Muscular Dystrophies Flashcards
(106 cards)
1
Q
A group of ___ diseases that cause ___ muscle ___.
A
genetic
progressive
degeneration
2
Q
___ and ___ Muscular Dystrophy are the most common
A
Duchenne
Becker
3
Q
Caused by a mutation in the ___ gene which is located on the ___
A
dystrophin
X-chromosome
4
Q
Duchenne Muscular Dystrophy
Prevalence:
A
1.7 to 4.2 per 100,000 births
1 in 3500 male births
Early childhood onset
5
Q
Becker Muscular Dystrophy
Prevalence:
A
1.6 per 100,000 births
1 in 20,000 male births
Late childhood or early adolescent onset
6
Q
Diagnosis typically between:
A
3-5 years of age
7
Q
DMD Common Signs:
A
Gower’s maneuver
Difficulty lifting head
Not walking by 15 months
Difficulty with walking, running, stairs
Has calves that look bigger than normal (pseudohypertrophy)
Walks on toes/balls of feet
Walks with chest pointed out (lordosis)
8
Q
Not walking by ___
A
15 months
9
Q
Has ___ that look bigger than normal (pseudohypertrophy)
A
calves
10
Q
Gower’s maneuver =
A
used by children to stand up from the floor due to weak hip and thigh muscles
child starts in a sitting or lying position on the floor
To stand, they:
Roll over to hands and knees
Push up to a squat or kneeling position
Use their hands to “walk up” their thighs to push themselves upright
(because their quads/glutes are too weak to lift their body without help)
11
Q
Gower’s maneuver indicates:
A
Proximal muscle weakness, especially in:
Gluteus maximus
Quadriceps
12
Q
Gower’s maneuver most commonly associated with:
A
DMD
Becker MD
Sometimes seen in limb-girdle muscular dystrophies
13
Q
DMD Diagnosis - process:
A
Patient history and physical exam
Creatine Kinase (CK) level
Genetic testing
14
Q
DMD Pathophysiology =
A
Inheritance: X-linked recessive
Dystrophin is absent or nonfunctional
Sarcolemma becomes fragile and leaky
15
Q
Dystrophin Protein Deficiency =
A
Dystrophin = a structural protein in muscle cells
Normally stabilizes the muscle cell membrane (sarcolemma) during contraction
16
Q
Without dystrophin:
A
Repeated muscle contraction causes microtears
Calcium influx → triggers cell death (necrosis)
Inflammation and fibrosis replace functional muscle tissue with fat and connective tissue (pseudohypertrophy)
17
Q
Progressive Muscle Degeneration =
A
Affects proximal muscles first (hips, thighs, shoulders)
Progresses to:
Trunk
Distal muscles
Respiratory and cardiac muscle
18
Q
Dystrophin found in:
A
Skeletal muscle
Cardiac muscle
Smooth muscle
Brain
Retina
Kidney
🧠 Loss of dystrophin → membrane instability → muscle cell death
19
Q
Impact on brain:
A
Dystrophin is also expressed in the brain.
Cognitive and learning difficulties may occur due to dystrophin abnormalities.
20
Q
Impact on heart:
A
Cardiomyopathy is common.
Leads to decreased cardiac function and risk of heart failure.
21
Q
Impact on lungs:
A
Weakens the diaphragm and respiratory muscles.
Can result in ventilator dependence.
Increases risk for pneumonia.
22
Q
Impact on skeletal muscle:
A
Progressive muscle wasting and weakness.
Muscle is replaced by fat and fibrous tissue.
Results in inflammation, fibrosis, and loss of function.
23
Q
Impact on bones:
A
Bones become brittle and weak, increasing risk of fractures and deformities (e.g. scoliosis).
