= | issue= | pages= | pmid=20301298 | doi= | pmc= | url= }}</ref> | |||
=== Imaging Findings === | === Imaging Findings === | ||
There are no [[X-ray]] findings characteristic with with Becker's muscular dystrophy, but [[scoliosis]] may be found. | There are no [[X-ray]] findings characteristic with with Becker's muscular dystrophy, but [[scoliosis]] may be found. | ||
<br /> | <br /> | ||
== Treatment | == Treatment == | ||
=== Medical Therapy === | |||
There is no definitive treatment for Becker's muscular [[dystrophy]]; treatment will be [[Multidisciplinary care|multidisciplinary]] depending on [[Comorbidity|comorbidities]]; the mainstay of therapy is [[supportive care]]. | |||
Corticosteroids have shown to improve strength in other dystrophinopathies, but its efficacy on Beckers muscular dystrophy is uncertain.<ref name="pmid2030129812">{{cite journal| author=Adam MP, Ardinger HH, Pagon RA, Wallace SE, Bean LJH, Stephens K | display-authors=etal| title=GeneReviews® | journal= | year= 1993 | volume= | issue= | pages= | pmid=20301298 | doi= | pmc= | url= }}</ref> | |||
The management of [[Scoliosis (patient information)|scoliosis]] is bracing and [[surgery]] in some cases.<ref name="pmid2030129813">{{cite journal| author=Adam MP, Ardinger HH, Pagon RA, Wallace SE, Bean LJH, Stephens K | display-authors=etal| title=GeneReviews® | journal= | year= 1993 | volume= | issue= | pages= | pmid=20301298 | doi= | pmc= | url= }}</ref> | |||
[[Beta-blockers]], [[ARBs|angiotensin II-receptor blockers]], and [[ACE inhibitor|ACE inhibitors]] are used to improve [[ventricular function]] in patients with Becker's muscular [[dystrophy]] when EF is less than 55%.<ref name="pmid203012984">{{cite journal| author=Adam MP, Ardinger HH, Pagon RA, Wallace SE, Bean LJH, Stephens K | display-authors=etal| title=GeneReviews® | journal= | year= 1993 | volume= | issue= | pages= | pmid=20301298 | doi= | pmc= | url= }}</ref> | |||
Physical | [[Physical exercise|Low impact exercise]] (eg. [[swimming]]) should be advised. If [[myalgia]] presents, [[Physical exercise|physical activity]] should be reduced and [[myoglobinuria]] cheked out.<ref name="pmid2030129814">{{cite journal| author=Adam MP, Ardinger HH, Pagon RA, Wallace SE, Bean LJH, Stephens K | display-authors=etal| title=GeneReviews® | journal= | year= 1993 | volume= | issue= | pages= | pmid=20301298 | doi= | pmc= | url= }}</ref> | ||
=== Surgery === | |||
[[Heart transplantation|Cardiac transplantation]] may be requiered in patients with severe [[Dilated cardiomyopathy classification|dilated cardiomyopathy]].<ref name="pmid2030129811">{{cite journal| author=Adam MP, Ardinger HH, Pagon RA, Wallace SE, Bean LJH, Stephens K | display-authors=etal| title=GeneReviews® | journal= | year= 1993 | volume= | issue= | pages= | pmid=20301298 | doi= | pmc= | url= }}</ref> | |||
< | Severe or incapacitating [[scoliosis]] may be corrected with [[surgery]].<ref name="pmid2030129810">{{cite journal| author=Adam MP, Ardinger HH, Pagon RA, Wallace SE, Bean LJH, Stephens K | display-authors=etal| title=GeneReviews® | journal= | year= 1993 | volume= | issue= | pages= | pmid=20301298 | doi= | pmc= | url= }}</ref> | ||
=== | |||
=== Prevention[edit | edit source] === | === Prevention[edit | edit source] === | ||
| Line 190: | Line 180: | ||
* Once diagnosed and successfully treated, patients with [disease name] are followed-up every [duration]. Follow-up testing includes [test 1], [test 2], and [test 3]. | * Once diagnosed and successfully treated, patients with [disease name] are followed-up every [duration]. Follow-up testing includes [test 1], [test 2], and [test 3]. | ||
Appropriate management of individuals with a dystrophinopathy can prolong survival and improve quality of life. | Appropriate management of individuals with a dystrophinopathy can prolong survival and improve quality of life.<ref name="pmid2030129815">{{cite journal| author=Adam MP, Ardinger HH, Pagon RA, Wallace SE, Bean LJH, Stephens K | display-authors=etal| title=GeneReviews® | journal= | year= 1993 | volume= | issue= | pages= | pmid=20301298 | doi= | pmc= | url= }}</ref> | ||
