DMD and SMA Flashcards
(65 cards)
1
Q
What causes Duchenne Muscular Dystrophy?
A
mutation in gene that encodes for dystrophin
2
Q
2/3 cases of Duchenne muscular dystrophy are…
A
x-linked, recessive, myogenic disorders
3
Q
1/3 cases of Duchenne muscular dystrophy are..
A
random spontaneous genetic mutations that occur during pregnancy
4
Q
When do males with Duchenne muscular dystrophy typically lose the ability to walk?
A
early teenage years
5
Q
what is the life expectancy of males with Duchenne muscular dystrophy?
A
early 20’s
6
Q
Characteristic of dystrophin:
A
*Protein inside surface of the sarcolemma
* Increases sarcolemma deformability, maintains muscle cell structure and function
* “Shock absorber”: allows muscles to contract and relax
without damage
* Links actin and other support proteins
* Supports muscle fiber strength, reduces stiffness
7
Q
Lack of dystrophin leads to…
A
intolerance of mechanical forces present during muscle contraction
8
Q
Nervous symptoms signs and symptoms of DMD
A
- developmental delay
- motor delay
9
Q
cognition signs and symptoms of DMD
A
- learning disability
10
Q
gastrointestinal signs and symptoms of DMD
A
- dysphagia
- constipation
- reflux
- gastroparesis
11
Q
respiratory signs and symptoms of DMD
A
- respiration insufficiency
- sleep apnea
12
Q
musculoskeletal signs and symptoms of DMD
A
- muscle weakness (Gower’s Signs; proximal to distal)
- fatigue
- muscle cramps
- difficulty walking and climbing stairs
- gait abnormalities
- contractures
- psuedohypertrophy
- lordosis and scoliosis
- neck weakness
13
Q
heart signs and symptoms of DMD
A
cardiomyopathy
14
Q
Calf Muscle Pseudohypertrophy
A
- apparent increase in size of calf muscles due to the replacement of muscle fibers by fat and connective tissue
- frequently one of the first signs of DMD
15
Q
Diagnosing DMD through blood test
A
- Creatine Kinase Levels
- Enzyme which leaks out of damaged muscles
- Elevated CK levels indicate muscle disintegration
- Peak at 10-20x normal value by age 2-3, then fall at ~25% per year as muscle is replaced with fat and fibrotic tissue
16
Q
Diagnosing DMD through genetic testing
A
- Genetic mutation – deletions
- Carrier screening
- Important –> Research trials and medications now are specific to genetic mutation
17
Q
Diagnosing DMD through muscle biopsy
A
- Previously frequently performed, now rare
- Distinguish among different types of muscular dystrophies
18
Q
How else can DMD be diagnosed?
A
by clinical presentation
19
Q
Infancy - Early Childhood: Early Ambulatory Phase
A
- Few impairments, activity limitations or participation restrictions seen
- Delayed onset of ambulation
- 50%: fail to walk until 18 months of age
*Decreased growth velocity –> shorter stature
*Unless there is a family history of DMD, symptoms are not typically noticed (Dx around 4-5/yo)
20
Q
What is the goal of rehabilitation in the early ambulatory phase?
A
Education and support
21
Q
School-aged: Middle Ambulatory Phase
A
- Initial observations: clumsiness, falling, inability to keep up with peers while playing
- difficulty with stairs, standing up from floor (Gower’s sign)
- Fatigue (8-10) –> restrictive pulmonary disease
22
Q
initial gait of school aged (middle ambulatory phase)
A
- increased lateral trunk sweat, increased with running
- Progressive deviations (compensatory to shift center of mass forward and promote stability): increased base of support, compensated Trendelenburg, toe walking for knee stabilization, in-toeing, shoulder/scapular retraction, lack of reciprocal arm swing
23
Q
Contractures likely to occur during school-aged/middle ambulatory phase
A
- plantar flexors
- hip abductors
- hip flexors
24
Q
School - aged/ middle ambulatory phase - PT Examination
A
- Brooke Scale (UE Function)
- Vignos Scale (LE Function)
- PEDI
- School Function Assessment
- Wee-FIM
- North Star Ambulatory Assessment (used in majority of clinical trials)
25
School aged/Middle ambulatory phase timed functional tests
- 10m Walk-Run
- Supine to stand
- 6MWT
- Climbing 4 stairs
26
What else should you test in the middle ambulatory phase (school aged)
- MMT
- Dynamometry (hip/knee extension)
- ROM
- Respiratory Function Testing (chest wall expansion, ability to cough and clear secretions, FVC)
27
Goals of rehabilitation in Middle ambulatory phase (school aged)
- education and support
- baseline and longitudinal examination
- preventative measures to maintain muscle strength and integrity
- contracture prevention
- appropriate exercise/activity
- Support for function and participation
- provision of equipment
28
What is an absolute no no ever never never never never do?
Eccentric exercise or resistance training
29
submax exercise for middle ambulatory phase (school age)
- train abdominals, hip extensors and abductors, knee extensors
- Aerobic: cycling and swimming
30
Training inhalation and exhalation for middle ambulatory phase (school-aged)
- inflation balloons
- blowing through straws
- incentive spirometers
- Goals: slow the loss of vital capacity, decrease the severity of symptoms of colds and pulmonary infections
31
Assistive technology during middle ambulatory phase (school age)
during transition - introduce motorized scooter vs manual wheelchair
32
School-aged: middle ambulatory phase more interventions
- comfortable stretching program (night splinting)
- Monitor scoliosis
33
school aged: middle ambulatory phase: when should you initiate standing program?
prior to loss of ambulation
34
Cessation of ambulation in DMD
- 50% reduction in leg strength
- MMT <3 hip extensors, MMT < 4 ankle DF
35
Four step climb
5-12 seconds: cessation of unassisted walking within 2.4 years
> 12 seconds: cessation of unassisted walking within 1.5 years
36
10MWT Predicting Cessation of ambulation
> 9 seconds and inability to risk from floor = cessation within 2 years
> 12 seconds = cessation within 1 year
37
in Adolescence/Late ambulatory/early non-ambulatory phase there is a significant disability progression as a result of:
- progressive muscle weakness
- development of contractures
38
In Adolescence/Late ambulatory/early non-ambulatory phase there is....