24
Q
within the first 3 years of life:
A
affected infants and young boys with DMD show measurable deficits in gross and fine motor function
25
by age 5:
prominent muscle weakness is observed
26
by age 10-12:
>70% boys lose ambulation
27
by age 15:
many patients require noninvasive ventilator support at night
28
20+ years:
advanced respiratory and/or cardiac complications lead to mortality
29
Drug Treatments:
Restoring or Replacing Dystrophin
Reducing Inflammation
Improving Muscle Growth
30
Drugs - Restoring or Replacing Dystrophin
Amondys 45
Elevidys
Exondys 51
Viltepso
Vyondys 53
31
Drugs - Reducing Inflammation
Prednisone
Agamree
Emflaza
Vamorolone
32
Drugs - Improving Muscle Growth
Duvyzat
33
Corticosteroids:
delay loss of ambulation
preserve hand-to-mouth function
Side effects: weight gain, growth delay, cataracts, fractures
Emerging gene and exon-skipping therapies are under investigation
34
(DMD) Care Guidelines - 3 parts:
Part 1: Diagnosis and Neuromuscular Management
Part 2: Respiratory, Cardiac, Bone, and Orthopaedic Management
Part 3: Primary Care, Psychosocial, and Transition Planning
35
Part 1: Diagnosis and Neuromuscular Rehab, endocrine, and GI nutritional management
Assess function, strength, and ROM at least every 6 months
Discussion/initiate corticosteroids
Prolongs walking, supine to stand, and hand to mouth function by 2 years
Delays scoliosis and preserves lung function
Side effects – Weight gain, growth delay, cataracts, fracture risk, Cushing syndrome
36
Part 2: Respiratory, Cardiac, Bone Health, and Orthopaedic Management
Respiratory support (e.g., cough assist, non-invasive ventilation)
Cardiac monitoring (routine ECG and echo; treat cardiomyopathy early)
Bone health: osteoporosis prevention, fracture management
Orthopedic care: scoliosis, contractures, standing support
37
Part 3: Primary Care, Emergency Management, Psychosocial Care, and Transition Planning
Routine preventive care (vaccines, growth monitoring)
Emergency preparedness (anesthesia and corticosteroid stress dose protocols)
Psychosocial care (mental health, behavioral support)
Transition to adult care (vocational support, palliative planning)
38
REHABILITATION MANAGEMENT =
Standardized multidisciplinary assessments at least every 6 months
Provide PT, OT, SLP based on the needs of the individual
Prevent contractures, overexertion, and falls
Provide orthoses, equipment, and mobility devices
39
ORTHOPEDIC MANAGEMENT =
Assess range of motion at least every 6 months
Consider serial casting or Achilles tendon lengthening
Monitor for scoliosis every year, then every 6 months once non-ambulatory
Consider spinal fusion or growing rod
40
neuromuscular management
Stage 1: At Diagnosis
Multidisciplinary team leads care and initiates genetic counseling
Immunization schedule checked and completed
Discuss corticosteroid therapy
Refer female carriers to cardiology for assessment
41
neuromuscular management
Stage 2: Early Ambulatory
Continue multidisciplinary care and support
Begin functional and strength assessments every 6 months
Initiate corticosteroids if not already started
42
neuromuscular management
Stage 3: Late Ambulatory
Ongoing monitoring of function, strength, ROM every 6 months
Continue corticosteroid management
43
neuromuscular management
Stage 4: Early Non-Ambulatory
Same ongoing care; adapt care plan for wheelchair mobility and function
44
neuromuscular management
Stage 5: Late Non-Ambulatory
Focus shifts toward:
Managing complications
Preserving quality of life
Supporting navigation of end-of-life care
45
rehab management
Stage 1: At Diagnosis
Comprehensive multidisciplinary assessment
Begin PT, OT, and SLP interventions based on individual needs
Focus on early contracture prevention, safe activity, energy conservation, orthotic/equipment needs, and school supports
46
rehab management
Stage 2: Early Ambulatory
Continue regular assessments every 6 months
Ongoing tailored treatments from rehab team
Emphasize:
Contracture and fall prevention
Appropriate physical activity
Energy conservation
Orthoses and adaptive equipment
47
rehab management
Stage 3: Late Ambulatory
Maintain all previous interventions
Begin focus on:
Transition planning
Mobility device introduction
Pain and fracture management
48
rehab management
Stage 4: Early Non-Ambulatory
Expand rehab to include:
Wheelchair/seating systems
Supported standing devices
Assistive technologies
Advocacy for participation and adulthood planning
49
rehab management
Stage 5: Late Non-Ambulatory
Continuation and adjustment of all supportive measures
Emphasis on:
Maximizing independence and quality of life
Participation in life roles
Self-actualization
50
ortho management
Stage 1: At Diagnosis
ROM Assessment: Every 6 months
Surgery Referral: Only if necessary (rare)
51
ortho management
Stage 2: Early Ambulatory
Continue ROM assessments
Monitor for scoliosis: Annually
Surgical consideration: Possible foot or Achilles tendon surgery to enhance gait (case-by-case basis)
52
ortho management
Stage 3: Late Ambulatory
Maintain scoliosis monitoring and evaluate ongoing surgical needs
53
ortho management
Stage 4: Early Non-Ambulatory
Scoliosis: Monitor every 6 months
Surgical planning: Consider foot positioning for optimal wheelchair alignment
54
ortho management
Stage 5: Late Non-Ambulatory
Spinal fusion: Initiate posterior spinal fusion in select scenarios
Continue optimizing wheelchair posture via foot support/interventions
55
Highlighted Tests and Measures for Ambulatory Patients:
North Star Ambulatory Assessment (NSAA)
Timed Function Tests
56
North Star Ambulatory Assessment (NSAA):
Gold standard for ambulatory children with DMD
Designed specifically for ambulant boys with Duchenne Muscular Dystrophy (DMD)
Age Range: ~4–13 years
17-item scale that assesses gross motor function (e.g. standing, walking, rising from the floor).