Annual or biannual evaluation by a cardiologist beginning at the time of diagnosis; monitoring for scoliosis; baseline pulmonary function testing before wheelchair dependence; frequent evaluations by a pediatric pulmonologist. For heterozygous females: cardiac evaluation at least once after the teenage years.<ref name="pmid2030129816">{{cite journal| author=Adam MP, Ardinger HH, Pagon RA, Wallace SE, Bean LJH, Stephens K | display-authors=etal| title=GeneReviews® | journal= | year= 1993 | volume= | issue= | pages= | pmid=20301298 | doi= | pmc= | url= }}</ref> | |||
''Prevention of secondary complications:'' Evaluation by a pulmonologist and cardiologist before surgeries; pneumococcal and influenza immunizations annually; nutrition assessment; physical therapy to promote mobility and prevent contractures; sunshine and a balanced diet rich in vitamin D and calcium to improve bone density and reduce the risk of fractures; weight control to avoid obesity. | ''Prevention of secondary complications:'' Evaluation by a pulmonologist and cardiologist before surgeries; pneumococcal and influenza immunizations annually; nutrition assessment; physical therapy to promote mobility and prevent contractures; sunshine and a balanced diet rich in vitamin D and calcium to improve bone density and reduce the risk of fractures; weight control to avoid obesity. | ||
Revision as of 20:08, 29 May 2020
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Moises Romo, M.D.
Overview
Former "pseudohypertrophic muscular dystrophy", now Becker's muscular dystrophy, is a genetic neuromuscular condition characterized by slowly progresive weakness and atrophy of skeletal (mostly legs and pelvis) and cardiac muscles.
Historical Perspective
Becker's muscular dystrophy was first described by Peter Emil Becker, a German neurologist, psychiatrist and geneticist, in 1953 with his thesis called ‘‘Dystrophia Musculorum Progessiva: A Genetic and Clinical Investigation of the Muscular Dystrophies’’, after his work was interrumpted in 1942 due to WWII recruitment.
Before Becker, in the 1860's, French neurologist Guillaume Benjamin Amand Duchenne described in detail a slowly progessive muscular weakness in a boy, later known as Duchenne muscular dystrophy.
The association between genetic mutations and Duchenne muscular dystrophy was made in 1986.
In 1987, dystrophin gene on X chromosome were first implicated in the pathogenesis of Becker's muscular dystrophy.
Pathophysiology
The pathogenesis of Becker's muscular dystrophy is characterized by muscle weakness and pseudohypertrophy (mostly proximal), cardiomyopathy, elevated CK and skelletal deformities.
Becker's muscular dystrophy is inherited in an X-linked recessive fashion.
Becker's muscular dystrophy is caused by a mutation in the gene DMD, one of the largest genes in humans. This gene encodes for the 3685Y aminoacid protein called dystrophin, wich can be found in skeletal and cardiac muscle, among other tisues. This mutation produces a truncated dystrophin protein that will translate into a decreased but not incomplete functionality (difference from Duchenne). Around 33% of patients with Becker's muscular dystrophy have de novo mutations. Point mutations and duplications appear mostly from spermatogenesis while deletions arise from oogenesis in most of te cases.
On microscopic histopathological analysis, endomysial fibrosis with fatty replacement of muscle in later stages, inflammation, increased internal nuclei, myofiber cleavage with necrosis, and phagocytosis are characteristic findings of Becker's muscular dystrophy.[1]
Clinical Features
Unlike Duchenne muscular dystrophy, Becker's muscular dystrophy (BMD) phenotype presents at a later age, widely variable onset from early childhood to late adulthood, most of them falling in puberty range. Most of the patients will requiere a wheelchair after age 16.
Clinical presentation Becker's muscular dystrophy include:
- Progressive symmetric muscle weakness, with a predilection in proximal muscles (eg. pelvic, legs, shoulders)[2]
- Congestive heart failure
- Calf hypertrophy[2]
- Cramping and muscle pain after exercise[2]
- Flexion contractures[2]
- Normal neck flexor muscle strength (differenting factor of BMD from DMD)[2]
There is an abcense of fasciculations, and this finding may exclude BMD[2]
CNS is rarely afected in Becker's muscular dystrophy, for this reason, intelligence is usually spared.
Most of women are asymptomatic carriers, with very rare cases presenting the classic symptoms.
