The document discusses muscular dystrophy, focusing on Duchenne muscular dystrophy (DMD), which is a genetically determined muscular disease characterized by progressive muscle degeneration and weakness, primarily impacting males. DMD is associated with the deficiency of dystrophin, leading to a variety of symptoms including muscle weakness, contractures, and decreased pulmonary function. The document also outlines diagnostic approaches, clinical presentations, functional assessments, and the role of physical therapy interventions to manage the disease.

1. Muscular Dystrophy
Dr. Asir John Samuel, MPT, PhD (Physiotherapy)
Associate Professor,
Maharishi Markandeshwar Institute of Physiotherapy and Rehabilitation
(MMIPR),
Maharishi Markandeshwar (Deemed-to-be University),
Mullana-Ambala, Haryana, India

2. Muscular dystrophy
• Muscular dystrophy describes a group of
muscle diseases that are genetically
determined and have a steadily progressive
degenerative course
Dr. Asir John Samuel, MPT, PhD, Assoc. Prof. 2

3. Duchenne muscular dystrophy (DMD)
• Duchenne muscular dystrophy (DMD) in 1987
• Relationship between the different
dystrophies and dystrophin–glycoprotein
complex (DGC)
Dr. Asir John Samuel, MPT, PhD, Assoc. Prof. 3

4. Dystrophin–glycoprotein complex
(DGC)
• Dystrophin–glycoprotein complex (DGC) is a
group of proteins that links the
subsarcolemmal cytoskeleton and
extracellular matrix with the contractile
apparatus of the muscle and gives stability to
the muscle cell membrane
Dr. Asir John Samuel, MPT, PhD, Assoc. Prof. 4

5. Muscle cell membrane and associated protein
complexes implicated in muscle disease
Dr. Asir John Samuel, MPT, PhD, Assoc. Prof. 5

6. Muscular dystrophy - Types
• When dystrophin is deficient, the result is
Duchenne or Becker muscular dystrophy
(BMD)
• When one of the sarcoglycan proteins is
deficient, other limb-girdle muscular
dystrophies (LGMDs) result
• A deficiency of Merosin results in one specific
type of congenital muscular dystrophy (CMD)Dr. Asir John Samuel, MPT, PhD, Assoc. Prof. 6

7. Muscular dystrophy - Types
• DMD and BMD are also known as
dystrophinopathies because dystrophin is deficient
in these conditions
• LGMDs are also known as sarcoglycanopathies
because one of the sarcoglycan proteins is deficient
in these conditions
• Merosin negative congenital muscular dystrophy is
the result of a deficiency of MerosinDr. Asir John Samuel, MPT, PhD, Assoc. Prof. 7

8. Spinal muscular atrophy (SMA)
• Spinal muscular atrophy (SMA) refers to
neurogenic disorders whose underlying
pathology affects sensory neurons and spinal
interneurons
• As a result, affects the anterior horn cell
Dr. Asir John Samuel, MPT, PhD, Assoc. Prof. 8

9. Duchenne muscular dystrophy
• DMD, also known as pseudohypertrophic
muscular dystrophy or progressive muscular
dystrophy
• Most prevalent and severely disabling of the
childhood neuromusclular disorders
• Approximately 1 in 3500 live male births
Dr. Asir John Samuel, MPT, PhD, Assoc. Prof. 9

10. Duchenne muscular dystrophy
• Dystrophinopathy in which the child becomes
weaker and usually dies of respiratory
insufficiency and/or heart failure due to
myocardial involvement in the second or third
decade of life
Dr. Asir John Samuel, MPT, PhD, Assoc. Prof. 10

11. Duchenne muscular dystrophy
• X-linked inheritance pattern to DMD whereby
male offspring
• Inherit the disease from their mothers, who
are most often asymptomatic
• Defect to be a mutation at Xp21 in the gene
coding for the protein dystrophin
Dr. Asir John Samuel, MPT, PhD, Assoc. Prof. 11

12. DMD - Diagnosis
• Clinical presentation gives the first clues to the
diagnosis
• Laboratory findings include an abnormally
high serum creatine kinase (CK) level, which is
50 to 200 times the normal level and usually
ranges from 15,000 to 35,000 IU/L (normal
less than 160 IU/L)Dr. Asir John Samuel, MPT, PhD, Assoc. Prof. 12

13. DMD - Diagnosis
• Muscle biopsy may be performed to confirm
the diagnosis and shows degenerating and
regenerating fibers, inflammatory infiltrates,
and increased connective tissue and adipose
cells
• Immunohistologic staining of the tissue
reveals the absence of dystrophin along the
muscle cell membranes
Dr. Asir John Samuel, MPT, PhD, Assoc. Prof. 13