Scoring: Each item scored 0 (unable), 1 (compensatory), or 2 (typical); total score = 34.
Takes 10-20 min to administer
57
NSAA Prognostic Indicators:
A score ≥ 18 indicates walking for 2+ more years
A score of 13 indicates walking for ~24 more months
A score of 9 indicates walking for ~12 more months
58
Timed Function Tests:
Includes 10-meter walk/run, 4-stair climb, and supine-to-stand — measures speed and functional ability
59
Non-Ambulatory Tests and Measures:
Egen Klassifikation Scale
Performance of Upper Limb (PUL)
Brooke Upper Extremity Scale
60
Tests and Measures Across Both Groups:
Hand-held dynamometry – Strength
Active and Passive ROM
Pulmonary Function Testing
61
Tracks functional decline or improvement; responsive to disease progression and intervention (like corticosteroids).
North Star Ambulatory Assessment (NSAA)
62
Timed Function Tests (TFTs):
Use: Measures speed-based functional tasks.
Time for 4 stair climb
Time to rise from floor
Time for 10M walk/run
6MWT
Scoring: Measured in seconds; lower time = better performance.
63
Predictive of loss of ambulation and disease progression.
Timed Function Tests (TFTs)
64
Egen Klassifikation Scale (EK):
Use: Assesses functional abilities in non-ambulatory individuals with neuromuscular disease.
Scoring: 10 items scored 0–3; higher score = more disability
65
Performance of Upper Limb (PUL):
Use: Developed for DMD, assessing upper limb function across shoulder, elbow, and wrist/hand domains.
Versions: PUL 1.2 (commonly used), PUL 2.0 (revised version)
Scoring: Max score = 42; higher score = better function
66
Brooke Upper Extremity Scale:
Use: Classifies upper limb function in DMD.
Scale: 1 (full shoulder use) to 6 (no hand function)
67
Monitors function in later stages, particularly wheelchair-bound DMD patients.
Egen Klassifikation Scale (EK)
68
Tracks gross changes in UE over time.
Brooke Upper Extremity Scale
69
Sensitive to changes over time, especially in non-ambulatory individuals.
Performance of Upper Limb (PUL)
70
Hand-Held Dynamometry:
Use: Measures muscle strength in key groups (e.g., quads, biceps).
Application: Objective data to monitor strength over time or with treatment.
71
Active and Passive ROM:
Use: Measures joint mobility, important for identifying contractures.
Clinical Application: Helps in planning stretching, splinting, and positioning interventions.
72
Pulmonary Function Testing:
Use: Vital capacity, MIP/MEP, peak cough flow.
Application: Key in monitoring respiratory decline and timing of ventilatory support.
73
Timed Functional Measures used in DMD = all predictors of loss of ambulation within ___
6-12 months
74
4 Stair Climb =
Risk threshold: > 8 seconds
Why it matters: Slower stair climbing reflects significant proximal muscle weakness.
75
Time to Rise from Floor =
Risk threshold: > 30 seconds or need to use furniture
Why it matters: One of the earliest indicators of functional decline in DMD. Reflects core and lower limb weakness.
Often where Gower’s Sign is seen.
76
10 Meter Run/Walk =
Risk threshold: > 12 seconds
Why it matters: Reflects gait speed and endurance. Delays here suggest declining ambulatory function.
77
6 Minute Walk Test (6MWT) =
Risk threshold: < 350 meters
Why it matters: Global measure of endurance and cardiorespiratory capacity. A strong predictor of progression toward non-ambulatory status.
78
a functional scale used specifically for ambulant children with Duchenne Muscular Dystrophy (DMD)
North Star Ambulatory Assessment (NSAA)
79
DMD/BMD Care Considerations: Treatment Interventions
Passive and Active Stretching
Strengthening Exercises
Breathing Exercises
Physical Fitness and Activity
Equipment Needs
80
Passive and Active Stretching =
Goal: Prevent or delay contractures; increase range of motion (ROM)
Frequency: Home stretching 4–6x/week
81
Strengthening Exercises =
Recommended:
Submaximal, aerobic (e.g., biking, swimming)
Use RPE to guide effort — moderate intensity
***Avoid:
High-resistance, eccentric exercises, and overexertion
If soreness persists 24–48 hrs, activity was too intense
82
Breathing Exercises =
Purpose: Maintain respiratory strength
Teamwork: Collaborate with respiratory or speech therapy
83
Physical Fitness & Activity =
Goal: Promote stable weight and function
Best choice: Low-impact aerobic (e.g., aquatics)
84
Equipment Needs =
Monitor & support use of orthoses and assistive tech:
Examples: Wheelchair, bath equipment, Hoyer lift, hospital bed
85
Staging:
early
transitional
late
86
Early Stage Interventions:
Stretching: Daily passive stretching to prevent contractures
Night Splinting: Use of AFOs or elbow/wrist splints overnight to maintain joint range.