Differentiating Becker's muscular dystrophy from other Diseases
Becker's muscular dystrophy must be differentiated from other diseases that cause skelletal and cardiac muscle afection, such as:
- Duchenne muscular dystrophy. Presents with most of the symptoms of Beckers muscular dystrophy but with an earlier and more severe onset, most of them having symptoms from age 3 (Gower's sign); by convention, if a patient with a suspected dystrophinopathy stops walking before 12 years of age, he has DMD. Another diferentiating factor is the normal strength of neck flexor muscles in BMD[2]
- Limb-girdle muscular dystrophy (LGMD). Is a group of inherited autosomal conditions that are clinically similar to dystrophynopathies (muscle weakness and wasting) but occur in both sexes. They are caused by a gene mutation that encodes sarcoglycans.
- Emery-Dreifuss muscular dystrophy (EDMD). Is a neuromuscular disorder that may be inherited in an autosomal or X-linked mode. The classic clinical triad encompasses incidious muscle weakness and wasting with predilection in the humero-peroneal distribution, joint contractures in childhood, and cardiac afection that includes palpitations, and syncope.
- Spinal muscular atrophy (SMA). Presents with muscle atrophy, delayed weight and height gain, restrictive lung disease, scoliosis, joint contractures, and sleep difficulties. Is inherited in an autosomal recessive mode.[3]
- Dilated cardiomyopathy (DCM). Familial variants may be inherited in an autosomal (dominant or recessive), or an X-linked fashion. Presents with symptoms of dyspnea and poor exercise tolerance.
- Barth syndrome. Is an X-linked disorder characterized by prepubertal growth delay followed by a growth spurt, muscle weakness, cardiomyopathy, neutropenia, and facial gestalt.
Screening
Prenatal molecular genetic testing is recomended in couples planning to conceive and have family members who are afected by or are carriers of a dystrophinopathy.
In-utero fetal muscle biopsy has also been realized under couples request for fetuses with a high probability of beign affected and inconclusive genetic linkage.
It is important to identify females at risk to be heterozygous of a dystrophinopathy, in order to manage possible cardiac complications; this can be done by molecular genetic testing, CK measurements, and linkage analysis.
Epidemiology and Demographics
The prevalence of Becker's muscular dystrophy is approximately 1-3 per 100,000 individuals.
The incidence of Becker's muscular dystrophy is approximately 3-6 per 100,000 male births worldwide.[4][5]
Age
Becker's muscular dystrophy is diagnosed in 85% of patients by age 25.
Gender
Becker's muscular dystrophy affects mostly men, women are carriers almost exclusively (except rare situation).
Race
Becker's muscular dystrophy usually affects individuals of the hispanic race.[6]
Asian individuals are less likely to develop Becker's muscular dystrophy.[7]
Risk Factors
Becker's muscular dystrophy is developed in the majority of cases from males who are born from genetic carrier mothers or by spontaneous mutation,[8] there has not been any risk factors implicated for a DMD gene mutation.
Studies have found that several genetic polymorphisms and mutations may be a factor for Becker's muscular dystrophy progression, but further research is necessary to draw conclusions.
Natural History, Complications and Prognosis
The majority of patients with Becker's muscular dystrophy remain asymptomatic until adolescence.
Early clinical features include calf hypertrophy, difficulty rising from a chair, proximal muscle weakness, climbing stairs, sustaining balance, elevating arms, and in later stages heart failure.[9]
The most common complications in Becker's muscular dystrophy are cardiac and respiratory failure, pneumonias, and in rare cases cognitive impairment.
Prognosis is generally poor, depending on spectrum of Becker's muscular dystrophy, but much better that Duchenne muscular dystrophy. In 2002, the survival rate at age 20 was 60%.
If left untreated, the majority of patients with Becker's muscular dystrophy may die due to cardiac and respiratory failure in their mid-40's.
Cradiac, respiratory, and orthopedic care has greatly improved in last years for patients with Becker disease, this, increasing the life span in these individuals.[10]
Diagnosis
The diagnosis of Becker's muscular dystrophy is made with a classic clinical presentation plus elevated CK, molecular genetic testing, or muscle biopsy.
Symptoms
Symptoms of Becker's muscular dystrophy may include the following:
- Proximal muscle weakness
- Myalgias
- Muscle cramps
- Imbalance
- Toe walking
- Difficulty raising from a chair
- Difficulty climbing stairs
- Difficulty raising the arms
- Heart failure
- Dyspnea
Physical Examination
Patients with Becker's muscular dystrophy usually adapt a posture with shoulders held back, abdomen stuck out, and lumbar hyperlordosis.