14. After diagnosis - DMD
• With the availability of genetic analysis, all
male family members may be screened for the
disorder
• All female family members may be screened
for their carrier status once a mutation is
identified
Dr. Asir John Samuel, MPT, PhD, Assoc. Prof. 14

15. DMD - Pathophysiology
• Absence of dystrophin leads to a reduction in
all of the dystrophin-associated proteins in the
muscle cell membrane and
• Causes a disruption in the linkage between
the subsarcolemmal cytoskeleton and the
extracellular matrix
Dr. Asir John Samuel, MPT, PhD, Assoc. Prof. 15

16. DMD - Pathophysiology
• Lack of dystrophin is thought to cause
sarcolemmal instability and
• An increase susceptibility to membrane
microtears, which may be exacerbated by
muscle contractions.
Dr. Asir John Samuel, MPT, PhD, Assoc. Prof. 16

17. DMD - Pathophysiology
• Increased calcium channel leaks, and an
increase in reactive oxygen species
• Increase in reactive oxygen species is activated
through a pathway driven by
mechanotransduction by the microtubule
cytoskeleton of the cell
Dr. Asir John Samuel, MPT, PhD, Assoc. Prof. 17

18. DMD - Pathophysiology
• Activation of this signaling pathway results
from membrane stress and
• Ultimately impacts calcium signaling and
results in an increase in calcium which raises
intracellular calcium levels, leading to muscle
cell necrosis
Dr. Asir John Samuel, MPT, PhD, Assoc. Prof. 18

19. Clinical Presentation
• Onset of the disorder is insidious
• Symptoms appear between 2 and 5 yrs of age
• If not noticed for months or years, then
• May be misdiagnosed for years
Dr. Asir John Samuel, MPT, PhD, Assoc. Prof. 19

20. Clinical Presentation
• Reluctance to walk or run at appropriate ages,
• Falling, and difficulty getting up off the floor,
• Toe-walking,
• Clumsiness, and
• An increase in the size of the gastrocnemius
muscles
Dr. Asir John Samuel, MPT, PhD, Assoc. Prof. 20

21. Pseudohypertrophy
• Increase in the size of
the gastrocnemius
muscles
• “Pseudohypertrophy,” is
marked by a firm
consistency of the
muscle when palpated
Dr. Asir John Samuel, MPT, PhD, Assoc. Prof. 21

22. Clinical Presentation and Progression
• The weakness is steadily progressive with
proximal muscles tending to be weaker earlier
and to progress faster
• Weakness of the hip and knee extensors
• often results in an exaggerated lumbar
lordosis
Dr. Asir John Samuel, MPT, PhD, Assoc. Prof. 22

23. Clinical Presentation and Progression
• Child attempts to broaden the base of support
during walking and
• Thus develops a gait that resembles waddling
• Child may develop iliotibial band (ITB)
contractures, which are made worse by this
wide-based stance
Dr. Asir John Samuel, MPT, PhD, Assoc. Prof. 23

24. Gowers sign• As the weakness
progresses, the child
rises from the floor
by “climbing up the
legs.”
• This maneuver,
known as Gowers
sign, is indicative of
proximal muscle
Dr. Asir John Samuel, MPT, PhD, Assoc. Prof. 24

25. Contractures
• Plantarflexion at the ankle,
• Inversion of the foot
• Flexion at both the hips and knees
Dr. Asir John Samuel, MPT, PhD, Assoc. Prof. 25

26. ROM
• Loss of range of motion (ROM),
• Hamstrings,
• Hip flexors,
• ITBs, and
• Heel cords
Dr. Asir John Samuel, MPT, PhD, Assoc. Prof. 26

27. Contracture
• An increasing degree of contracture is seen at
the hips and knees,
• Upper extremity contractures begin to
develop in the elbows, shoulders and long
finger flexors
• More time sitting
Dr. Asir John Samuel, MPT, PhD, Assoc. Prof. 27

28. Slow in Functional activities
• Functional activities may be performed more
slowly by children with DMD than by typically
developing children
• Those affected are able to walk, climb stairs
and stand up from the floor without too much
difficulty until 6 or 7 years of age
Dr. Asir John Samuel, MPT, PhD, Assoc. Prof. 28

29. DMD and BMD
• Loss of unassisted ambulation at 9 to 10 years
of age
• Loss of ambulation should be by the age of 13
after which the patient would be considered
to have either BMD or an intermediate
phenotype
Dr. Asir John Samuel, MPT, PhD, Assoc. Prof. 29

