This document summarizes Duchenne muscular dystrophy (DMD), a genetic disorder characterized by progressive muscle degeneration and weakness. It discusses the disease pathogenesis, symptoms in four stages, incidence, diagnosis, management, and multidisciplinary care. Management includes corticosteroids to prolong ambulation, physical therapy, bracing, spinal surgery, cardiac and respiratory care including ventilation, nutrition support, and psychosocial interventions. DMD significantly reduces life expectancy but improvements in clinical care have increased average survival into the late 20s or beyond.

1. By Grainne O’Keeffe

2.  Intro
 Aetiology
 Pathogenisis
 Incidence
 Diagnosis
 Family support
 Client’s case
 MDT Management

3.  An X linked neuromuscular disease characterised by rapidly progressing
muscle weakness and wasting, (WHO, 2013).
Four phases
 Early phase (<6 yrs): clumsy, fall frequently, difficulty jumping or
running, enlarged muscles, contractures.
 Transitional Phase (ages 6-9): Trunk weakness (Gowers
manouvre), muscle weakness, heart problems, fatigue.
 Loss of ambulation (ages 10-14): by 12 yrs most boys use a powered
wheelchair. Scoliosis due to constant sitting and back weakness, UL
weakness make ADL’s difficult (retain use of fingers).
 Late stage (15+): life threatening heart and respiratory problems more
prevalent, dyspnea, oedema of the LL’s. Average age of death is 19 yrs in
untreated DMD but due to improvements in clinical care in many centres
the average age of death is the late twenties or beyond, (Bushby et
al, 2005).

4.  Sex linked: X-linked genetic recessive disorder
 Inherited by the carrier mother/sporadic mutation in the
mothers egg cell (1/3 of cases).
 Results in an abnormality in the genetic code for the
protein dystrophin resulting in lack of dystrophin.
(Nowak and Davies, 2004)

5.  The dystrophin gene is the largest in the human genome and is
prone to mutation.
 60% of dystrophin mutations are large insertions or deletions that
lead to frame shift errors downstream, whereas approximately
40% are point mutations/duplications or small frame shifts/
rearrangements (Hoffman, 2001).

6.  Dystrophin links the muscle cells to
the extracellular matrix stabilising
the membrane and protecting the
sarcolemma from the stresses that
develop during muscle contraction.
 Mechanically induced damage through
eccentric contractions puts a high
stress on fragile membranes and
provokes micro-lesions that could
eventually lead to loss of calcium
homeostasis, and cell death.
 Imbalance between necrotic and
regenerative processes: early phase
of disease.
 Later phases the regenerative
capacity of muscle fibers are
exhausted and fibers are gradually
replaced by connective tissue and
adipose tissue.
(Deconinck and Dan, 2007)

7.  Incidence: 1 in 3600-6000 (Emery, 1991), (Bushby et al, 2010), Bradley &
Parsons, 1998)
 Between 1 February 1993 to 30 June 1994 – DMD incidence was 1 in
12,200 in Northern Ireland (Hughes et al, 1996).
 1 in 4200 – The Netherlands (Essen et al, 1992).
 1 in 5,600 to 1 in 7,700 DBMD males through 5-24 years in four states in
the U.S.A. 1982-2002. (Ciafoloni et al, 2009)
 First symptoms noticed on average at 3.6 years (MDSTARnet, 2007)

8.  Mean age of diagnosis in cases without family hx is >4 ½ years (bushby et al, 2005).
 Delay in diagnosis of 2 ½ yrs (Bushby et al, 2005), (Parsons et al, 2004)
(Bushby et al, 2010)

9.  Family support is NB at this time: provide contact with a named
member of staff and provide details of parental support groups .
 http://www.parentprojectmd.org
 www.dfsg.org.uk
 http://www.mdi.ie/index.html
 http://www.informingfamilies.ie/

10.  Age: 5 ½ years.
 PC: rare Xp21 mutation with Point mutation of exon 7 of the
dystrophin gene resulting in complete absence of dystrophin.
 Presentation: (Early ambulatory stage ) - Ambulant, weight – 50th
%, hypertrophy of the calves, +ve Gower's sign, mild lordosis.
 Problem List: Poor attention, Speech delay (uses pecs),
?hyperactivity(reported by mother), proximal weakness of lower
and upper limbs and neck flexors, epistaxis, poor balance, gait-
waddle/flat footed, muscle spasm of calves.
 PMHX: Initially presented with developmental delays before he
was diagnosed.

11.  Corticosteroids: prednisolone 20 mg daily.
 Splinting for prevention of contractures at night time.
 Check ups with neurologist every 6 months.
 Physiotherapy
LTG’s
 Improve upper limb strength
 Improve lower limb strength
 Improve balance
 Improve participation in play
STG’s
 Increase throwing distance of bean bag from 1 meter to 1 ¼ meters in 3 weeks.
 Increase kicking distance of soccer ball while on gym matt from 1 meter to 1 ½ meter in 3 weeks.
 Improve one legged stance to 2 seconds in 3 weeks.
Other
Family Support and services
SLT
Psychology
OT

12. (Bushby et al, 2010)

13. (Bushby et al, 2010)

14.  Management of muscle extensibility and joint contractures:
stretching and positioning, assistive devices for MSK MGT
(orthoses, standing devices), surgical mgt for LL contractures
(Triple arthrodesis).
 Improvement, maintenance and support of muscle strength and
function: Recommendations for physical activity - regular
submaximum (gentle) functional strengthening/activity,
including a combination of swimming-pool exercises and
recreation-based exercises in the community.
 Steroid prescription and management
(Fowler et al 2002), (Fowler, 1982), (Bushby et al 2010)