Physical examination may be remarkable for:
Laboratory Findings
An elevated CK is typical in Becker's muscular dystrophy, with a peak around 10-15 years of age.[11]
Other laboratory finding consistent with Becker's muscular dystrophy may be:
- Elevated ALT/AST[11]
- Myoglobinuria when strenous physical activity[11]
- Normal GGT
Hystopathology
Histologic findings in Becker's muscular may be:
- Atrophic small myofibers[11]
- Muscle fibers necrosis and regeneration[11]
- Endomysial fibrosis and fatty replacement of muscle[11]
- Inflammation[11]
EMG
EMG in Becker's muscular dystrophy, may reveal myopathic motor units with or without muscle membrane instability.
Echocardiography
Echocardiogram should be done at the time of diagnosis.[12]
Imaging Findings
There are no X-ray findings characteristic with with Becker's muscular dystrophy, but scoliosis may be found.
Treatment
Medical Therapy
There is no definitive treatment for Becker's muscular dystrophy; treatment will be multidisciplinary depending on comorbidities; the mainstay of therapy is supportive care.
Corticosteroids have shown to improve strength in other dystrophinopathies, but its efficacy on Beckers muscular dystrophy is uncertain.[13]
The management of scoliosis is bracing and surgery in some cases.[14]
Beta-blockers, angiotensin II-receptor blockers, and ACE inhibitors are used to improve ventricular function in patients with Becker's muscular dystrophy when EF is less than 55%.[15]
Low impact exercise (eg. swimming) should be advised. If myalgia presents, physical activity should be reduced and myoglobinuria cheked out.[16]
Surgery
Cardiac transplantation may be requiered in patients with severe dilated cardiomyopathy.[17]
Severe or incapacitating scoliosis may be corrected with surgery.[18]
Prevention[edit | edit source]
- There are no primary preventive measures available for [disease name].
- Effective measures for the primary prevention of [disease name] include [measure1], [measure2], and [measure3].
- Once diagnosed and successfully treated, patients with [disease name] are followed-up every [duration]. Follow-up testing includes [test 1], [test 2], and [test 3].
Appropriate management of individuals with a dystrophinopathy can prolong survival and improve quality of life.[19]
Annual or biannual evaluation by a cardiologist beginning at the time of diagnosis; monitoring for scoliosis; baseline pulmonary function testing before wheelchair dependence; frequent evaluations by a pediatric pulmonologist. For heterozygous females: cardiac evaluation at least once after the teenage years.[20] Prevention of secondary complications: Evaluation by a pulmonologist and cardiologist before surgeries; pneumococcal and influenza immunizations annually; nutrition assessment; physical therapy to promote mobility and prevent contractures; sunshine and a balanced diet rich in vitamin D and calcium to improve bone density and reduce the risk of fractures; weight control to avoid obesity.
Cardiomyopathy. Recommendations are based on an American Academy of Pediatrics policy statement and various additional publications [American Academy of Pediatrics Section on Cardiology and Cardiac Surgery 2005, Jefferies et al 2005, Viollet et al 2012] and apply to patients with the DMD or BMD phenotype.
- The authors' institution commonly treats children with DMD or BMD early with an ACE inhibitor and/or beta blocker.
- When used in combination, these appear to lead to initial improvement of left ventricular function; however, ACE inhibitors are also used without beta blockers, with similar results [Viollet et al 2012].
- The optimal time to start treatment in DMD is unknown, but most cardiologists will initiate treatment when the left ventricle ejection fraction drops below 55% and fractional shortening is less than 28% [Jefferies et al 2005, Viollet et al 2012].
- Angiotensin II-receptor blockers (ARBs) such as losartan are similarly effective and can be used in cases of poor tolerability of ACE inhibitors [Allen et al 2013].
- In cases of overt heart failure, other heart failure therapies including diuretics and digoxin are used as needed.
- Cardiac transplantation is offered to persons with severe dilated cardiomyopathy and BMD with limited or no clinical evidence of skeletal muscle disease.
Scoliosis treatment as needed is appropriate. The management of scoliosis involves bracing and surgery. Most patients end up getting a spinal fusion. The use of rods is not contraindicated; therefore, rod and bone grafts are used to fuse the spine. A minority of patients do not develop significant scoliosis and may not require a spinal fusion.
Corticosteroid therapy. Studies have shown that corticosteroids improve the muscle strength and function of individuals with DMD (see Corticosteroid Therapy in DMD). This therapy remains the treatment of choice for affected individuals between ages five and 15 years. Corticosteroid therapy is not recommended in children before age two years [Bushby et al 2010a]. This treatment is also used in BMD, although the efficacy is less clear (see BMD below).
