Neuromuscular Disorders Flashcards
what structures may be affected in neuromuscular disorders
- anterior horn cell
- peripheral nerve
- muscle
what is common to all neuromuscular disorders
muscle weakness leading to loss of function and potential physical deformity
T or F: neuromuscular disorders may be hereditary or acquired
T
muscular dystrophies are a group of _______
myopathies
in myopathies, the pathology is in the…
muscle tissue
dystrophinopathies
- deficient dystrophin
- duchenne’s and becker’s muscular dystrophy
sarcoglycanopathies
- deficient sarcoglycans
- limb muscle dystrophies
laminin deficiency
congenital muscular dystrophy
in neuropathies the pathology is in the… (2)
- anterior horn cell (spinal muscular atrophy)
- peripheral nerve (charcot-marie-tooth)
are muscle dystrophies genetic? are they progressive?
yes and yes
how are muscular dystrophies classified
clinical presentation and mode of inheritance/gene deficiency
what is the most prevalent muscular dystrophy
duchenne’s (AKA: pseudohypertrophic)
how is DMD inherited
x-linked recessive
T or F: females with DMD mutation are typically asymptomatic
T
what makes beckers MD different from DMD
it progresses at a much slower rate because some dystrophin is produced
*symptoms appear at 5-15 (maybe even 20-30s)
life expectancy from BMD? how long can they maintain independent ambulation
30-40 y/o
15 y/o
pathophysiology of DMD/BMD
lack of dystrophin > sarcolemmal instability > membrane microtears > calcium channels leak > increased intracellular calcium > muscle cell necrosis
what can worsen membrane microtears in DMD/BMD
muscle contraction
how to diagnoses DMD/BMD (4)
- clinical signs
- high serum creatine kinase
- EMG
- muscle biopsy
what will you see on a muscle biopsy of someone with muscular dystrophy
- degenerating of regenerating fibers
- lack of dystrophin
when do MSK symptoms of DMD start to appear
2-5 y/o
*earliest signs of DMD
what are some MSK symptoms of DMD
- falling/clumsy
- toe walking
- difficulty with stairs
- reluctance to walk/run
- difficulty getting off floor
- pseudohypertrophy of gastrocs, infraspinatus, and delts
gower’s sign
when asked to get up from sitting on floor, child will mvoe hands on legs as though crawling up to the thighs and then assume a standing position
T or F: DMD is often misdiagnosed intially
T
does weakness from DMD start in proximal or distal muscles
- proximal
- esp neck flexors, hip abd/ext/flex and knee ext
T or F: weakness in DMD is steadily progressive
T: but function/activity may not always decline from one exam to the next
what may you notice about gait and posture in a child with DMD
- increased lumbar lordosis
- UE mid-guard
- increased BOS, decreased step length
- waddling gait
typical contractures in boys with DMD
- hip flexors
- ITBs
- gastrocs
*then with w/c use knee and elbow flexors
what causes scoliosis in DMD
starts as neuromusclar due to weaker back muscles and more time sitting but then becomes structural over time
most boys with MDM lose all walking skills by ______ years old
12-13
should you request a manual or power chair for a child with MDM and why
power because a manual requires repeated contractions
what is typically the cause of death in DMD
- respiratory and cardiac issues
- respiratory musculature atrophies
T or F: muscles of the GI tract are affected in DMD
T
what cardiac complications do children with DMD often experience
- cardiomyopathy
- arrhythmias
- CHF
is cardiac or skeletal muscle affected first in DMD
skeletal
T or F: there is a high rate of intellectual impairments, reading difficulties, and attention/emotional differences in boys with DMD
T
T or F: cognitive impairments in DMD are progressive
F: also not related to severity of disease
life expectancy for DMD
25 years
30 years with excellent medical care
T or F: there is a treatment for DMD
F: there are many clinical trials
(gene therapies)
what are some experimental treatments for DMD
- gene replacement
- exon skipping
- myostatin inhibitors
- stem cells
what medication is often used in DMD
glucocorticoid corticosteroids (prednisone and deflazacort)
T or F: MMT should be a routine part of the PT exam/eval of a child with DMD. why or why not
T: after 1 year of serial MMT you can estimate the rate of progression to help predict when bracing and wheeled mobility will be needed
T or F: early loss of ambulation is usually due to muscle weakness in DMD
F: usually due to loss of ROM/contracture
*so measure ROM well and often
what kind of exercise should you avoid in boys with MDM> what kind should you use instead?
- avoid max resistance and eccentric exercise
- submaximal endurance training
*important to avoid overuse
do limb girdle muscular dystrophies affect proximal or distal musculature
proximal
- presentation is very variable and pathology is very heterogenous
how is myotonic dystrophy inherited
autosomal dominant
chromosome 19
what are symptoms of myotonic dystrophy and when do they typically present
- myotonia (delayed muscle relaxation)
- weakness
- present in adolescence
with myotonic dystrophy, does weakness start proximally or distally
distal
ex: foot drop, difficulty opening jars
are smooth and cardiac muscle involved in myotonic dystrophy
yes… death frequently due to cardiac/respiratory issues
the most severe form of myotonic dystrophy is noted at_______
birth
charcot-marie-tooth disease (CMT)
hereditary motor and sensory neuropathy
- primarily in distal musculature of hands/feet
is charcot-marie-tooth progressive
yes
where is the defect most often with charcot-amrie-tooth
myelin
- but sometimes it is in the axon itself
