MUSCULAR DYSTROPHY Flashcards
MUSCULAR DYSTROPHY
Refers to a group of genetic, hereditary muscle diseases that weaken the muscles that move us
Muscular dystrophies are characterized by
progressive skeletal muscle weakness, defects in muscle proteins and the death of muscle cells and tissue
In some forms, wasted muscles tend to hypertrophy because of connective tissue and fat deposits, giving the visual appearance of muscle strength
Nine Diseases
Duchenne’s Becker’s Limb Girdle Congenital Facioscapulohumeral (FSH) Myotonic Oculopharyngeal Distal Emery-Dreifuss
Pathogenesis
The affected gene in DMD/BMD encodes messenger RNA(mRNA) for the adhesive protein dystrophin that is located in the muscle membrane, the sarcolemma. Muscle membrane lesions play an early role in the pathogenesis of MD, involving skeletal, cardiac, and smooth muscle membranes.
Dystrophin is the protein that
links the muscle surface membrane (sarcolemma) with the contractile muscle protein (actin). Lack of normal dystrophin makes the sarcolemma susceptible to damage during contraction relaxation cycles. Disruption of the muscle membrane and muscle fiber necrosis are initiated by muscle contraction, especially eccentric contraction
Duchenne’s
Progressive neuromuscular disorder; muscle weakness associated with muscle wasting first affecting the muscles of the hips, pelvic area, thighs and shoulder; muscle weakness also occurs in arms, neck and other areas
Duchenne’s Course
Rapidly progressive; loss of walking by 10-12 yrs; death in early teens to mid 30s
Duchenne’s S&S
Gowers’ sign; falls frequently; difficulty climbing stairs; waddling gait (proximal muscle weakness); increased lumbar lordosis (due to abdominal and hip extensor weakness); toe walking due to contracture of posterior calf musculature and weakness of ant. tibial, peroneal and prox. muscles; pseudohypertrophy of tongue and calf muscles (enlarged muscle tissue is replaced by fat and connective tissue); muscle contractures of Achilles tendon and hamstrings; hip abductor weakness (positive Trendelenburg); fatigue; difficulty with motor skills (running, hopping, jumping); higher risk of behaviour and learning difficulties; skeletal deformities (including scoliosis); muscle fibre deformities; comorbities include respiratory, cardiac and GI dysfunction
Beckers
Progressive neuromuscular disorder characterized by slowly progressive muscle weakness and muscle wasting of proximal muscles before the involvement of the distal muscles; primary effects in neck, trunk, pelvis and shoulder girdles
Beckers Course
Slowly progressive; walking maintained past early teens; lifespan until early adulthood
Beckers S&S
Muscle weakness, slowly progressive; toe-walking; Gowers sign; frequent falls; difficulty breathing; non-progressive cognitive function; skeletal deformities (chest and back - scoliosis); contractures (elbow flexors, forearm pronators and wrist flexors in the upper extremity and plantar flexors, knee flexors, and hip abductors in the lower extremity) muscle deformities (pseudohypertrophy); muscle cramps; fatique; heart disease; elevated CPK levels; cardiomyopathy (damage to the heart) - not as common as with Duchenne’s
FSHMD
Is a mild form of muscular dystrophy with weakness and atrophy of facial muscles and shoulder girdle; weakness is asymmetrical
FSHMD Course
Slowly progressive; loss of walking in later life; variable life expectancy
FSHMD S&S
Inability to close eyes; inability to whistle, decreased facial expression, depressed or angry facial expression, difficulty pronouncing the letters, M, B, and P); difficulty working with arms raised, sloping shoulder; scapular winging; hearing loss; abnormal heart rhythm; unequal weakening of biceps, triceps, deltoids, and lower arm muscles; loss of strength in stomach muscles and eventual progression to legs; foot drop; contractures, skeletal deformities and hypertrophy of muscles is uncommon
Treatment
No known treatment can halt the progression of MD
Current therapy remains primarily supportive
Treatment is directed toward maintaining function in unaffected muscle groups as long as possible
Important to remember there is an active muscle degeneration underlying the MDs
Strenuous exercise may facilitate the breakdown of muscle fibres
Strengthening, especially eccentric exercise, is not helpful and may cause more weakness
Contracture management is the focus
Splinting, stretching, casting are mainstays
Both children and adults can benefit from ambulation and pool therapy programs aimed at improving endurance
An exercise program should only produce minimal fatigue, with no post-exercise soreness
The client should be instructed in diaphragmatic, deep breathing exercises
Airway clearance techniques: percussion and postural drainage
