Transcript Muscular Dystrophy - Muayad Kadhim's WebSite

Muscular
Dystrophy
Amjad Moiffak Moreden, M.D.
Department of Orthopaedic Surgery
The General Assembly of Damascus Hospital
Ministry of Health
Damascus, Syria
Jun. 26, 2007
Introduction
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Muscular dystrophy (MD) is a group of rare inherited muscle
diseases in which muscle fibers are unusually susceptible to
damage. Muscles, primarily voluntary muscles, become
progressively weaker. In the late stages of muscular dystrophy,
fat and connective tissue often replace muscle fibers. In some
types of muscular dystrophy, heart muscles, other involuntary
muscles and other organs are affected.
The most common types of muscular dystrophy appear to be
due to a genetic deficiency of the muscle protein dystrophin.
There's no cure for muscular dystrophy, but medications and
therapy can slow the course of the disease.
Definition
“muscular dystrophy” (MD) describes a group
of primary genetic disorders of muscle that
often have a distinctive and recognizable clinical
phenotype, accompanied by characteristic, but
frequently not pathognemonic, pathological
features.
Muscular Dystrophy Types and Genes
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Duchenne MD DMD Dystrophinopathy
Becker MD BMD Dystrophinopathy
Emery-Dreifuss MD EDMD
Dominant Emery-Dreifuss MD AD-EDMD
Limb-girdle MD type 1A LGMD1A
Limb-girdle MD type 1B LGMD1B
Limb-girdle MD type 1C LGMD1C
Limb-hirdle MD type 1D LGMD1D
Limb-girdle MD type 1E LGMD1E
Limb-girdle MD type 2A LGMD2A Calpainopathy
Limb-girdle MD type 2B LGMD2B Dysferlinopathy
Miyoshi myopathy MM Dysferlinopathy
Miyoshi-type MD MMD
α-Sarcoglycanopathy SGCA LGMD2D, SCARMD2
β-Sarcoglycanopathy SGCB LGMD2E
γ-Sarcoglycanopathy SGCC LGMD2C, SCARMD1
δ-Sarcoglycanopathy SGCD LGMD2F
Limb-girdle MD type 2G LGMD2G
Limb-girdle MD type 2H LGMD2H
Limb-girdle MD type 2I LGMD2I
Merosin-negative congenital MD
Congenital MD with rigid spine
Fukuyama congenital MD FCMD
Congenital Myopathy (or ?MD)
Facioscapulohumeral MD FSHD
Xp21
Xp21
Xq28
1q11
5q
1q11
p25
6q22
7q
15q15
2p13
2p13
10
17q21
4q12
13q12
5q33
17q11
9q31
19q13-3
6q22
1p35
9q31
12q13
4q35
M.D. Types
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There are nine major types of MD affecting
people of all ages, from infancy to middle age or
later. The two most common types of MD
affect children:
Duchenne muscular dystrophy (DMD)
Becker muscular dystrophy (BMD)
Signs and symptoms
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They vary according to the type of muscular
dystrophy. In general, they may include:
Muscle weakness
Apparent lack of coordination
Progressive crippling, resulting in contractures of the
muscles around your joints and loss of mobility
Many specific signs and symptoms vary from among
the different forms of MD. Each type is different in the
age of onset, what parts of the body the symptoms
primarily affect and how rapidly the disease progresses.
Signs and symptoms
Cont..
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Dystrophinopathies
These types of muscular dystrophies are due to
a genetic deficiency of the protein dystrophin.
Signs and symptoms
Cont..
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Duchenne muscular dystrophy is the most severe form of
dystrophinopathy. It occurs mostly in young boys and is the most
common form of MD that affects children. Signs and symptoms
of Duchenne MD may include:
Frequent falls
Large calf muscles
Difficulty getting up from a lying or sitting position
Weakness in lower leg muscles, resulting in difficulty running and
jumping
Waddling gait
Mild mental retardation, in some cases
Gower's maneuver
Signs and symptoms
Cont..
