Muscle Dystrophies and Spinal Muscle Atrophy Flashcards
Muscular Dystrophy
- Definition: group of hereditary myopathies
- Characteristics:
- Progressive muscle weakness, deterioration, destruction, and regeneration of muscle fibers
- Muscle fibers gradually replaced by fibrous and fatty tissues
- Types
- Beckers dystrophy
- Myotonic dystrophy
- Limb girdle dystrophy
- Facioscapulohumeral dystrophy
Congenital/myotonic muscular dystrophy
birth
dominant
Typically slow with significant intellectual impairment
Duchenne’s Muscular Dystrophy
- Incidence
- One of the most prevalent and disabling types of MD
- Between 1/3500 male births
- Prognosis
- Mortality usually due to respiratory or cardiorespiratory insufficiency
- Many are surviving into their 30s
- New challenges for therapy, education, and vocation
Etiology Duchenne’s Muscular Dystrophy
- Sex linked recessive disorder
- Abnormality on X chromosome at band Xp21
- Results in a disorder of encoding dystrophin and dystrophin associated proteins (DAP)
- Dystrophin acts as an anchor in the intracellular lattice to enhance tensile strength
- If dystrophin is absent from the muscle 🡪 fragility in the muscle membrane during muscle contraction + relative muscle hypoxia as a result of an aberrant vascular response to exercises
- Early breakdown of muscle fiber plasma membrane
Duchenne’s Muscular Dystrophy Characteristics
- Creatine kinase is elevated early in the disease
- Present at birth long before symptoms are present
- Muscle biopsy shows degeneration with loss of fibers, variation in fiber size, and a proliferation of connective and adipose tissue
Duchenne’s Muscular Dystrophy: Clinical Presentation
- Insidious onset
- May be misdiagnosed
- Early symptoms
- Reluctance to walk/run at appropriate ages
- Falling
- Difficulty with stairs
- Toe walking
- Clumsiness
- Pseudohypertrophy
- Gastroc
- Deltoids
- Quads
- Forearm extensors
- Proximal muscles weak early on
- Weakness of hip and knee extensors early
- Gower’s sign
- Initial weakness of the neck/trunk flexors, hip extensors, and interscapular muscles
- Intellectual impairment
- Emotional disturbance
- With progression
- Exaggerated lordosis
- Wide BOS
- Waddling gait
- ITB contracture
- Heel cord contracture
- Loss of unassisted ambulation at ages 9-10
Duchenne’s Muscular Dystrophy: Medical Intervention
- Steroids
- Prolong life by 3 years
- Improve isometric UE strength by 60%
- Improve isometric LE strength by 85%
- Improve pulmonary and cognitive function
- Side effects
- Weight gain
- Growth suppression
- Cataracts
- Osteoporosis
- Other interventions
- Myoblast transplant
- Gene therapy
- Cell based replacement therapy
- Creatine
- Improved muscle strength/endurance
- Less joint stiffness
- Surgical interventions
- Muscle releases (Achilles, fasciotomy of TFL/ITB)
- Scoliosis stabilization
Prognostic factors Duchenne’s Muscular Dystrophy
- Timed functional activities closely related to muscle strength and predictive of loss of ambulation
- 10M walk/run time greater than 9 seconds predicts loss of ambulation within 2 years
- Inability to rise from the floor predicts loss of ambulation within 2 years
- 10M walk/run time greater than 12 seconds predicts loss of ambulation within a year
Duchenne’s Muscular Dystrophy: Evidence Based Tests and Measures
- Northstar Ambulatory Assessment
- The Performance of Upper Limb for Duchenne
- Brook Scale
- Vignos Scale
- Egen Klassifikation Scale
Vignos Scale
1-10 scale with 1 being able to walk and climb stairs without assistance and 10 being confined to bed.
