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25 Feb

Duchenne Muscular Dystrophy

One condition that can mean a person develops complex care needs is Duchenne Muscular Dystrophy (DMD).

What is Duchenne Muscular Dystrophy?

Muscular dystrophy is an umbrella term that encompasses a range of conditions, all of which have certain common features. Duchenne Muscular Dystrophy, or DMD is the most common form of muscular dystrophy. It mainly affects boys and men – around 1 in 4700 boys[i], and only about 1 in 50 million girls. It first appears in early childhood, and the average age at diagnosis of DMD is 4 years.

Symptoms of Duchenne

Duchenne is characterised by muscle weakness and wastage. As a genetic condition, the gene for Duchenne is always present, but the symptoms don’t fully appear until a child is around 2 years old.

Duchenne is one of the conditions that might be suspected if a boy doesn’t meet the usual physical milestones children reach by around age 2 or 3. There are some specific signs which children with Duchenne show – a particular gait, delay in walking and difficulty running or jumping, and using the ‘Gower Manoeuvre’[ii] to get up from the floor – this is where the large muscles in the hips and legs are weaker than usual so a child uses their arms to ‘walk’ themselves up from the floor.

As Duchenne progresses, more and more muscle groups are affected. There can be effects on the skeleton, with scoliosis (curvature of the spine) fairly common among boys with Duchenne. Duchenne eventually affects the muscles that control breathing, and more complex care input is needed. Duchenne can affect every muscle of the body, including the heart muscles.

Duchenne Muscular Dystrophy Stages

Duchenne can be described in four different stages, though progression through these stages isn’t always the same for everyone.

Stage 1: Early Ambulatory. Duchenne first becomes obvious as children begin to move more, when they learn to walk and run. Children with Duchenne don’t meet the same physical developmental milestones as children without, and struggle with jumping and running at this stage. Some muscles will be affected more than others, and the calf muscles may appear enlarged. The  Duchenne can also affect speech development.

Children with Duchenne may or may not show some degree of learning difficulties, ranging from mild to severe.

Stage 2: Late Ambulatory. Children at this stage can still walk and move independently, but it becomes more difficult, they seem physically weaker than other children their age and become fatigued very easily. Balance and gait are affected, and children with this stage of Duchenne often seem to walk balancing on their tiptoes.

Stage 3: Early Non-Ambulatory. At this stage of DMD, children lose the ability to walk, and need to use a wheelchair for getting around. They may be able to use their arms to propel the wheelchair, but those muscles will also weaken over time. The muscles which control breathing become weaker and people at this stage may need to begin to use or consider some extra respiratory support. This includes chest physio with respiratory physiotherapists, non-invasive ventilation, and devices designed to assist with coughing and clearing the chest and airways.

This is the stage where it may become clear that the heart muscles are affected – this is called cardiomyopathy, and should be monitored by a cardiology team. Cardiomyopathy is diagnosed with an ‘echo’ test – an echocardiogram is an ultrasound scan of the heart which shows whether there are structural and functional changes in the heart.

Stage 4: Late Non-Ambulatory. At the later stages of Duchenne, lots of support will be needed for respiratory function, and mechanical ventilation might be necessary some or all of the time. Swallowing difficulties are also more profound at this stage, and a nutritional support and a feeding tube might be required. People with late stages of Duchenne are usually still able to speak, though this might be somewhat restricted by their breathing difficulties, and there’s not usually any impact on understanding and cognitive abilities – people with even very complex physical needs due to Duchenne can still have an active role in society, relationships, social and work lives. At this stage, people with DMD usually need full support with all their care needs, and require help with continence needs, eating and drinking, and positioning in a bed or chair.

What Causes Duchenne Muscular Dystrophy?

Duchenne muscular dystrophy is caused by a genetic mutation[iii]. Genetic conditions are complicated; what we do know is that the gene for Duchenne is on the X chromosome. It is the gene that enables us to create the protein that protects our muscles from damage. As girls have two X chromosomes – one from each parent – a girl with the Duchenne gene will normally have one X chromosome with the mutation and one without, which means that girls are still able to produce the muscle-protecting protein and very rarely develop DMD.

Boys with the mutation on the X chromosome only have one X chromosome – from their mother – and a Y chromosome – from their father. If a boy has the genetic mutation for DMD on their X chromosome, they will develop DMD. Although full-blown DMD is rare in girls, around 8% of female carriers have some symptoms, and may particularly have cardiac problems[iv].

Dystrophin[v] is the protein our bodies produce to protect our muscles from damage – without enough dystrophin, even simple movements begin to cause the muscles to weaken.