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Duchenne usually appear between the ages of 2 and 5. It first
affects the muscles of the pelvis, upper arms and upper legs. By
late childhood, most children with this form of muscular
dystrophy are unable to walk. Most die by their late teens or early
20s, often from pneumonia, respiratory muscle weakness or
cardiac complications. Some people with Duchenne MD may
exhibit curvature of their spine (scoliosis).
Becker's muscular dystrophy is a milder form of
dystrophinopathy. It generally affects older boys and young men,
and progresses more slowly, usually over several decades. Signs
and symptoms of Becker's MD are similar to those of
Duchenne. The onset of the signs and symptoms is generally
later, and those affected by Becker's MD usually are able to walk
until at least age 15, and often well into adulthood.
Signs and symptoms
Cont..
Myotonic dystrophy
Also known as Steinert's disease, this form of
muscular dystrophy produces stiffness of muscles and
an inability to relax muscles at will (myotonia), as well
as the muscle weakness of the other forms of muscular
dystrophy.
Although this form of MD can affect children, it
often doesn't affect people until adulthood. It can vary
greatly in its severity. Muscles may feel stiff after using
them. Progression of this form of MD is slow.
Signs and symptoms
Cont..
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Besides myotonia, signs and symptoms of adult-onset myotonic dystrophy may
include:
Weakening of voluntary muscles that control your arms and legs, usually beginning
with the limb muscles farthest from the torso — the muscles of the feet, hands, lower
legs and forearms.
Weakening of head, neck and face muscles, which may result in the face having a
hollow, drooped appearance.
Weakening of muscles involved in breathing and swallowing. Weaker breathing muscles
may result in less oxygen intake and fatigue. Weaker swallowing muscles increase the
risk of choking.
Fainting or dizziness, which may indicate that the disease is interfering with the
conduction of electrical signals that keep the heart rate normal.
Weakening of muscles of hollow internal organs such as those in the digestive tract
and the uterus. Depending on which part of the digestive tract is affected, you may
experience problems with swallowing as well as constipation and diarrhea. Weakness of
the uterine walls may cause problems during childbirth.
Difficulty sleeping well at night and daytime sleepiness, and inability to concentrate
because of the effect of the disease on the brain.
Frontal balding in men.
Clouding of the lenses of the eyes (cataracts).
Mild diabetes.
Signs and symptoms
Cont..
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Rarely, infants have this form of muscular dystrophy,
in which case it's called congenital myotonic
dystrophy. The infant form is more severe, although
infants with myotonic dystrophy don't experience
myotonia. Signs in infants may include:
Severe muscle weakness
Difficulty sucking and swallowing
Difficulty breathing
Cognitive impairment
Signs and symptoms
Cont..
Facioscapulohumeral Dystrophy
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Also known as Landouzy-Dejerine disease, this form involves
progressive muscle weakness, usually in this order:
Face
Shoulders
Abdomen
Feet
Upper arms
Pelvic area
Lower arms
When someone with facioscapulohumeral MD raises his or her
arms, the shoulder blades may stick out like wings. Progression
of this form is slow, with some spurts of rapidly increasing
weakness. Onset usually occurs during the teen to early adult
years.
Signs and symptoms
Cont..
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The other major types of muscular dystrophy
are rare. They include:
Limb-girdle muscular dystrophy
Congenital muscular dystrophy
Oculopharyngeal muscular dystrophy
Distal muscular dystrophy
Emery-Dreifuss muscular dystrophy
Causes
1- X-linked recessive inheritance
pattern with carrier mother
2- Autosomal dominant
inheritance pattern
X-linked recessive inheritance pattern
with carrier mother
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Duchenne and Becker's muscular dystrophies
are passed from mother to son through one of
the mother's genes in a pattern called X-linked
recessive inheritance. Boys inherit an X
chromosome from their mothers and a Y
chromosome from their fathers. The X-Y
combination makes them male. Girls inherit two
X chromosomes, one from their mothers and
one from their fathers. The X-X combination
determines that they are female.