Duchenne’s Muscular Dystrophy: PT Role
- Early diagnosis
- Education, referral, and support for the family
- Weight control
- Sleep and respiratory concerns
- B&B concerns
- Goals
- Prolong function
- Prevent contractures/deformities
- Adapt equipment
- Encourage peer and community interaction
- Pain control
- Many experience spasms and pain
- Massage and gentle stretching appear to help
DMD: Interventions for Infancy-Preschool Age
- Characteristics
- May see developmental delay related to weakness
- Mild tightness of the gastroc/TFL
- PT goals
- Family support and education
- Consider daily ROM and night splinting
DMD: Interventions for Early School Age Period Characteristics
- Characteristics
- Limitations in activity more apparent
- Clumsiness
- Falling
- Difficulty with stairs
- Rising to standing/running
- Gait deviations
- Increased BOS
- Compensated Trendelenburg
- Toe walking
- Lordosis with shoulder retraction
- Lack of arm swing
- Limitations in activity more apparent
DMD: Interventions for Early School Age Period
- Family support and education
- Obtain baseline data on ROM/MMT
- Strength and exercise
- Widely accepted that eccentric exercise and immobilization are detrimental
- Key muscles: abdominals, hip ext/abd, knee extensors
- Maintain ROM/flexibility
- May not be able to prevent contractures, but can slow development
- Key muscles: gastrocs, HS, and TFL
- 1-2x daily, 10 reps, 30-60 seconds
- Night splints in combination with daily stretching most effective; can prolong ambulation
- Cycling, swimming, and standing for 2-3 hours daily
- Respiratory function
- Measure RR
- Chest wall excursion
- Coughing
- Secretion clearing
- Spirometry
- Breathing exercises
- Inspiratory muscle training
- Monitor progression
- Consider need for other mobility options (MWC, scooters, PWC)
- Risk for falls if ambulation continues past when it is feasible
- Risk for scoliosis increases once the child is nonambulatory
DMD: Interventions for Adolescent Period
- Impairments
- Considerable deterioration in function
- Loss of walking
- Reliance of powered mobility
- Considerable deterioration in function
DMD: Interventions for Adolescent Period
- UE considerations
- Encourage participation in ADLs as much as possible
- May need adaptive equipment for self feeding
- UE ergometry program
- Focus on maintenance of muscles needed for transfers
- Encourage participation in ADLs as much as possible
- LE considerations
- Gentle stretching (may add hip flexors, long finger flexors, shoulder, elbow, forearm, and wrist musculature)
- Respiratory function
- Position of the spine is crucial: N to slightly extended is best to prevent scoliosis (loads facet joints and prevents rotation and lateral flexion)
DMD: Interventions for Adolescent Period
- Continuation of standing/walking
- Standers strongly encouraged
- Walking programs
- KAFOs with standby assistance
- Bracing/therapeutic walking based on
- Obesity
- Residual muscle strength
- Absence of severe contractures
- Timely application of braces
- Motivation of the family/child
- Surgical correction
- May be necessary to prolong ambulation
- Personal decision
DMD: Interventions for Adolescent Period 2
- Equipment
- Functional mobility
- Stand pivot transfers will be replaced by one or two person lifts / lift equipment
- Sliding board is not appropriate
- UE weakness
- Toilet and shower equipment
- Powered mobility
- Transition from powered scooter to standard power chair
- Needed for use on buses, cars, etc.
- Transition from powered scooter to standard power chair
- Consider a urinal to decrease the need for transfers
- Airflow mattress, egg crate, or memory foam/hospital bed
- Functional mobility
DMD: Interventions for Adults
- Respiratory considerations
- After age 18, FVC and PEF decline
- Respiratory failure/infection are common contributing factors to death
- Assisted ventilation can prolong life
- Daytime intermittent positive pressure ventilation via mask / nasal cannula
- Nocturnal bilevel positive airway pressure (BiPAP)
- Negative pressure ventilators
- Suctioning
- Breathing exercises
- Postural drainage
3 types of spinal muscle atrophy
infantile werdnig hoffman
intermediate type 2
juvenile Kugelberg-Welander
Spinal Muscular Atrophy etiology and characteristics
- Etiology
- All are autosomal recessive disorders
- Located on chromosome 5
- Affect the anterior horn
- Characteristics
- Wasting and weakness of the muscles
- No sensory disturbances
diagnosis for spinal muscle atrophy
- Clinical presentation
- EMG
- Denervation with fibrillations and a paucity of motor units
- Muscle biopsy
- Muscle ultrasound
- Genetic testing
- Normal cardiac tissue
SMA Special Examinations to Consider
- Clinical presentation
- EMG
- Denervation with fibrillations and a paucity of motor units
- Muscle biopsy
- Muscle ultrasound
- Genetic testing
- Normal cardiac tissue
SMA type 1 onset, characteristics, mortality
- Onset: almost always noted in the first 3 months of life
- Characteristics
- Decreased fetal movement
- Hypotonia but appear alert and responsive
- Difficulty feeding
- Respiratory distress
- Muscle wasting
- Few spontaneous movements
- DTRs decreased or absent
- Mortality
- Limited lifespan
- Respiratory failure
- Dependent on aggressiveness of treatment
Type I: Infantile Werdnig-Hoffman secondary impairments, PT goals
- Secondary impairments
- Scoliosis
- Contractures
- Decreased respiratory capacity
- Fatiguability
- PT goals
- ROM
- Feeding
- Positioning
- Respiratory care
- Select developmental activities
- Assistive technology
- Limited use of prone due to difficulty lifting head, inhibition of abdominal expansion and diaphragmatic depression
- Breathing may become difficult in upright as well
SMA type 2 onset, characteristics, goals
- Onset
- Usually diagnosed at 3-6 months of age
- Also affects infants, but not as severely
- Characteristics
- Floppy, slow to develop motor milestones
- Weak trunk/extremities with muscle atrophy
- Few have feeding problems
- Fine extremity tremors
- May or may not learn to walk
- Most require orthotic intervention
- PT Goals
- Encourage stance
- Prevent deformity
- Respiratory interventions
- Adapt play/writing tools
SMA Type III: Juvenile Kugelberg-Welander
- Onset
- Diagnosed between 1 and 10 y/o
- Characteristics
- Slowly progressive weakness
- Mild impairment
- Proximal muscles are usually involved first
- Slowly progressive weakness