School Modifications – 504 Plan: Early advocacy for academic accommodations (e.g., extra time, rest breaks, mobility access).
Strength Activities
Parent/Child Education: Counseling on disease progression, energy conservation, and home routines.
Aquatics: Promotes aerobic activity without joint strain—ideal for early-stage fitness.
87
prone-to-contracture muscles:
(e.g., hip flexors, hamstrings, gastrocs).
88
Strength Activities:
Submaximal and low-resistance, focusing on function and avoiding fatigue or eccentric overload
89
Muscles Commonly Affected Early in DMD:
Gluteals (Hip extensors):
Early weakness → compensatory lumbar lordosis and anterior pelvic tilt
Quadriceps:
Progressive weakness impacts stair climbing and standing from the floor (e.g., Gower’s sign)
Hamstrings:
Prone to tightness → knee flexion contractures if not stretched
Gastrocnemius/Soleus (Calf muscles):
Lead to toe walking and ankle plantarflexion contractures
Triceps:
Upper limb extension strength loss—impacts activities like pushing or reaching
Finger flexors:
Can develop tightness over time with loss of upper limb mobility
90
Transitional Stage Interventions:
Activity and Respiratory Exercise
Aquatic Exercise
Transfer Education
Home Accessibility
UE Strengthening
Post-Orthopedic Intervention
91
Activity and Respiratory Exercise =
Maintain endurance and reduce deconditioning
Use of spirometry or incentive spirometers to preserve pulmonary function
92
Aquatic Exercise =
Excellent low-impact option to:
Preserve joint mobility
Support weight and allow easier movement
Promote cardiovascular and respiratory health
93
Training in safe transfers to/from:
Chair to bed
Toilet/shower
Wheelchair (if needed)
May include caregiver instruction
94
UE Strengthening:
Use of functional tasks or gravity-reduced exercise
Avoid overexertion (no eccentric or high-resistance)
95
Post-Orthopedic Intervention:
Rehab after tendon lengthening or spinal fusion (if scoliosis progresses)
Emphasis on maintaining ROM and function
96
Late Stage Interventions:
Equipment
Respiratory management
Aquatic exercise
Pain
Palliative Care
Post-op function
97
Late Stage Equipment:
Power wheelchairs with custom seating and tilt-in-space features
Positioning supports to reduce pressure sores
Standing frames, mobility scooters, and hospital beds
Environmental controls and adaptive switches
98
Late Stage Respiratory Management:
Collaborate with respiratory therapists
Assist with breathing exercises, chest physiotherapy, and cough assist devices
May need non-invasive ventilation (e.g., BiPAP)
99
Late Stage Aquatics:
Gentle range of motion, relaxation, and social participation
Avoid overexertion—goal is comfort and movement, not strengthening
100
Palliative Care:
Emphasize comfort, dignity, and family goals
PT may aid in positioning, respiratory comfort, and gentle mobility
101
Early Stage Key indicators:
(typically ages 2–6)
Ambulatory (walking independently)
Mild delays in gross motor milestones
May show Gower’s sign (using arms to “climb up” from floor)
Toe-walking or frequent falls
Weakness mostly in proximal muscles (glutes, quads, triceps)
102
Transitional Stage Key indicators:
(typically ages 6–12)
Still ambulatory but increasing difficulty
May need orthotics or manual wheelchair for fatigue
Difficulty with stairs, rising from the floor, or walking long distances
Beginning to need help with transfers
103
Late Stage Key indicators:
(typically teens and beyond)
Non-ambulatory
Full-time wheelchair use
Respiratory decline, possible need for BiPAP/ventilation
Possible scoliosis post-op or spinal fusion
Arm weakness, contractures, pain, decreased endurance
104
DMD and BMD are caused by a mutation in the ___ gene
dystrophin
105
The North Star Ambulatory Assessment and timed functional tests are used frequently to predict:
when the child will transition to being non-ambulatory
106
Our role is to:
promote independence as long as possible
maximize functional outcomes
minimize complications due to muscle weakness
