NMD Part 2 Flashcards
what are muscular dystrophies
group of hereditary ms dz that weaken (primarily) skeletal ms of body
what are muscular dystrophies characterized by (3)
- progressive skeletal ms weakness
- defects in ms proteins
- death of ms cells & tissue
what is the prevalence of muscular dystrophies in childhood
comprises largest and most common group of inherited progressive neuromuscular disorders of childhood
what is the genetic inheritance of duchenne muscular dystrophy
x-linked recessive
what is the typical onset of duchenne muscular dystrophy
1-5yo
what is the course of the dz for duchenne muscular dystrophy
rapidly progressive
loss of walking typically by 9-10yo
death in late teens
what are 3 primary s/sx of muscular dystrophies
- insidious onset of ms weakness
- ms fatigue
- exercise intolerance
what are 5 secondary impairments of muscular dystrophies
- contractures
- postural malalignment, including scoliosis
- changes in appetite
- pain
- sleep apnea
what are 4 additional s/sx of muscular dystrophies
- ms cramping/pain
- ms twitching/fasciculations
- ms wasting (atrophy vs pseudohypertrophy)
- hypotonia
why does ms cramping occur in muscular dystrophies
contractile properties of these ms are changed and inefficient and ineffective
where will we expect to see contractures in muscular dystrophies and why
hip flexors & hamstrings
- if dec strength, sitting a lot
gastroc/PF
- lying in supine, gravity pushes into PF
what is the incidence of duchenne’s in males vs females
primarily in males bc linked to X
rare for females to manifest clinical sx
- if they do it’s very mild
what is the pathophysiology of DMD
mutation in dystrophin gene -> 1 or more exons (part of gene) are missing
what is the role of dystrophin in cells
mechanical stabilization of cell membrane
what does the mutation in the dystrophin gene result in
ms cell destruction d/t abnormal or missing dystrophin & its effect on the cell membrane
-> progressive loss of ms contractility d/t destruction of myofibrils
how many cases of DMD are new mutations
1/3
if the mom is a carrier of DMD, what is the risk for her son or her daughter of having DMD
son - 50% chance of inheriting DMD
daughter - 50% chance of being a carrier
- carrier may be mildly affected
what is the inheritance of BMD
x-linked recessive
BMD vs DMD in pathophys
BMD has same gene affected but some dystrophin is present
BMD course of dz compared to DMD
less severe and more slowly progressing than DMD
avg age of sx onset is later than DMD
amb longer (20s-30s) and longer lifespan than DMD
what is one clinical manifestation that is more common in BMD than DMD
cardiac myopathy
what are lab tests used to diagnose both DMD and BMD
CK values (high)
ms biopsies
- detect degen/regen of ms fibers, fibrosis, & fatty infiltrates
blood tests - detect mutation of dystrophin gene
why are blood tests a better option than ms biopsies
ms biopsies - damage ms that is already fragile
what is Gower’s sign
so weak that use hands to walk up legs to push up to stand and then stand up to lumbar lordosis
what is pseudohypertrophy
ms tissue replaced by adipose and collagen
- can create ms/joint contracture
what does neck flexor AG in DMD and BMD look like
significant head lag
what are 3 things that show up in a clinical exam to diagnose DMD and BMD
(+) Gower’s sign
calves - stiff, firm, pseudohypertrophy
motor difficulties - including neck flexor weakness
what is the criteria for ordering CK labs in the diagnostic guidelines for DMD
more than 3 sx over 2 or more categories (motor milestone delay, unusual gait, speech delay)
what are 3 ex of delayed motor milestones seen in DMD
- unable to walk by 18mo
- unable to jump by 2.5yo
- unable to run by 3yo
what are 3 ex of how unusual gait my present in DMD
- tiptoe walking
- frequent falling
- difficulty climbing steps
what are 3 ex of how speech delay may present in DMD
- no words spoken in first 18mo
- unable to speak sentences by 3yo
- any input from speech services (SALT)
what are 3 red flags identified in the diagnostic guidelines for DMD
- enlarged calf ms
- any ms pain/cramps
- any episodes of cola-colored urine
what can cola-colored urine indicate
rhabdomyolysis
what is a consideration with family planning and DMD
not unusual to have more than one boy w this condition in the family