The gene mutation which causes DMD sometimes happens spontaneously; it can happen even when there’s no one in the family with the same mutation. More commonly, it is passed down in families, and as it is on the X chromosome, a boy with DMD will have inherited it from his mother’s side. People with DMD in their family can access genetic counselling – information and tests to determine the likelihood of passing DMD on to their descendants, and what their options are.

Diagnosing Duchenne

To diagnose Duchenne, doctors ask about the signs and symptoms and family history of the child with suspected Duchenne. Blood tests are also taken which look for evidence of specific muscle damage. If the findings are in line with Duchenne or a similar condition, genetic testing – again by taking a blood sample – can confirm the diagnosis. Sometimes, doctors might take a muscle biopsy – this is a small sample of the muscle tissue – for examination. This is done under a local anaesthetic (numbing the area where the biopsy will be taken) and can help work out the amount of dystrophin in the muscle.

Some different muscle conditions can have similar symptoms to Duchenne so it’s important to have a proper diagnosis so that the right treatment can be given. With a diagnosis of Duchenne, the medical team and family can begin to plan the future management of the condition.

Treatments for Duchenne Muscular Dystrophy

Duchenne cannot be cured – there is currently no way to change a person’s genetic code if they have the genetic mutation for DMD. There is, however, ongoing research into treatment for Duchenne. Researchers are looking at ways to repair or replace genetic mutations[vi], and ways to enable the body to use different proteins genes to protect the muscles in the same way as dystrophin[vii].

There are lots of different forms of treatment and management of Duchenne muscular dystrophy[viii], and will involve strategies such as:

Physiotherapy: physiotherapists can help people with Duchenne learn the best ways to manage their movements and mobility. Good physiotherapy in muscular dystrophy can help people preserve their physical function and range of movement for as long as possible[ix]. Physiotherapists can also fit orthotic devices like braces to help support muscles and bones.

Occupational Therapy: Occupational therapists can help with adaptations to support home living, like grab rails, accessible bathroom equipment, and aids for independent living.

Gentle exercise: very gentle, low impact exercise like swimming can help people with DMD stay mobile as long as possible.

Medications: There are a few different medication options in DMD, and evidence for different treatments is improving all the time[x]. Corticosteroids in particular can help preserve muscle strength for a limited amount of time.

A healthy diet: Following a healthy diet[xi] is important for helping maintain the best possible general health.

healthy food concept

Some of the medications used for muscular dystrophy mean it’s extra important to focus on a nutritious diet; corticosteroids can make people gain weight and can also impair the absorption of calcium and affect bone structure. In later stages, swallowing can be a problem and careful management is needed to prevent malnutrition and dehydration[xii] – this might include fitting a feeding tube through the wall of the abdomen into the stomach (Percutaneous Endoscopic Gastrostomy or PEG).

Speech and language therapy (‘SALT’): speech and language therapists can help overcome the communication difficulties that can present with DMD especially as the muscles controlling breathing weaken and speech becomes difficult. Becoming dependent on mechanical ventilation can cause particular communication challenges, which speech therapists can help manage. A SALT (sometimes ‘SLT’) team are also the healthcare specialists who support people with swallowing difficulties, recommending management strategies like pureed diets and thickened fluids.

Cardiology input: DMD can affect heart function, causing reduced tone of the heart muscle and heart rhythm disturbances. Input from a cardiology team can help manage reduced heart function and arrhythmia risk. Permanent pacemakers are sometimes needed to manage heart rhythm problems.

Respiratory input: As the muscles which control breathing get weaker in the later stages of Duchenne, respiratory support[xiii] becomes more important, and more and more input is needed as time goes by.

Reduced ability to cough and clear the lungs makes a person more prone to chest infections and pneumonia, particularly when swallowing becomes compromised. Physiotherapists can help with coughing, and cough assist devices are available to help clear the lungs of fluid and mucous. As Duchenne progresses, alternatives to independent breathing may be necessary; non-invasive mechanical ventilation, often using a tracheostomy may become essential.

Home care: Some of the care needs a person with Duchenne will develop can most easily be managed by dedicated professional carers. Becoming less mobile makes a person more at risk of developing pressure damage, of having trouble with continence and constipation, and simply need more support to stay as active as possible and live the fullest life they can with the restrictions they’re developing.

Carers and nursing teams who specialise in complex care needs can also provide essential respiratory and nutritional support such as tracheostomy care, mechanical ventilation management, and PEG feeding. Families and informal carers can be as involved as they wish or can leave complex care to professionals and maintain a more traditional family role.

Living with Duchenne Muscular Dystrophy

Duchenne muscular dystrophy is a severely life-limiting condition. People with Duchenne usually only live into their 20s or 30s. Although life expectancy is shortened, there are ways to continue to have quality of life, and the right kind of support can enable people with Duchenne and their families to live the fullest possible life.