15.  Currently best treatment available
 Improve Muscle Strength and function
 Significantly slow the progression of muscle weakness
 Prolong ambulation
 Delsy the onset of respiratory and/or cardiac dysfunction
 Use with caution as side effects include weight
gain, reduced bone density, hyperactivity, failure to gain
height.
 Pednisone/prednisolone – 0.75 mg/kg/day
 Deflazacort – 0.9 mg/kg/day

16.  90 % of boys with DMD are likely to develop a clinically significant
scoliosis.
 Surgery has shown to be effective in correcting scoliosis and
Success rates are likely to be highest and complication rates
lowest if surgery is performed when the spine is still mobile at a
Cobb angle of 20–40% (Cervellati et al, 2004) .
 Spinal bracing for those unable for surgery.
 Triple arthrodesis may be required
 Bone health: Fractures (long bone and
vertebral)Osteopenia, Osteoporosis Kyphoscoliosis, Bone
pain, Reduced QOL – DEXA scans, serum/urine tests, spine
readiograph – Vit D, Calcium, Biphosphonates.

17. (Eagle et al, 2007) Kaplan–Meier survival plot to show the impact of spinal surgery and
ventilation on survival. Survival curves are significantly different p = 0.0001.

18.  Death is due to cardiac dysfunction in 10% of cases (Gulatie et
al, 2005).
 Dilated cardiomyopathy: A condition in which the heart becomes
weakened and enlarged. As a result, the heart cannot pump
enough blood to the rest of the body.
 Death due to cardiomyopathy is expected to rise now that life
expectancy increases, (Bushby et al, 2003).
 It is estimated that 20–30% of DMD boys have left ventricular
impairment on echocardiography by age 10 years (Bushby et al,
2005).
 Cardiac mgt should be implemented at diagnosis as clinical
symptoms appear later than initial cardiac dysfunction,
echocardiogram & electrocardioram – at 6 yrs, every 2 yrs up to
age 10 and annually after 10 yrs +.
 ACE and beta blockers
(American academy of Paediatrics, 2005)

19. Respiratory MGT

20. Panel 1: Respiratory interventions indicated in patients with Step 3: nocturnal ventilation
Duchenne Nocturnal ventilation† is indicated in patients who have
muscular dystrophy any of the following:
Step 1: volume recruitment/deep lung infl ation technique • Signs or symptoms of hypoventilation (patients with FVC
Volume recruitment/deep lung infl ation technique (by self-infl ating <30% predicted are at
manual ventilation bag especially high risk)
or mechanical insuffl ation–exsuffl ation) when FVC <40% predicted • A baseline SpO2
Step 2: manual and mechanically assisted cough tech <95% and/or blood or end-tidal CO2
• Respiratory infection present and baseline peak cough fl ow <270 >45 mm Hg while awake
L/min* • An apnoea–hypopnoea index >10 per hour on
• Baseline peak cough fl ow <160 L/min or maximum expiratory polysomnography or four or more
pressure <40 cm water episodes of SpO2
• Baseline FVC <40% predicted or <1·25 L in older teenager/adult <92% or drops in SpO2
of at least 4% per hour of sleep
Optimally, use of lung volume recruitment and assisted
cough techniques should always
precede initiation of non-invasive ventilation
Step 4: daytime ventilation Step 5: tracheostomy
In patients already using nocturnally assisted ventilation, daytime Indications for tracheostomy include:
ventilation‡ is • Patient and clinician preference§
indicated for: • Patient cannot successfully use non-invasive ventilation
• Self extension of nocturnal ventilation into waking hours • Inability of the local medical infrastructure to support
• Abnormal deglutition due to dyspnoea, which is relieved by non-invasive ventilation
ventilatory assistance • Three failures to achieve extubation during critical illness
• Inability to speak a full sentence without breathlessness, and/or despite optimum use of
• Symptoms of hypoventilation with baseline SpO2 non-invasive ventilation and mechanically assisted cough
<95% and/or blood or end-tidal CO2 • The failure of non-invasive methods of cough assistance
>45 mm Hg while awake to prevent aspiration of
Continuous non-invasive assisted ventilation (with mechanically secretions into the lung and drops in oxygen saturation
assisted cough) can below 95% or the patient’s
facilitate endotracheal extubation for patients who were intubated baseline, necessitating frequent direct tracheal suctioning
during acute via tracheostomy
illness or during anaesthesia, followed by weaning to nocturnal non-
invasive assisted
ventilation, if applicable

21. Psychosocial AX
 Emotional adjustment/coping
 Neurocognitive
 Autism spectrum disorders
 Social work
Psychosocial Interventions
 Psychotherapy
 Pharmacological interventions
 Educational interventions
 Social interaction interventions
 Care/support interventions

22.  Nutritionist/dietician: to guide the patient to maintain good
nutritional status to prevent both under nutrition/malnutrition
and being overweight/obese, and to provide a well-
balanced, nutrient-complete diet.
 SLT: To monitor and treat swallowing problems, to prevent
aspiration and weight loss, and to assess and treat delayed
speech and language problems.
 Clinical Nurse specialist: Family Support and Services
 OT: Continue previous measures Provision of appropriate
wheelchair and seating, and aids and adaptations to allow
maximum independence in ADL, function, and participation.

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27. (Parsons et al, 2004) Milestone Late/never Median age
achieved (range
(%) case achieved)
numbers (months)
Walking alone (89%) 16/18 16 (13–27)
Sitting alone (67%) 12/18 8 (5–16)
Meaningful (53%) 9/17 29 (20–43)
sentences
Single words (47%) 8/17 13 (9–24)