- slower onset, could have another child by time dx the first
why is scoliosis seen in DMD and BMD
as lose trunk musculature, collapse into gravity
what are 3 medical interventions for DMD and BMD
no curative treatment
oral corticosteroids
anti-hypertensives
RNA therapy & exon-skipping
what are indications for oral corticosteroids in DMD and BMD (4)
prolong amb
reduce decline in CP function
reduce risk of scoliosis
improve life expectancy
what is the importance of oral corticosteroids in comparison to other medical interventions of DMD and BMD
SOC in early amb phase
what are 3 side effects of prednisone & defiazacort
- inc appetite and fluid retention
- behavior changes, irritability/outbursts, reduced attention
- reduced bone health - inc risk of fx
why are anti-hypertensives utilized in medical management of DMD and BMD
cardiomyopathy
- more common in BMD than DMD
what is the goal of RNA therapy & exon skippping
inc dystrophin levels
- > alter genetics to have DMD present more like BMD
amb and life expectancy prolonged
how does RNA therapy and exon skipping work
medication is exon specific
- fosters RNA replication to produce dystrophin
who is RNA therapy and exon skipping used in
pts w DMD w specific mutations
what are the preliminary results of RNA and exon skipping
inc dystrophin production
- effects on motor function TBD
what is the timeline progression of DMD in 5 steps
healthy bith
weakness noted 3-5yo
loss of amb by 9-12yo
- initiate use of light wt wc
power wc dependent 12-14yo
death 20-30yo
what is death caused by in DMD
cardiopulmonary complications
as weakness from DMD presents at ages 3-5yo, what are 4 other manifestations also seen
waddling gait
difficulty moving floor>stand
difficulty keeping up w friends
toe-walking
if you see a child w DMD toe-walking what is this likely telling you
gastroc is effected
what are 3 BSF impairments seen in ambulatory years of DMD/BMD
posture
ROM - progressive ms/joint contractures
strength
what does posture in DMD/BMD look like
calf pseudohypertrophy
- pushes them on toes and into lordosis
inc lumbar lordosis
- weak abdominals
scap winging
why are impairments in ROM seen in amb years in DMD/BMD
weakness & ms fibrosis
what ms will have progressive contractures in amb yrs of DMD/BMD (4)
gastroc/soleus
hamstrings
hip flexors
ITB
how do UE ms ROM impairments present in amb yrs of DMD/BMD
early tightness in forearm pronators & long finger flexors
- UE relatively spared
UE contractures will worsen once non-amb
how does strength impairments present in amb yrs of DMD/BMD
UE and trunk preserved longer/more than LEs
what are the 3 main impairments that develop in non-amb yrs of DMD/BMD
postural changes
UE contractures/weakness
pulmonary function decline
what is the importance of keeping pts w DMD/BMD amb as long as possible
large impact on pulmonary function
- and also contractures
how do postural change impairments present in non-amb yrs of DMD/BMD
losing trunk control/strength
- succumbing to gravity
- can see some twisting
what are 2 impairments in non-amb yrs of DMD/BMD that largely impact w/c positioning and how
postural changes
LE contractures
- eg equinovarus, pelvic obliquity
how can UE contracture/strength impairments in non-amb yrs of DMD/BMD
impact ADLs, driving power w/c
what is the incidence of cardiomyopathy in DMD & BMD
DMD: 90% pts exhibit abnormalities in ECG
BMD: more common than in DMD
what are behavior concerns in DMD/BMD (6)
limited attention
difficulties w mental flexibility
difficulties w executive functioning
autism (3-18%)
reactive depression/anxiety
what are multisystem concerns for DMD/BMD
cardiomyopathy
behavior management
GI motility limitations
how does motor skill development present in early childhood & what is it influenced by
still progress in motor skill development BUT:
- clumsy, falls
- difficulty keeping up w same-age peers w running/climbing
- higher level GM skills like single-limb hop may be difficult
- floor to stand transfers present as Gower’s maneuver
influenced by progression of ms weakness prox>distal; LE>UE
how does motor progression present in infancy for DMD
may have mild delay in motor milestones
how does motor progression (ie specific activity limitations) present in elementary to adolescence for DMD
floor to stand - (+) Gowers
