encodes for the protein
dystrophin, found in muscle
cells and some neurons.
Dystrophin provides strength to muscle cells by
linking the internal cytoskeleton to the surface
membrane.
Without this structural
support, the cell membrane
becomes permeable.
In DMD the damage to muscle
cells is so extreme that the
supply of stem cells are
exhausted and repair can no
longer occur.
DMD is a sever progressive X-linked inherited disease
characterized by progressive degeneration of the skeletal
muscle especially those of the shoulder and pelvic griddle.
clinical features
Progressive weakness
Intellectual impairment
Hypertrophy of the calves
Proliferation of
connective tissue
in muscle
A mutation in the gene encoding for dystrophin
protein, which is Xp21 gene.
Due to loss of dystrophin
1-fragile sarcolemma
Which leads to
1-increased osmotic fragility of dystrophic muscles
2-exceesive influx of calcium ions
3-release of soluble muscle enzymes such as Creatine kinase.
4-Necrosis of the muscle cell.
Pathological progression
2-loss of interaction between
the sarcolemma and
extracellular matrix.
3-separation of the
sarcolemma from the
basal lamina.
Which leads to
Difference between BMD and DMD
BMD is milder and has low levels of dystrophin due to
Clinical progression
1-Early
Infancy
Poor head
control
2-Transitional
Toddler
hip weakness
and lordosis
3-9 years
Gower sign and HT of calf.
3-Loss of
Ambulatory
10-14 years
Wheel chair
4-Late
+15 years
Respiratory-cardiac-CNS
complications
Complications of DMD
Cardiac
Arrhythmias
-Cardiomyopathy
Orthopaedic problems
-Joint contractures
-Osteopenia
–because of
immobility but also
secondary to steroid
treatment
-Scoliosis
Infectious
Pulmonary infections
Pulmonary
Respiratory insufficiency with
decreased total lung capacity,
decreased residual lung volume
With an incidence of one in 5,000 boys,
which are 200 per million births.
Investigations
Serum Creatine Kinase
used to detect i (myositis) or
(myopathies) such as muscular
dystrophy
A high CK generally indicates
that there has been some recent
muscle damage but will not
indicate its location or cause.
to detect if Ahmad has any
muscular disorder since he already
had muscle weakness and pain.
Electromyography
is a diagnostic procedure to assess the
health of muscles and the nerve cells
that control them (motor neurons).
EMG translates electrical signals
of our muscles into graphs, sounds
or numerical values
The doctor has ordered electromyography
because Ahmad was complaining of muscle
tenderness and weakness.
Thyroid Function Test
blood tests that
determine the function
of the thyroid gland
by measuring : TSH
, thyroid-stimulating
hormone (TSH) thyroid
hormone levels, thyroxine
(T4) and triiodothyronine (T3)
Since Ahmad had muscle weakness,
the doctor wanted to check thyroid
hormones levels since they affect
many conditions in our bodies
including muscle strength
Western Blot
to detect and analyze proteins
Since the doctor was suspecting DMD, he
wanted to make sure that the dystrophin
enzyme is absent .Compared it with BMD to
see how BMD is a milder form that has low
dystrophin
Muscle Biopsy
Shows myopathic changes
such as; connective tissue
proliferation, scattered
degenerating and
regenerating myofibres
Management
Pharmacological
Corticosteroids such as
prednisone, can help improve
muscle strength
Heart medications, such as
angiotensin-converting enzyme (ACE)
inhibitors or beta blockers, if muscular
dystrophy damages the heart.
For controlling the
asthma
exacerbation
Albuterol is used.
Non pharmcological
Physical and
occupational
therapy
Gene therapy
Stem cell
Prognosis
death occurs usually at about 18-20yrs of age
The causes of death
Respiratory failure
Heart failure
Pneumonia
Aspiration
Airway obstruction.
dystrophy leads to progressively worsening disability
Metabolic
Glycogenoses: Acid
maltase deficiency
History taking for
muscle weakness
Introduction
Greeting the
patient, insure
privacy
Duration
&Location
progression
Radiation
Quality (Pain Scales
/questionnaire) &
Quantity
Aggravating
factors
&Alleviating
factors
Associated symptoms
History of medication
Family history
Muscle Strength Scale
Neurological Examination of lower limb
Motor system
Fasciculations and
muscle wasting
Tone
Clonus
Power at
hip, knee,
ankle, and
tarsal joints
Coordination
Heel–shin test
Toe–finger test
Sensory System
Dermatomes
The
superficial or
cutaneous
reflexes
Gait
Gait Cycle
stance phase
begins with
heel strike
and ends
with push
off from the
forefoot
swing phase
begins after push
off when the toes
leave the ground
and ends with the
heel strike.
Forward flexion of the trunk early in the
stance phase. Compensates for
inadequacy of the knee extensors.
Anterior trunk bending
Backward movement of the
trunk early in the stance phase.
Compensates for inadequacy of
hip extensors.
Posterior trunk bending
(Gluteus maximus (Lurch)
gait)
The legs are not different in length when
measured but are unable to adjust to the
appropriate length during the gait cycle.
The long limb is circumducted
during the swing phase.
Circumduction may also be used
to advance the swinging leg in the
presence of weak hip flexors
Swing-out gait (circumduction gait)
The pelvis is lifted on the side
of the swinging leg (normal) by
contraction of the spinal
muscles and the lateral
abdominal wall.
Hip hiking
Exaggerated hip and knee
flexion to lift the foot higher
than usual for increased
ground clearance.
Steppage gait
Going up on the toes of the stance
phase leg. Results in exaggerated
upward movement of the trunk.
Seen in Weak hamstring
Vaulting
A rhythmic
disturbance in which
as short a time is
possible is spent on
the painful limb, and a
correspondingly
longer time is spent
on the pain-free side.
Antalgic gait
In parkinsonism
Shuffling gait
A rhythmic disturbance
where the timing alters
from one step to the next.
Also occurs in drunk
people.