Duchenne muscular dystrophy (DMD) is a hereditary, degenerative disease of skeletal muscles that was first described in the mid-19th century. It is caused by an abnormal gene on the X chromosome that results in a lack of the protein dystrophin. DMD affects only males and is characterized by progressive muscle weakness and wasting that begins in early childhood. Affected boys experience difficulty walking and climbing stairs. Over time, additional muscle groups become involved including those of the shoulders, pelvis, and respiratory system. Contractures develop as some muscles weaken faster than others. Without intervention, death usually occurs in the late teenage years due to respiratory or cardiac failure.

1. DMD
Dr. Nawaj M. Pathan(PT)
MPT-Neurosciences
nawaj12@hotmail.com

2. Historical background
• The muscular dystrophies are a group of Progressive,
Hereditary, Degenerative disease of skeletal muscles.
• The word dystrophies should be reserved for the purely
degenerative muscular disease of hereditary type and all the
other progressive diseases of muscle should be referred to as
Myopathies or polymyopathies.
• Following are the criteria's to distinguish other degenerative
diseases are-
 The symmetrical distribution of muscular weakness & atrophy.
 Intact sensations
 Preservations of cutaneous reflexes

3. Historical background
• The isolated cases of muscular dystrophies had been reported
earlier.
• The description was made between myopathic and neuropathic
disease.
• In 1843-44, Mr. Little had described what appears to be in
muscular dystrophies- in his lectures at Royal orthopedic
hospital.

4. • Meryon in 1852 gave first clear description of progressive
weakness & atrophy of muscles in young boys with intact
spinal cord & nerves.
• This fact led him to propose a theory that ‘ Idiopathic disease
of muscles’
• In 1855, the French neurologist Duchenne described the
‘progressive muscular atrophy of childhood 'that now bears his
name.

5. • In 1861 he postulated it as a “hypertrophic paraplegia of
infancy” was recognized as a distinct syndrome, recognized
that the disease was muscular in origin and restricted to males.
• Gowers in 1879 gave a masterful account of 21 personally
observed cases and called attention to the characteristic way in
which such patients arose from the floor (Gowers sign).

6. Etiology
• Over the years there have been no of theories concerning the
pathogenesis of muscular dystrophies as a whole and DMD in
particular.
• Abnormal gene on the X chromosome and of its gene product,
dystrophin is responsible for DMD.
• Mutation of dystrophin is the primary cause of DMD

7. Clinical Features
• Only males are affected.
• Duchenne muscular dystrophy is usually recognized by the
third year of life and almost always before the sixth year.
• They appear to be less active than usual and are prone to falls.
Increasing difficulty in walking, running, and climbing stairs,
swayback, and waddling gait become ever more obvious as
time passes.
• The iliopsoas, quadriceps, and gluteal muscles are involved
initially; then the pretibial muscles get weak.

8. • Enlargement of the calves and certain other muscles is
progressive in the early stages of the disease.
• The enlarged muscles have a firm, resilient (“rubbery”) feel
and as a rule are slightly less strong and more hypotonic than
healthy ones (pseudo-hypertrophy).
• Muscles of the pelvic girdle, lumbosacral spine, and shoulders
become weak and wasted, accounting for certain clinical
peculiarities. Weakness of abdominal and paravertebral
muscles accounts for a lordotic posture and protuberant
abdomen when standing and the rounded back when sitting.

9. • Bilateral weakness of the extensors of the knees and hips
interferes with equilibrium and with activities such as climbing
stairs or rising from a chair or from a stooped posture.
• In rising from the ground, the child first assumes a four point
position by extending the arms and legs to the fullest possible
extent and then works each hand alternately up the
corresponding thigh(Gowers sign)
• In standing and walking, the patient places his feet wide apart
in order to increase his base of support.(“straddles as he
stands and waddles as he walks.”)

10. • Many affected boys have a tendency to walk on their toes as a
consequence of contractures in the gastrocnemeii muscles.
• Weakening of the muscles that fix the scapulae to the thorax
(serratus anterior, lower trapezius, rhomboids) causes a
winging of the scapulae.
• Later, weakness and atrophy spread to the muscles of the legs
and forearms. The muscles that are selectively affected include
the neck flexors, wrist extensors, Brachioradialis, costal part of
the pectoralis major, latissimus dorsi, biceps, triceps, anterior
tibial, and peroneal muscles.

11. • The ocular, facial, bulbar, and hand muscles are usually
spared, although weakness of the facial & sternocleidomastoid
muscles and of the diaphragm occurs in the late stages of the
disease.
• The space between the lower ribs and iliac crests diminishes
due to involvement of the abdominal muscles.
• The hamstring muscles become permanently shortened
because of a lack of counteraction of the weaker quadriceps
muscles.

12. • Similarly, contractures occur in the hip flexors because of the
relatively greater weakness of hip extensors and abdominal
muscles. This leads to a pelvic tilt and compensatory lordosis
to maintain standing equilibrium.
• The consequences of these contractures account for the
habitual posture of the patient with Duchenne dystrophy:
lumbar lordosis, hip flexion and abduction, knee flexion, and
plantar flexion.
• These contractures contribute importantly to the eventual loss
of ambulation.

13. • Scoliosis- develop due to unequal weakening of the
paravertebral muscles
• The tendon reflexes are diminished and then lost as muscle
fibers disappear, the ankle reflexes being the last to go.
• Smooth muscles are spared, but the heart is usually affected
• Various types of arrhythmia may appear, on ECG prominent R
waves are common.

14. Prognosis
• Death is usually the result of pulmonary infections and
respiratory failure and, sometimes, of cardiac decompensation.
• These patients usually survive until late adolescence.
• 20 to 25 % of patients live beyond the twenty-fifth year, last
years of life are spent in a wheelchair; finally the patient
becomes bedfast.

15. Any Questions??????????