amb - dec distance amb
- quick to fatigue/fall
stairs - inc difficulty
overhead activities (dressing, bathing)
- quick fatigue
when do motor skills plateau in DMD
~7yo
how does motor progression (ie specific activity limitations) present in adolescence for DMD & primary means of mobility
loss of amb & independent transfers by ~10-13yo
manual wc w power assist
- progress quickly to power mobility
how does motor progression (ie specific activity limitations) present in early adulthood for DMD
more rapid loss of UE and respiratory function
UE - transition from standard joystick to adapted power
respiratory - transition from BiPap to tracheostomy
why is there a transition to a power wc from manual in DMD
gradual decline in UE ms function
- loss of hand intrinsics
what is the primary manifestation for carriers of DMD/BMD
no s/sx
what are 2 purposes of PT exam in DMD and BMD
- track natural dz progression over time
- track changes w therapeutic and/or medical interventions over time
what is a key consideration with DMD and BMD when it comes to pt education
child might not know they have the dz
- must ask primary caregiver if okay to discuss
what clinical observations are made in the PT exam of DMD and BMD (4)
general age-level mobility skills
- amb/gait
- stairs
- floor-to-stand and reverse
- running, jumping, single leg balance
what are 5 tests/measures used most commonly in DMD
Activity SINGLE TASK:
6MWT
timed testing - 10m walk, STS, Gowers, 4 stairs
Activity MULTIPLE ITEMS:
Northstar amb assessment
Performance of upper limb
Brook Upper Limb Scale
what test/measure used in DMD is specific just for MD
the performance of upper limb
what two tests/measures assess upper limb function in DMD/BMD
performance of upper limb (PUL)
brooke upper limb scale (screening tool)
what are 2 timed function tests used in DMD and BMD
timed floor to stand
timed up/down 4 steps
what are 2 timed walk & run tests in DMD and BMD
6M
10M
what 6MWT result is predictive of greater functional decline
baseline 6MWT <350m
how do 6MWT times in DMD compare to norms w TD
until 7yo - DMD distance inc w age/growth in TD
- DMD distance <80% of TD
7-8yo
- DMD distance plateaus, then declines linearly w age
- TD - inc w age
what does research say ab the results of timed function tests in DMD and how can this information be utilized
expect decline in function related to amb
can use outcome tests to get a sense of when will lose ability to amb and plan ahead
what is the purpose of the North Star Ambulatory Assessment (NSAA)
measure functional motor abilities in amb children w DMD
- intended to be more clinically meaningful vs MMT
what does a total score >18 on the NSAA indicate
lower risk of losing ambulation in next 2yrs
Brooke UE functional rating scale vs PUL
Brooke - very functional based, screening tool
PUL - specific to MD
what does the Brooke UE functional rating scale assess
grades UE function, reflecting prox to distal strength
what do higher scores on the Brooke UE functional rating scale indicate
less function
what does the PUL assess
looks at strength/control at shoulder, elbow, and hand
what values at what age have been associated with greater functional decline in amb within 12mo (5)
at 7yo
- 6MWT <325m
- time to stand >30sec
- time to climb 4 stairs >8sec
- 10M walk/run >10-12sec
- NSAA raw score <9pts
what are the 3 main interventions that PT provides
- prevention of contracture and deformity
- splinting/bracing
- exercise and activity
what 3 spots are prevention of contracture and deformity PT interventions focused on initially
gastrocs
hip flexors
hamstrings
when does prevention of contracture and deformity start
young age
what are 2 types of interventions that work to prevent contracture and deformity
1-2x ACTIVE daily ROM; gentle PROM
static stretch
what is a concern and consideration with doing PROM as an intervention to prevent contractures/deformities
potential mechanism of damage
- important to do it gently
what are 3 interventions employing static stretch to prevent contracture and deformity
prone positioning
night splints
serial casting
why does prone positioning help to prevent contractures
gets you into hip ext and gravity lengthens hamstring
- doesn’t help gastrocs but addresses other high risk areas (hip flexors, hamstrings)