30. Prognosis
• Child choose to use long-leg braces and
continue to walk as an exercise ambulator for
an additional year
• But will need help getting to and from
standing
• Partial weightbearing walker may also be used
at this stage
Dr. Asir John Samuel, MPT, PhD, Assoc. Prof. 30

31. Dr. Asir John Samuel, MPT, PhD, Assoc. Prof. 31

32. Dr. Asir John Samuel, MPT, PhD, Assoc. Prof. 32

33. Functional Grades: Arms and
Shoulders – Brooke (1983)
1 - Standing with arms at the sides, the patient
can abduct the arms in a full circle until they
touch above the head.
2 - The patient can raise the arms above the
head only by flexing the elbow (i.e., by
shortening the circumference of the movement)
or by using accessory muscles.Dr. Asir John Samuel, MPT, PhD, Assoc. Prof. 33

34. Functional Grades: Arms and
Shoulders – Brooke (1983)
3 - The patient cannot raise hands above the
head, but can raise an 8-oz glass of water to the
mouth (using both hands if necessary).
4 - The patient can raise hands to the mouth,
but cannot raise an 8-oz glass of water to the
mouth.
Dr. Asir John Samuel, MPT, PhD, Assoc. Prof. 34

35. Functional Grades: Arms and
Shoulders – Brooke (1983)
5 - The patient cannot raise hands to the mouth,
but can use the hands to hold a pen or to pick
up pennies from a table.
6 - The patient cannot raise hands to the mouth
and has no useful function of the hands.
Dr. Asir John Samuel, MPT, PhD, Assoc. Prof. 35

36. Problem list
1. Weaknes
2. Decreased active and passive ROM
3. Ambulation dysfunction
4. Decreased functional ability
5. Decreased pulmonary function
6. Emotional trauma—individual and family
7. Progressive scoliosis
8. Pain Dr. Asir John Samuel, MPT, PhD, Assoc. Prof. 36

37. Physical Therapy Intervention
1. Prevent deformity
2. Prolong functional capacity
3. Improve pulmonary function
4. Facilitate the development and assistance of
family support and support of others
5. Control pain, if necessary
Dr. Asir John Samuel, MPT, PhD, Assoc. Prof. 37

38. Preventing Deformity
• Tendency for development of plantarflexion
contractures
• Daily stretching of the Achilles tendons should
slow down the development of this deformity
• Night splints
• 10 and 15 reps, holding at least 15 seconds,
performed at least once, and preferably twice,
daily
• Serial casting
Dr. Asir John Samuel, MPT, PhD, Assoc. Prof. 38

39. Activity Level/Active Exercise
• Care should be taken to avoid overusing muscles
and causing fatigue
• Signs of overuse weakness include feeling weaker
30 minutes postexercise or excessive soreness 24
to 48 hours after exercise
• Other signs include severe muscle cramping,
heaviness in the extremities, and prolonged
shortness of breathDr. Asir John Samuel, MPT, PhD, Assoc. Prof. 39

40. Activity Level/Active Exercise
• Eccentric muscle activities such as walking or
running downhill and closed chain exercises
such as squats should be avoided
• As they tend to cause more muscle soreness
• Resistive muscle strengthening is not
recommended in boys with DMD because of
the risk of contraction-induced muscle injuryDr. Asir John Samuel, MPT, PhD, Assoc. Prof. 40

41. Resisted exercise
• Lack of dystrophin increases susceptibility to
muscle cell damage
• Microtears in the muscle cell membrane
increase with muscle contractions and cause
an increase in calcium leak channel activity,
which in turn causes an increase in
intracellular calcium
Dr. Asir John Samuel, MPT, PhD, Assoc. Prof. 41

42. Resisted exercise
• This increase causes calcium-dependent
proteolysis, which eventually leads to cell
death
• Strength training in boys with DMD has been a
subject of controversy
Dr. Asir John Samuel, MPT, PhD, Assoc. Prof. 42

43. Minimizing Spinal Deformity
• Child’s sitting time increases, so does
kyphoscoliosis
• Convexity will likely be toward the dominant
extremity
• Spinal orthoses do not delay the development
of the spinal curve and might increase work of
breathing Dr. Asir John Samuel, MPT, PhD, Assoc. Prof. 43

44. Endurance exercise
• Endurance exercise such as swimming has
been found to be beneficial in mdx mice by
increasing the resistance to fatigue in muscles
by increasing the proportion of type I (slow
oxidative) fibers
• Submaximal endurance training such as
swimming or cycling may be beneficial,
especially in the younger child with DMDDr. Asir John Samuel, MPT, PhD, Assoc. Prof. 44