Tuesday, September 8, 2020
Duchenne Muscular Dystrophy Awareness Day – 7 September 2020
Monday 7th September marks Duchenne Muscular Dystrophy (DMD) awareness day in both Australia and New Zealand, a global day to raise awareness of those affected by Duchenne and Becker Muscular Dystrophy (BMD).
DMD and BMD are both X-linked recessive disorders, caused by mutations in the dystrophin gene. This mutation can be caused by a certain part of the DNA being doubled or changed, or be missing altogether, meaning the gene will not work as it is supposed to. DMD and BMD can be passed down from a mother who is a carrier, or the gene can mutate spontaneously, and occurs in all ethnicities around the world.
The difference between Duchenne and Becker Muscular Dystrophy? The dystrophin gene encodes the protein dystrophin, which is essential to healthy muscle growth and functioning. Duchenne patients have a complete lack of the gene that produces dystrophin, while Becker patients have lower levels or a shorter version of the protein. People diagnosed with Becker Muscular Dystrophy have less severe symptoms that often show later in life.
Looking specifically at DMD, DMD affects between 1 in 3500 and 1 in 5000 live male births globally. Affected boys become symptomatic at 3-5 years of age due to proximal muscle weakness, presenting with difficulties with running, more frequent falls and difficulty rising from the floor. DMD is characterised by a well-known progression, including loss of mobility, reduced range of movement, development of deformities, and reduced independence with activity of daily living tasks.
At this stage there is no cure for DMD, however gene therapy offers potential for future treatment options. The gene for DMD was one of the first genes discovered, however therapy options are proving challenging due to the range of causes of the mutations that result in DMD. This range of causes means that one single gene therapy will not work for everyone diagnosed with DMD, however research is ongoing.
A treatment option that is now well established is the use of corticosteroids. Corticosteriod use is recommended by the current DMD care standards to start at around 4-6 years of age, and while the exact mechanism as to how they work is currently not well understood, evidence as to their benefit is being demonstrated. Koeks et al reviewed data collected through the TREAT-NMD global DMD database, identifying that corticosteroid use is common in boys until the age of 14. For those who had taken steroids, 79% were still ambulant at the age of 10, compared to 52% of those who had not. The median age when a boy was unable to ambulate in non-steriod treated group was 10 years old, compared to 13 years in the steroid group. Corticosteroids also significantly reduced the number requiring scoliosis surgery, the need for assisted ventilation and a lower incidence of cardio myopathy in those aged over 20 years of age.
Another important aspect of therapy is promotion of daily stretching, particularly of the lower limbs, and use of positioning and equipment to prevent development of contractures and deformities. The DMD Care standards reinforce that stretching needs to begin before loss of range of movement, and to initiate a standing programme using a standing device or wheelchair with upright positioning in the early non-ambulatory stage
This links to a current topic of conversation around the use of power standing wheelchairs for those diagnosed with DMD, with the chair being available for use as walking ability is lost. Research to support use of power standing chairs is currently limited, however evidence is emerging to support their use.
Bayley et all explored the effect of power standing chairs on range of movement and pain in adolescents with DMD over a 20 week period, and suggested that joint range of movement was preserved during the study period, including a potential increase in hip flexor length, despite a progressive loss of ambulation.
In a qualitative study by Vorster, Evan and Murphy et al, ‘Capacity to be able’ was the central theme that emerged from the data collected, with provision of a power stand up chair coming at a time when gross motor skills were declining. A number of benefits were observed with the use of power standing chairs, including participating in school activities that were usually done in standing, such as art or science, to independence with personal care tasks such as toileting and brushing teeth. More autonomy with participating in activities is considered important for adolescents and appeared to be associated with a strong emotional wellbeing. An important finding of the study was that individuals who received the power stand up chair after becoming non ambulatory appeared to gain less benefit, highlighting the need for timely provision of power stand up chairs for this group.
Access to power standing chairs for those diagnosed with DMD can be variable depending on the experience of the wheelchair and seating therapist and the funding systems available. While a power standing chair is not going to be suitable for all adolescents diagnosed with DMD, there is a group that have the potential to maintain a reasonable level of independence and well being if provided with one – at the right time. The use of corticosteroids now means that boys are now entering adolescence when they lose the ability to walk, and are at an age typically associated with increasing independence. Provision of a power standing chair will allow these adolescents to gain the therapeutic benefits associated with standing, in particular maintaining range of movement in their lower limbs, as well as maintaining independence in meaningful tasks at home and at school. While these benefits are in no way a cure for the underlying muscle weakness associated with DMD, it may allow this generation of boys and adolescents with DMD to make the most of the adult life that advances of technology are gradually giving them.
Save Our Sons Duchenne Foundation https://www.saveoursons.org.au/
Muscular Dystrophy New Zealand https://www.mda.org.nz/
Standards of Care for Duchenne Muscular Dystrophy https://vision-dmd.info/revised-standards-of-care-for-duchenne-muscular-dystrophy/
Koeks Z., Bladen C.L., Salgado D., Clinical Outcomes in Duchenne Muscular Dystrophy: a Study of 5345 Patients from the TREAT-NMD DMD Global Database (2017) Journal of Neuromuscular Diseases 4 293-306
Vorster N., Evans K., Murphy N., et al (2019) Power standing wheelchairs promote independence, health and community involvement in adolescents with Duchenne muscular dystrophy. Neuromuscular Disorders 29, 221-230
Bayley K., Parkinson S., Jacoby P etc al (2020) Benefits of power standing wheelchair devices for adolescents with Duchenne muscular dystrophy in the first year of use. Journal of Paediatrics and Child Health
Clinical Education Specialist
Rachel Maher graduated from the University of Otago in 2003 with a Bachelor of Physiotherapy, and later gained her Post Graduate Diploma in Physiotherapy (Neurorehabilitation) in 2010.
Rachel gained experience in inpatient rehabilitation and community Physiotherapy, before moving into a Child Development Service, working with children aged 0 to 16 years.
Rachel later moved into a Wheelchair and Seating Outreach Advisor role at Enable New Zealand in 2014, complementing her clinical knowledge with experience in NZ Ministry of Health funding processes.
Rachel joined Permobil in June 2020, and is passionate about education and working collaboratively to achieve the best result for our end users.