The following published recommendations for corticosteroid therapy are in accordance with the national practice parameters developed by the American Academy of Neurology and the Child Neurology Society [Moxley et al 2005] (full text), as well as the DMD Care Considerations Working Group [Bushby et al 2010a].
- Boys with DMD should be offered treatment with prednisone (0.75 mg/kg/day, maximum daily dose: 30-40 mg) or deflazacort (0.9 mg/kg/day, maximum daily dose: 36-39 mg) as soon as plateauing or decline in motor skills is noted, which usually occurs at age 4-8 years. Prior to the initiation of therapy, the potential benefits and risks of corticosteroid treatment should be carefully discussed with each individual.
- To assess benefits of corticosteroid therapy, the following parameters are useful: timed muscle function tests, pulmonary function tests, and age at loss of independent ambulation.
- To assess risks of corticosteroid therapy, maintain awareness of the potential corticosteroid therapy side effects (e.g., weight gain, cushingoid appearance, short stature, decrease in linear growth, acne, excessive hair growth, gastrointestinal symptoms, behavioral changes). There is also an increased frequency of vertebral and long bone fractures with prolonged corticosteroid use [King et al 2007].
- The optimal maintenance dose of prednisone (0.75 mg/kg/day) or deflazacort (0.9 mg/kg/day) should be continued if side effects are not severe. Significant but less robust improvement can be seen with gradual tapering of prednisone to as low as 0.3 mg/kg/day (or ~0.4 mg/kg/day of deflazacort).
- If excessive weight gain occurs (>20% over estimated normal weight for height over a 12-month period), the prednisone dose should be decreased by 25%-33% and reassessed in a few months. If excessive weight gain continues, the dose should be further decreased by an additional 25% to the minimum effective dose cited above after three to four months.
- If significant weight gain or intolerable behavioral side effects occur in patients treated with prednisone, change to deflazacort on a ten-day-on / ten-day-off schedule or a high-dose weekend schedule. In patients on deflazacort, side effects of asymptomatic cataracts and weight gain should be monitored.
BMD. Information about the efficacy of prednisone in treating individuals with BMD is limited. Many clinicians continue treatment with glucocorticoids after loss of ambulation for the purpose of maintaining upper limb strength, delaying the progressive decline of respiratory and cardiac function, and decreasing the risk of scoliosis. Retrospective data suggest that the progression of scoliosis can be reduced by long-term daily corticosteroid treatment; however, an increased risk for vertebral and lower-limb fractures has been documented [King et al 2007]. Men on steroid therapy were less likely to require spinal surgery [Dooley et al 2010b]. The dose is allowed to drift down to 0.3-0.6 mg/kg/day of prednisone or deflazacort, which is still effective [Bushby et al 2010a].
References
{{Reflist|2}}
Template:Muscular Dystrophy it:Distrofia muscolare di Becker nl:Becker spierdystrofie no:Beckers muskeldystrofi fi:Beckerin lihasdystrofia
- ↑ Invalid
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<ref>tag; no text was provided for refs named:5 - ↑ Adam MP, Ardinger HH, Pagon RA, Wallace SE, Bean LJH, Stephens K; et al. (1993). "GeneReviews®". PMID 20301298.
- ↑ Adam MP, Ardinger HH, Pagon RA, Wallace SE, Bean LJH, Stephens K; et al. (1993). "GeneReviews®". PMID 20301298.
- ↑ Adam MP, Ardinger HH, Pagon RA, Wallace SE, Bean LJH, Stephens K; et al. (1993). "GeneReviews®". PMID 20301298.
- ↑ Adam MP, Ardinger HH, Pagon RA, Wallace SE, Bean LJH, Stephens K; et al. (1993). "GeneReviews®". PMID 20301298.
- ↑ Adam MP, Ardinger HH, Pagon RA, Wallace SE, Bean LJH, Stephens K; et al. (1993). "GeneReviews®". PMID 20301298.
- ↑ Adam MP, Ardinger HH, Pagon RA, Wallace SE, Bean LJH, Stephens K; et al. (1993). "GeneReviews®". PMID 20301298.
- ↑ Adam MP, Ardinger HH, Pagon RA, Wallace SE, Bean LJH, Stephens K; et al. (1993). "GeneReviews®". PMID 20301298.
- ↑ Adam MP, Ardinger HH, Pagon RA, Wallace SE, Bean LJH, Stephens K; et al. (1993). "GeneReviews®". PMID 20301298.
- ↑ Adam MP, Ardinger HH, Pagon RA, Wallace SE, Bean LJH, Stephens K; et al. (1993). "GeneReviews®". PMID 20301298.