Muscular Dystrophy

Original Editor - Lucinda hampton

Top Contributors - Rucha Gadgil and Kim Jackson  

Introduction[edit | edit source]

Muscular Dys.jpg

The term "muscular dystrophy" incorporates an assortment of hereditary disorders that lead to progressive, generalized disease of the muscle prompted by inadequate or missing glycoproteins in the muscle cell plasma membrane. Muscular dystrophy (MD) is a non-communicable disorder with abundant variations. Each has its pattern of inheritance, onset period, and the rate at which muscle is lost. Alterations in specific genes cause different representations of this disease[1].

Muscular dystrophies are characterized by progressive muscular atrophy and weakness. In most varieties the muscles of the limb girdles (the pelvic and shoulder muscles) are involved[2]. Over time, people with MD lose the ability to do things like walk, sit upright, breathe easily, and move their arms and hands[3].

There is no cure for MD. Physiotherapists and other health professionals work on improving muscle and joint function and slowing muscle deterioration so people with MD can live as actively and independently as possible.

Image: A social worker from Tamil Nadu, India, was suffering from muscular dystrophy. She (along with her sister) made helping people with similar ailment their life's aim by building a center to help with the treatment of physically challenged people. She passed away on 15th January, 2017.

For pages on individual MDs see Muscular Dystrophy

Eitiology[edit | edit source]

MuscularDystrophy.png

Muscular dystrophy most often results from defective or absent glycoproteins in the muscle membrane. Each type of muscular dystrophy results from different gene deletions or mutations, causing various enzymatic or metabolic defects. Image: In the affected muscle (right), the tissue has become disorganized and the concentration of dystrophin (green) is greatly reduced.  Dystrophin forms an integral part of a muscle's cytoskeleton and links the contractile apparatus to the sarcolemma.

  • In 1986, researchers discovered the gene that, when defective or flawed, causes Duchenne muscular dystrophy. The muscle protein associated with this gene was named dystrophin.[4] The dystrophin gene is the largest in the human genome, with 79 exons. The dystrophin gene is subject to a high rate of spontaneous mutations because of its enormous size (>2 × 106 bases)[1].
  • Duchenne muscular dystrophy(DMD) occurs when that gene fails to make dystrophin. Becker muscular dystrophy occurs when a different mutation in the same gene results in some dystrophin, but it's either not enough or it's poor in quality. Scientists have discovered and continue to search for the genetic defects that cause other forms of muscular dystrophy.
  • Most muscular dystrophies are a form of an inherited disease called X-linked disorders or genetic diseases that mothers can transmit to their sons even though the mothers themselves are unaffected by the disease[5].

Epidemiology[6][7][edit | edit source]

Most Common:

  1. Childhood Muscular Dystrophy - Duchenne: The pooled global DMD prevalence was 7.1 cases per 100,000 males and 2.8 per 100,000 in the general population, while the pooled global DMD birth prevalence was 19.8 per 100,000 live male births.[7]
  2. Adult Muscular Dystrophy - Myotonic: The prevalence estimates per 100,000 were 8.26 for myotonic dystrophy,
  3. 3.95 for Facioscapulo Humeral Dystrophy,
  4. 1.63 for limb-girdle muscular dystrophy,
  5. 0.99 for congenital muscular dystrophies.
  • Prevalence Of Muscular Dystrophy (General Population): 16 to 25.1 per 100,000.
  • Frequency Of Muscular Dystrophy (General Population): 1 per 3,000 to 8,000.
  • Incidence Of Muscular Dystrophy (Male Births): 1 per 5,000 or 200 per 1,000,000

Management[edit | edit source]

Wheelchair child.jpg

There is no cure for muscular dystrophy, but treatments can help manage symptoms and improve quality of life.

1.Medical Interventions

  • Anti-arrhythmics
  • Anti-epileptics
  • Anti-myotonic drugs
  • Non-steroidal anti-inflammatory drugs (NSAIDs)
  • Steroids

2. Surgical Interventions

  • Defibrillator or a cardiac pacemaker
  • Contracture release
  • Shoulder surgery
  • Spinal correction

3. Other Interventions

  • Supportive physiotherapy
  • Supportive bracing
  • Supportive counseling
  • Genetic counseling[1]

Physiotherapy[edit | edit source]

Pool.jpg

The goal of physical therapy is to improve strength in the large muscle groups and prevent scoliosis and contractures.