Autosomal dominant inheritance pattern
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Patterns differ for other types of MD
Myotonic dystrophy is passed along in a pattern called autosomal
dominant inheritance. If either parent carries the defective gene
for myotonic dystrophy, there's a 50 percent chance the disorder
will be passed along to a child.
Some of the less common types of muscular dystrophy are
passed along in the same inheritance pattern that marks
Duchenne and Becker's muscular dystrophies. Other types of
muscular dystrophy can be passed on from generation to
generation and affect males and females equally. Still others
require a defective gene from both parents.
Screening and diagnosis
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Blood tests. Damaged muscles release enzymes such as creatine kinase (CK) into the
blood. High blood levels of CK suggest a muscle disease such as muscular dystrophy.
Electromyography. A thin-needle electrode is inserted through your skin into the
muscle to be tested. Electrical activity is measured as you relax and as you gently
tighten the muscle. Changes in the pattern of electrical activity can confirm a muscle
disease. The distribution of the disease can be determined by testing different muscles.
Ultrasonography. High-frequency sound waves are used to produce precise images of
tissues and structures within your body. An ultrasound is a noninvasive way of
detecting certain muscle abnormalities, even in the early stages of the disease.
Muscle biopsy. A small piece of muscle is taken for laboratory analysis. The analysis
distinguishes muscular dystrophies from other muscle diseases. Special tests can
identify dystrophin and other markers associated with specific forms of muscular
dystrophy.
Genetic testing. Blood samples are examined for mutations in the gene that produces
dystrophin. Standard tests examine just the portions of the dystrophin gene
responsible for most cases of Duchenne and Becker's muscular dystrophies. These
tests identify deletions or duplications on the dystrophin gene in about two-thirds of
people with Duchenne and Becker's MDs. The genetic defects responsible for
Duchenne and Becker's muscular dystrophies are harder to identify in other cases of
those affected, but new tests that examine the entire dystrophin gene are making it
possible to pinpoint tiny, less common mutations.
Treatment
There's currently no cure for any form of
muscular dystrophy. Research into gene therapy
may eventually provide treatment to stop the
progression of some types of muscular
dystrophy. Current treatment is designed to help
prevent or reduce deformities in the joints and
the spine and to allow people with MD to
remain mobile as long as possible. Treatments
may include various types of physical therapy,
medications, assistive devices and surgery.
Treatment Cont..
Physical therapy:
As muscular dystrophy progresses and muscles weaken,
fixations (contractures) can develop in joints. Tendons
can shorten, restricting the flexibility and mobility of
joints. Contractures are uncomfortable and may affect
the joints of your hands, feet, elbows, knees and hips.
One goal of physical therapy is to provide regular
range-of-motion exercises to keep your joints as flexible
as possible, delaying the progression of contractures,
and reducing or delaying curvature of your spine. Using
hot baths (hydrotherapy) also can help maintain range
of motion in joints.
Treatment Cont..
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Medications:
For myotonic dystrophy. The medications mexiletine
(Mexitil), phenytoin (Dilantin, Phenytek),
carbamazepine (Tegretol, Carbatrol), quinine and
procainamide (Procanbid, Pronestyl) may be used to
treat the delayed muscle relaxation that occurs in
myotonic dystrophy.
For Duchenne muscular dystrophy. The antiinflammatory corticosteroid medication prednisone
may help improve muscle strength and delay the
progression of Duchenne MD.
Treatment Cont..
Assistive devices:
Braces can both provide support for weakened
muscles of your hands and lower legs 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. If
respiratory muscles become weakened, using a
ventilator may become necessary.
Treatment Cont..
Surgery: ( three approaches: ambulatory, rehabilitative, palliative )
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Surgical release of contractures: Cut through
tendons to relieve contractures (tendon release surgery).