what evidence is out there for the use of night splints to prevent contractures
combined intervention of splint & ROM is more effective in slowing contraction and a longer duration of amb
what evidence is out there for the use of serial casting to prevent contractures
effectiveness in ambulatory boys in improving DF w no interference in function
what is the window of effectiveness for casting
fixed PF contracture 15-20deg
what is the goal of splints and bracing
to improve/maintain ROM
what is one consideration of splints/bracing
likely will not aide in amb
- may inhibit gait d/t prox weakness
why would we be okay with a pt w MD toe walking
toe walking is an effective compensatory strategy for prox weakness
when is likely the most optimal time for wearing splints
at night for a sustained stretch
what are DMD and BMD pts at a high risk for
rhabdomyolysis
what is rhabdomyolysis
rapid breakdown of skeletal ms tissue d/t mechanical, physical or chemical traumatic injury
what can rhabdomyolysis result in
acute renal failure
fatal heart arrhythmias
what is the pathology behind rhabdomyolysis that can lead to cola colored urine
when ms proteins released into blood, one of these proteins (myoglobin) can precipitate in kidneys which spills into the urine
how can rhabdomyolysis cause acute renal failure
if massive skeletal ms necrosis occurs, reduced plasma volumes leads to shock and reduced blood flow to kidneys resulting in ARF
how can rhabdomyolysis lead to fatal heart arrhythmias
injured ms leaks potassium
- hyperkalemia may cause fatal disruptions to heart rhythm
since pts w MD are at high risk for rhabdomyolysis, what is a pt education consideration
important to teach them and their families & how we go ab exercising
what are 2 things that are contraindicated for exercise and activity in MD pts
avoid overexertion
avoid eccentric and high-resistance exercise
what are 2 good exercise/activity interventions to recommend in MD
consider cycling/aquatics
encourage standing/walking w/i safe parameters
why are aquatics beneficial in MD
dec body wt in water b/c buoyancy
in early stages of MD (aka amb stage), what exercises are implemented & why
low resistance strength training - less damaged fibers
inspiratory breathing exercises
- reduce loss of VC
conditioning - active exercise via UE/LE ergometry
what is an exercise intervention in MD that should be avoid specifically if later in life
inspiratory breathing exercises
- may be hazardous if not in amb stage
what should PT or other caregivers in child’s life be monitoring for in MD
monitor spin for neuromuscular scoliosis
what are 2 important pt education points
- guarding - fall/injury prevention
- discuss - wheeled mobility as amb becomes more difficult
- what is safe
what are 5 considerations of a wc evaluation
power
standing feature
reclining back
controls
accessibility considerations
what is training will be needed in adolescence and adulthood and how will it evolve as the person w MD gets older
transfer training
- DMD often dep by 12+yo
- will regress from stand pivot to 2 person lift to mechanical lift
what are 4 justifications for passive standing (ie wc that has a standing feature) and which one is #1
1 contracture prevention**
WB and bone mineral density
positioning for function
pressure relief
autosomal recessive vs dominant
autosomal recessive - 1 copy of gene from each parent needed for child to have condition
dominant- only need 1 copy total from either parent
what is the onset of CMD
in utero or w/i 1st yr
what is the first sign of CMD
low ms tone
what is the inheritance of CMD
autosomal recessive or de novo autosomal dominant
describe the dz course of CMD
progressive, may be slow
w/c dependent w/i lifespan
variable course depending on specific type
- developmental achievement varies
- lifespan varies form 1yo to young adulthood
what are the 4 main PT interventions for CMD
- contracture prevention and management
- functional mobility management
- functional strengthening to tolerance
- education
what are 4 interventions to prevent and manage contractures in CMD
orthoses
standers
bivalve casts
TLSO
what is the goal of functional strengthening to tolerance in CMD
to improve head and trunk control
what are 3 important education points for CMD
positioning
facilitation of motor development
chest PT and postural drainage