Physical therapy for muscular dystrophy may involve:

  • Range of motion exercises
  • Stretching
  • Low-impact workouts, such as swimming or water exercise (aquatic therapy)[5]
  • Supportive Bracing: This helps to maintain normal function as long as possible  Proper wheelchair seating is essential. Molded ankle-foot orthoses help stabilize gait in patients with foot drop. Lightweight plastic ankle-foot orthoses (AFOs) for footdrop are extremely helpful. Footdrop is easily treatable with AFOs. Individuals with scapulohumeral muscular dystrophy remain ambulatory for 40 or more years.  Occasionally, walking may become hampered by paraspinal muscle contractures; in that case, a wheelchair may assist the individual when it is necessary to cover long distances. Bracing may be performed for function eg dorsiflexion of the feet with ankle-foot orthotics to prevent tripping or to provide support and comfort[1].

Children at school may need physio interventions such as providing:

  • Adaptive or assistive technological devices in the classroom (such as a keyboard for writing)
  • Use a wheelchair or wear joint braces
  • Use a ventilator for breathing
  • Need special considerations about latenesses, absences, shortened school days, and missed classwork and homework due to physical therapy sessions[3]

Complications[edit | edit source]

Muscular dystrophy gait.jpg

The complications of muscular dystrophy depend on the type. Some types are mild, while others are serious and get worse very fast. Worsening muscle weakness can affect the ability to walk, breathe, swallow, and speak. Complications can include:

  1. Breathing problems. Progressive weakness in the breathing muscles makes it hard to take a breath (raising the risk for eg lung infections such as pneumonia).
  2. Scoliosis.
  3. Heart problems. Some types of muscular dystrophy cause abnormal and dangerous changes in the heartbeat (a pacemaker may be needed). Muscular dystrophy can also cause cardiomyopathy leading to heart failure. Most patients die before the age of 30 years due to cardiopulmonary failure.[1]
  4. Swallowing difficulty. The weakness affects the muscles in the esophagus and causes problems with chewing and swallowing. This can lead to choking. Some people with muscular dystrophy will need a feeding tube.
  5. Contractures. Bracing and tendon release surgery can help prevent some contractures.
  6. Vision problems. Some types of muscular dystrophy cause cataracts.[8][9]
  7. Need for a wheelchair. Some people with muscular dystrophy eventually need to use a wheelchair.

References[edit | edit source]

  1. 1.0 1.1 1.2 1.3 1.4 LaPelusa A, Kentris M. Muscular Dystrophy. StatPearls [Internet]. 2020 Jul 21.Available from: https://www.ncbi.nlm.nih.gov/books/NBK560582/(accessed 24.2.2021)
  2. Britannica Muscular Dystrophy Available from: https://www.britannica.com/science/muscle-disease/The-muscular-dystrophies(accessed 24.2.2021)
  3. 3.0 3.1 Kidz health MD fact sheet Available from: https://kidshealth.org/en/parents/md-factsheet.html (last accessed 24.2.2021)
  4. Allen DG, Whitehead NP, Froehner FC. Absence of Dystrophin Disrupts Skeletal Muscle Signaling: Roles of Ca2+, Reactive Oxygen Species, and Nitric Oxide in the Development of Muscular Dystrophy. Physiol Rev. 2016; 96(1): 253–305. Doi: 10.1152/physrev.00007.2015
  5. 5.0 5.1 WebMD MD Available from: https://www.webmd.com/children/understanding-muscular-dystrophy-basics?page=-1281(accessed 24.2.2021)
  6. Mah JK, Korngut L, Fiest KM, Dykeman J, Day LJ, Pringsheim T et al. A Systematic Review and Meta-analysis on the Epidemiology of the Muscular Dystrophies. Can J Neurol Sci. 2016; 43(1):163-77. Doi: 10.1017/cjn.2015.311.
  7. 7.0 7.1 Crisafulli S, Sultana J, Fontana A, Salvo F, Messina S, Trifirò G. Global epidemiology of Duchenne muscular dystrophy: an updated systematic review and meta-analysis. Orphaned J Rare Dis. 2020; 15:141. Doi.org/10.1186/s13023-020-01430-8
  8. Kidd A, Turnpenny P, Kelly K, Clark C, Church W, Hutchinson C et al. Ascertainment of myotonic dystrophy through cataract by selective screening. J Med Genet. 1995; 32:519–23.
  9. Kang MJ, Yim HB, Hwang HB. Two cases of myotonic dystrophy manifesting various ophthalmic findings with genetic evaluation. Indian J Ophthalmol. 2016; 64(7):535-7. Doi: 10.4103/0301-4738.190157.