Spinal fusion for scoliosis: Scoliosis in a wheelchairdependent child with MD can become so severe it
causes breathing problems and pneumonia. Having
spine surgery before this happens can preserve
breathing function, lessen back pain and improve sitting
balance. All these factors improve the child's quality of
life. The surgery is recommended when the spinal curve
reaches a certain size (i.e., more than 20 degrees).
Surgical Treatment
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Percutaneous Release of Hip Flexion and Abduction
Contractures and Tendo Calcaneus Contracture.
Open procedure technique
TECHNIQUE:
With the child supine on the operating table, prepare and drape both
lower extremities from the iliac crests to the toes. First flex and then
extend the hip to be released, holding the hip in adduction to place
tension on the muscles to be released; keep the opposite hip in maximal
flexion to flatten the lumbar spine. Insert a no. 15 knife blade
percutaneously just medial and just distal to the anterosuperior iliac
spine. Release the sartorius muscle first, then the tensor fasciae
femoris muscle. Push the knife laterally and subcutaneously—without
cutting the skin—to release the tensor fasciae latae completely. Bring
the knife to the original insertion point and push it deeper to release the
rectus femoris completely. Take care to avoid the neurovascular
structures of the anterior thigh. Next, approximately 3 to 4 cm proximal
to the upper pole of the patella, percutaneously release the fascia lata
laterally through a stab wound in its midportion. Push the knife almost
to the femur to release the lateral intermuscular septum completely.
Now perform a percutaneous release of the tendo calcaneus. Apply
long leg casts with the feet in neutral position and with the heels well
padded to prevent pressure ulcers.
Surgical Treatment Cont..
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Transfer of Posterior Tibialis Tendon to Dorsum of Foot
(posterior tibialis muscle overpull)
TECHNIQUE:
make a 3-cm incision starting medially at the neck of the talus and extending to the navicular. Open
the sheath of the posterior tibial tendon from the distal extent of the flexor retinaculum to the
navicular. Release the tendon from its bony insertions, preserving as much length as possible. Make a
second incision 6 to 8 cm long vertically between the tendo calcaneus and the medial distal tibia. The
tendo calcaneus can be lengthened through the same incision if necessary. Incise the posterior tibial
tendon sheath and pull the distal portion of the tendon through the second operative wound. Make
a third incision 6 cm long lateral to the anterior crest of the tibia and extend it to the superior
extensor retinaculum. Incise the anterior compartment fascia and retract the tibialis anterior tendon
laterally. Carefully incise the interosseous membrane on the lateral aspect of the tibia adjacent to its
tibial insertion for a distance of 3 cm. Enlarge the opening by proximal and distal horizontal cuts,
extending halfway across the interosseous membrane. Pass a curved clamp close to the tibia from
the anterior compartment proximally into the second incision. Keep the curved clamp on the tibia to
prevent injury to the peroneal vessels. After grasping the posterior tibialis tendon and pulling it into
the third incision, inspect the tendon through the second incision to make sure that it has neither
twisted on itself nor ensnared the flexor digitorum longus tendon. Make a fourth incision 3 cm long
on the dorsum of the foot in the region of the middle cuneiform. Incise the periosteum of the
middle cuneiform and expose the central portion of the bone. Drill a hole 5 to 8 mm to insert the
tendon through the middle of the cuneiform. Pass a Kelly clamp subcutaneously from the third
incision to the fourth incision distally to create a subcutaneous tract for the posterior tibialis tendon.
Pull the tendon through the subcutaneous tract with a tendon passer. Holding on to the sutures tied
to the end of the posterior tibialis tendon, pass the tendon into the hole in the middle cuneiform
and pass the sutures through the dorsum of the foot with the aid of straight needles. Release the
tourniquet. Inspect, irrigate, and close the wounds. After the wounds have been closed tie the suture
over a felt pad and button on the plantar aspect on the foot with the foot in a neutral position.
Apply a long leg cast with the knee extended and the ankle in neutral position.