- increased difficulty with transfers and general mobility
- cessation of walking
- must recognize signs that portray changing status
- provision of ADs
39
PT interventions for Adolescence/Late ambulatory/early non-ambulatory phase
- Prolong standing and ambulation
- Caregiver training
- Transfers
- Bed mobility
- Positioning program
- Assistive technology/DME
- Home modifications
40
Interventions for Adulthood/Late Non-Ambulatory phase
- provision of ADs
- breathing exercises, postural drainage, intermittent pressure breathing, CPAP, mechanical ventilation
41
Gold standard medication for DMD
glucocorticosteroids
42
What is spinal muscular atrophy
- Primarily autosomal recessive
- Lower motor neuron disorder (progressive muscle weakness, atrophy, hypotonia/areflexia)
- Loss of anterior horn cells in SC
43
What are survival Motor neurons?
- gene that creates SMN protein, which is essential to maintain the integrity of motor neurons
- SMA = deletions or mutations in both copies of SMN1
- An exotic splicing suppressor (ESS) at position 6 of SMN2 leads to skipping of exon 7
- Results in truncated, non-functional SMN protein
44
SMA Type I
Onset: 0-6 months
Death: <2 years
Do not sit
45
SMA Type II
Onset: 7-18 mo
Death: > 2 years
Usually do not stand
46
SMA Type III
Onset: > 18 mo
Death: Adult
Stands and Walks
47
Features of Type I SMA (Werdnig-Hoffmann)
- 60% of children with SMA
* Severe weakness at birth
* Profound hypotonia
* Frog legged posture
* Hyporeflexia/Areflexia
* Joint contractures
* Suck-swallow difficulties
* Poor head control
* Respiratory Failure
* Belly breathing
* Tongue fasciculations
48
PT MAnagement Type I
- Weakness
- Positioning Program
- Contractures
- ROM exercises
- Respiratory Care
- Interventions
- Improve feeding and swallowing mechanics
49
Type I - Weakness
* Proximal musculature of the neck, trunk, shoulder girdle, and pelvic girdle –
limited anti-gravity movement
Positioning program
50
Type I- Positioning Program
* Wedges, towel rolls and bolsters to avoid supine in the presence of respiratory
distress
* Side-lying to promote play in a gravity eliminated position
* Prone not typically recommended because of the effort/strength required to
right the head
51
Type I- Contractures
* Talipes equinovarus (clubfoot)
* Additional flexion contractures resulting from fetal akinesia (hip, knee, elbow)
* Positional torticollis (muscle weakness vs. shortness)
52
Type I- ROM Exercises
* Promote flexibility and comfort
* Also consider limited strengthening activities (weighted toys)
53
Type I- Respiratory Care
*Typically require intubation/mechanical ventilation
54
Type I- Interventions
*Suctioning
*Assisted coughing
*Postural drainage
*Supported sitting while monitoring spinal alignment
*Use of abdominal binder
*Close monitoring in supported sitting
55
SMA Type II Features
* Progressive proximal weakness/ hypotonia --> LE’s > UE’s
* Postural hand tremor
* Hyporeflexia
* Average/Above average intellect
* Joint contractures
* Scoliosis and restrictive airway disease
56
PT Management - Type II
*Promotion of independent sitting --> Spinal orthoses (TLSO)
*Custom molded back support in wheelchair
*Standing --> If not independent by 16-18 months, include standing program with supine stander to promote WB (reduce fracture risk)
*Ambulation --> Rarely means of primary mobility
57
Type II in School Years - Adaptive Equipment
* Powered mobility with custom molded seat/ back to accommodate to spine deformity
* Consider alternating joystick position to promote postural symmetry
* Power-assist manual w/c
58
Type II - PT Management in School Years
- Adaptive equipment
- ROM exercises (bracing and contracture management
- Respiratory care - Breathing exercises and postural drainage
- nutrition and weight management
59
Type II - PT management transition into adulthood
- continued used of adaptive equipment and contracture management (personal caregiver, vocational rehab)
- respiratory care is priority --> breathing exercises and postural drainage
60
Type III Features
* May have hand tremor
* Mild progressive weakness
* LE’s > UE’s
* Resembles Becker Muscular Dystrophy
61
Type III - Impairments in school years
- difficulty with higher level gross motor kills: transitioning onto/off of floor, stairs, keeping up with peers
- gait deviations: waddling gait more apparent with running, difficulty keeping up with peers
- Exception: UE spared
62
Type III Most common impairments in school years
* Lower extremity weakness
* Postural compensations (Trendelenburg) resulting from weakness, joint contractures (plantar flexors), and occasional scoliosis
63
PT management in school year: Type III
- ROM
- Mod intensity strengthening
- Functional training
- Adaptive equipment (scooter for long community distance)
- orthotic support
64
SMN1 Gene replacement therapy
- deliver new DNA from healthy SMN1 gene via vector
- Children < 2
- One time IV infusion
65
SMN 2 Gene modulation therapy
- Corrects SMN2 mRNA splicing --> SMN2 produces full protein
- Prompts SMN2 to increased protein production
- all ages and all type SMA
- PT provides superior results in pt's taking this drug