In the earlier stages, a family may be able to manage Duchenne at home independently with medical and nursing input for specific problems as they arise. As the child gets older, they move through the stages of Duchenne and are more affected by the muscle wastage. Their care needs will increase, and they will grow into adolescence and adulthood, making it more difficult to manage their physical needs without formal care input.

In the later stages of DMD, the affected person may begin to experience trouble breathing independently. At this point, they will need complex respiratory input like ventilators or devices which help them clear their lungs when the muscles that control coughing are affected.

Swallowing can also become a problem, making people with DMD at risk of aspiration pneumonia (a condition where food or drink enters the lungs), and there are some options for staying well fed and hydrated without the ability to swallow safely. Staying at home at that stage means having support with all their personal care needs and more complex support for nutrition and respiratory needs.

Resources

Living with Duchenne Muscular Dystrophy means making some major adjustments, and Duchenne affects more than just the individual with the condition.  If you or a family member has Duchenne, there are organisations and groups which can offer life-changing support.

UK based groups supporting people with Duchenne and other sorts of muscular dystrophy:

https://www.duchenneuk.org/

https://www.myotonicdystrophysupportgroup.org/

https://www.actionduchenne.org/

https://www.musculardystrophyuk.org/

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[i] Dooley, J., Gordon, K. E., Dodds, L., & MacSween, J. (2010). Duchenne Muscular Dystrophy: A 30-Year Population-Based Incidence Study. Clinical Pediatrics49(2), 177–179. https://doi.org/10.1177/0009922809347777

[ii] Shrestha S, Munakomi S. Gower Sign. (2020). StatPearls Publishing https://www.ncbi.nlm.nih.gov/books/NBK540973/

[iii] Emery, A. E., Muntoni, F., & Quinlivan, R. C. (2015). Duchenne muscular dystrophy. OUP Oxford. https://doi.org/10.1016/j.ejpn.2004.05.004

[iv] Song, T. J., Lee, K. A., Kang, S. W., Cho, H., & Choi, Y. C. (2011). Three cases of manifesting female carriers in patients with Duchenne muscular dystrophy. Yonsei medical journal52(1), 192. http://doi.org/10.3349/ymj.2011.52.1.192

[v]Hoffman, E. P., Brown Jr, R. H., & Kunkel, L. M. (1987). Dystrophin: the protein product of the Duchenne muscular dystrophy locus. Cell, 51(6), 919-928.  https://doi.org/10.1016/0092-8674(87)90579-4

[vi] Guiraud, S., Chen, H., Burns, D. T., & Davies, K. E. (2015). Advances in genetic therapeutic strategies for Duchenne muscular dystrophy. Experimental physiology100(12), 1458-1467. https://doi.org/10.1113/EP085308

[vii] Gillis, J. M. (2004). Utrophin, a way to cure Duchenne muscle dystrophy. Medecine Sciences:. https://doi.org/10.1051/medsci/2004204442

[viii]Bushby, K., Finkel, R., Birnkrant, D. J., Case, L. E., Clemens, P. R., Cripe, L., … & DMD Care Considerations Working Group. (2010). Diagnosis and management of Duchenne muscular dystrophy, part 1: diagnosis, and pharmacological and psychosocial management. The Lancet Neurology, 9(1), 77-93. https://doi.org/10.1016/S1474-4422(09)70271-6

[ix] Gianola, S., Pecoraro, V., Lambiase, S., Gatti, R., Banfi, G., & Moja, L. (2013). Efficacy of muscle exercise in patients with muscular dystrophy: a systematic review showing a missed opportunity to improve outcomes. PloS one8(6), e65414. https://doi.org/10.1371/journal.pone.0065414

[x] Strober, J.B. Therapeutics in Duchenne muscular dystrophy. NeuroRX 3, 225–234 (2006). https://doi.org/10.1016/j.nurx.2006.01.005

[xi]Davidson, Z. E., & Truby, H. (2009). A review of nutrition in Duchenne muscular dystrophy. Journal of human nutrition and dietetics, 22(5), 383-393. https://doi.org/10.1111/j.1365-277x.2009.00979.x

[xii]Michel Toussaint, Zoe Davidson, Veronique Bouvoie, Nathalie Evenepoel, Jurn Haan & Philippe Soudon (2016) Dysphagia in Duchenne muscular dystrophy: practical recommendations to guide management, Disability and Rehabilitation, 38:20, 2052-2062 https://doi.org/10.3109/09638288.2015.1111434

[xiii] Sheehan, D. W., Birnkrant, D. J., Benditt, J. O., Eagle, M., Finder, J. D., Kissel, J., … & Wolfe, L. F. (2018). Respiratory management of the patient with Duchenne muscular dystrophy. Pediatrics142(Supplement 2), S62-S71.  https://doi.org/10.1542/peds.2018-0333H