Surgical Treatment Cont..
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Transfer of Posterior Tibialis Tendon to Dorsum of Base
of Second Metatarsal
(posterior tibialis muscle overpull)
TECHNIQUE:
With the patient supine and a tourniquet in place, make a 3-cm incision over the insertion of the
posterior tibialis tendon on the navicular. Open the sheath of the posterior tibialis tendon from the
anterior aspect of the medial malleolus to the navicular. Release the tendon from the bony
insertions, preserving as much length as possible. Make a second incision in the posteromedial calf
in the region of the myotendinous junction of the posterior tibialis tendon. A gastrocnemius
recession can be performed through this incision if necessary, but excessive lengthening of the
triceps surae complex should be avoided to prevent the development of a crouched gait
postoperatively. Open the posterior tibial tendon sheath and pull the tendon through the sheath
into the calf wound. At the myotendinous junction of the tibialis posterior, incise the tendon
transversely halfway through its width. Extend this incision distally to within 0.5 cm of the cut
insertion of the tibialis tendon. Secure the distal aspect of the tendon with a single suture to
prevent the longitudinal cut from extending out to the end of the tendon. This procedure
effectively doubles the length of the posterior tibialis tendon. Make a third incision, 6 cm long
lateral to the anterior crest of the tibia, extending it to the superior extensor retinaculum. Perform
an anterior compartment fasciotomy and retract the tibialis anterior tendon laterally. Incise the
interosseous membrane of the lateral aspect of the tibia for a distance of 3 cm. Take a Kelly clamp
and place it through the anterior compartment wound across the interosseous membrane and into
the deep posterior compartment. Grasp the end of the lengthened posterior tibialis tendon and
bring it through the interosseous membrane into the anterior compartment of the calf . Make
another incision, 2 to 3 cm long, over the base of the second metatarsal. Dissect down to the base
of the second metatarsal and subperiosteally dissect around the base of the second metatarsal
circumferentially. Take the elongated tibialis posterior tendon and tunnel it subcutaneously into the
incision over the dorsum of the second metatarsal. Loop the tendon around the base of the second
metatarsal as a sling and tie it to itself with the appropriate tension on the ankle to hold it into a
neutral plantar flexion and dorsiflexion. Release the tourniquet and inspect the tibial vessels to
make sure that they are not being kinked by the transferred tendon. Irrigate the wounds and close
them in a standard fashion.
Surgical Treatment Cont..
Lengthening of Tendo Calcaneus
(Equinus deformity)
Surgical Treatment Cont..
Scapulothoracic Fusion
(inability to functionally flex and abduct the shoulder )
TECHNIQUE:
Place the patient prone and manually position the scapula at 15
to 20 degrees of external rotation. Make an oblique 12-inch
incision over the medial border of the scapula and transect the
trapezius muscle. Release the rhomboids and levator scapula
from their scapular insertions and elevate the supraspinatus,
infraspinatus, and subscapularis muscles subperiosteally for 2 cm
from the medial border of the scapula. Excise a 2-cm strip of
subscapularis muscles to allow approximation of the scapula to
the thoracic wall. Usually ribs 3 through 7 are exposed
subperiosteally for 2 cm. Pass double 16-gauge Luque wires
subperiosteally under each rib. Use a sharp towel clip to make
holes 1 cm from the medial ledge of the scapular points
corresponding from the wired ribs. Use a burr to decorticate the
posterior surface of the exposed rib margins in the
corresponding points along the anterior surface of the scapula.
Place strips of cancellous allograft taken from the posterior iliac
crest between the denuded ribs and scapula. Tighten the wires
sequentially
Treatment Cont..
Other treatments
Because respiratory infections may become a
problem in later stages of muscular dystrophy,
it's important to be vaccinated for pneumonia
and to keep up-to-date with influenza shots.
THE END
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Dr. Muayad Kadhim
‫ مؤيد كاظم‬.‫د‬