muscular dystrophy(spedforpehm)
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Muscular Dystrophy
Any of a group of progressive muscle disorders caused by a
defect in one or more genes that contro
l muscle functionand characterized by gradual irreversibl
e wasting of skeletal muscle
genetic disorder that weakens themuscles that help the body move.
Also called myodystrophy.Causes and Classificatons
Duchenne muscular dystrophy andBecker muscular dystrophy are caused
by mutations in the dystrophin gene
Limb-girdle muscular dystrophies arecaused by mutations in other genes.
Dystrophin
This protein is located primarily inskeletal and cardiac muscle
it helps stabilize and protect musclefibers
Muscle cells without enough of thisprotein become damaged as muscles
repeatedly contract and relax with use.
The damaged fibers weaken and die
over time, leading to the muscle
weakness and heart problems
characteristic of Duchenne and Becker
muscular dystrophies.
Charactheristics
The Duchenne and Becker types ofmuscular dystrophy are two related
conditions that primarily affect skeletal
muscles, which are used for movement,and heart (cardiac) muscle. These forms
of muscular dystrophy occur almost
exclusively in males.
Both the Duchenne and Becker forms ofmuscular dystrophy are associated with
a heart condition called
cardiomyopathy
Males with Duchenne musculardystrophy typically live into their
twenties, while males with Becker
muscular dystrophy can survive into
their forties or beyond.
Duchenne muscular dystrophy
muscle weakness tends to appear inearly childhood and worsen rapidly
Affected children may have delayedmotor skills, such as sitting, standing,
and walking.
usually wheelchair-dependent byadolescence
mutations that prevent the productionof any functional dystrophin tend to
cause Duchenne muscular dystrophy.
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Becker muscular dystrophy
usually milder and more varied In most cases, muscle weakness
becomes apparent later in childhood or
in adolescence and worsens at a much
slower rate.
Mutations that lead to an abnormalversion of dystrophin that retains some
function usually cause Becker muscular
dystrophy
Limb-girdle muscular dystrophy
is used to describe these disordersbecause the muscles most severely
affected are generally those of the hips
and shouldersthe limb girdle muscles.
The age of onset is usually between 10and 30
Both genders are affected equally When limb-girdle muscular dystrophy
begins in childhood the progression
appears to be faster and the disease
more disabling
When the disorder begins inadolescence or adulthood the disease is
generally not as severe and progresses
more slowly.
Diagnosis
A muscle biopsy (the removal and examof a small sample of muscle tissue)
DNA (genetic) testing Electromyography or nerve conduction
tests (which use electrodes to test
muscle and/or nerve function)
Treatments and drugs
MedicationsCorticosteroids, such as prednisone,
may help improve muscle strength and
delay the progression of certain typesof muscular dystrophy. But prolonged
use of these types of drugs can weaken
bones and increase fracture risk.
TherapyRange-of-motion exercises. One goal
of physical therapy is to provide regular
range-of-motion exercises to keep
joints as flexible as possible.
Mobility aids. Braces can provide support
for weakened muscles and help keep
muscles and tendons stretched and flexible,
slowing the progression of contractures.
Other devices such as canes, walkers and
wheelchairs can help maintain mobility and
independence.
Breathing assistance. As respiratory
muscles weaken, a sleep apnea device may
help improve oxygen delivery during the
night. Some people with severe muscular
dystrophy may need to rely on a ventilator
a machine that forces air in and out of
their lungs.
Surgical and other proceduresSurgical remedies are an option for
several of the problems common to
muscular dystrophy, such as:
Contractures. Tendon surgery can loosen
joints drawn inward by contractures.
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Scoliosis. Surgery may also be needed to
correct a sideways curvature of the spine
that can make breathing more difficult.
Heart problems. Some people who haveheart problems related to muscular
dystrophy may be helped by the insertion of
a pacemaker, which prompts the heart to
beat more regularly.
Prognosis
Becker muscular dystrophy(BMD) is aless severe variant of Duchenne
muscular dystrophy and is caused by
the production of a truncated, but
partially functional form
of dystrophin.Survival is usually into old
age. Affects only boys (with extremely
rare exceptions)
Duchenne muscular dystrophy(DMD) isthe most common childhood form of
muscular dystrophy, it generally affects
only boys (with extremely rare
exceptions), becoming clinically evidentwhen a child begins walking. By age 10,
the child may need braces for walking
and by age 12, most patients are
confined to a wheelchair. Patients
usually die around age 25, but this
depends from person to person
Limb-girdle muscular dystrophyis alsocalled LGMD. Affects both boys and
girls. LGMDs all show a similardistribution of muscle weakness,
affecting both upper arms and legs.
Many forms of LGMD have been
identified, showing different patterns of
inheritance (autosomal recessive vs.
autosomal dominant). In an autosomal
recessive pattern of inheritance, an
individual receives two copies of the
defective gene, one from each parent.
The recessive LGMDs are more frequent
than the dominant forms, and usually
have childhood or teenage onset. The
dominant LGMDs usually show adult
onset. Some of the recessive forms
have been associated with defects in
proteins that make up the dystrophin-
glycoprotein complex.Though a person
normally leads a normal life with some
assistance, in some extreme cases,
death from LGMD occurs due to
cardiopulmonary complications
Educational Implications
In Primary School the mainconsiderations are around mobility and
independence.
In PE pupils should be encouraged toaccess as many physical activities as
possible to use the full range of
movements for as long as possible.
Physiotherapists can provide help andsupport for PE lessons.
Pupils will tire easily - monitor fatigue /look for patterns in school week.
Because of increasing weakness in theshoulder girdle muscles, the child
should not be pulled up by the hands or
from under the arms.
Use of ICT early on to establish skillsbefore they are required.
Extra time / scribe during tests /examinations