Chapter 131 - Pediatric Neuromuscular Disorders Flashcards
botox mechanism of action
irreversibly binding to synaptic proteins at the NMJ to block pre-synaptic release of acetylcholine
is Botox FDA approved??
only for adults in upper extremity spasticity
used off label in kids with CP
hip flexor contractures can lead to what spine manifestation
hyperlordosis -> spondylolisthesis
cp patients < 5th percentile for weight carry what risks?
post operative spinal fusion complicaitons
- hardware failure
- infection
- pulm complications
- GI complications
curves exceeding 90 degrees require what?
anterior release with posterior fusion (one or two stage procedure)
outcomes of surgically treated scoli in cp
increase in quality of life - sitting balance, cosmesis, care giver satisfaction, lifespan
NO functional gains/benefits
how does hip subluxation differ from DDH
POSTEROSUPERIOR dislocation
2/2 spasticity of adductor, iliopsoas tendons
(obturator n predomintely)
will develop in 50% of quadriplegics (less common in ambulatory kids)
how to surgically treat CP hip dislocation?
age <8, <60%subluxation: addutor, gracilis tenotomy (add IP tenotomy if hip flexion contracture >20deg)
age <8, >60% subluxation: valgus derotation osteotomy
Age >8, >40% subluxation get VDRO and/or pelvic osteotomy (dega or albee)
Closed triradiates - chiari osteotomy
how to treat scissoring in CP
- adductor contracture
- proximal adductor release
DO NOT do obturator neurotomy
grouched gait is a result of what?
spastic or contracted hamstrings
less commonly from too much dorsiflexion in the ankle of ankle equinus
risk factors for myelomeningocele
previously affected pregnancy
low folic acid intake
pre-gestational maternal diabetes
in utero exposure to valproic acid or carbamazepine
what is the distal most level that can be affected in myelomeningocele and still allow community ambulation
L3
Need L4 for quadriceps control
what to do for kids with dislocated hip and myelomeningocele
nothing
leave a dislocated hip alone
high risk of recurrence
child or SCI patient with a red hot swollen leg has what until proven otherwise?
fracture
x lined recessive gene defect is where?
patients mother’s paternal side - usually new mutations in spermatogenesis
duchenne muscular dystrophy
X Linked recessive
skeletal and cardiac muscle
1:3500 males
Xp21.2 (point deletion - nonsense mutation) - DYSTROPHIN - stabilizes the muscle cell membrane is ABSENT
Presentation of DMD
between age 3-6, toe walking, flatfootedness, cant run or climb stairs, calf pseudohypertrophy, gowers sign (use UE to get off floor)
affects PROXIMAL muscles > distal muscles
Elevated CPK
medical treatment for DMD
corticosteroid - emflaza/deflazacort
decreased the need for scoliosis fusion (from 92-> 20%), slows deterioration of forced vital capacity
side effects are all those associated with long term corticosteroids
effects of night time ventilation for DMD patients
substantially prolongs survival
dont brace DMD scoli
ineffective and not recommended
early fusion for curves >20 is recommended to preserve forced vital capacity
!!! DMD patients are at risk for malignant hyperthermia - avoid inhalational anesthetics and succinylcholine
Spinal Muscular Atrophy genetics
Autosomal recessive
1:10000 children
phenotype for SMA
progressive weakness that starts proximally and moves distally thru the body
SMAI: onset at birth, severe spinal manifestations, death by age II
SMA II: onset 6-18 months, weakness worse in LE, hip dislocation common, life expectancy 15+ yr
SMA III: onset >18mo, stand independently at first, but wheelchair bound as adults, more proximal weakness, normal life expectancy
SMA IV: onset in adulthood, moderate proximal mm weakness
genetic defect in SMA
survival motor neuron chromosome 5 mutation
result in progressive alpha motor neuron loss in the anterior horn of the spinal cord with associated progressive weakness
Charcot marie tooth most common inheritance pattern and most common genetic defect
autosomal dominant most common
PMP-22 - peripheral myelin protein 22 on chromosome 17 most common mutation
x-lined connexin 32 mutation also common
CMT phenotype
CMT is a very common cause of peditric cavus foot diagnosed before age 10
cavus foot, claw toes, foot drop
foot affected first, then hands, and tongue
increased incidence of scoli and hip dysplasia
DISTAL muscle weakness
Hip pathology in CMT
hip dysplasia ALWAYS requires treatment in CMT
- acetabular reconstruction favored over VDRO
pathophysiology behind the cavus foot in CMT
weak tib ant causes equinus.
weak peroneus brevis causes heel varus
strong peroneus longus causes plantar flexion of the first ray, planus
contracted platar fascia contributes to pes planus
normal fhl.fdl cause clawing
flexible cavovarus in CMT
plantar fascia release
peroneus longus to brevis rtansfer
ehl transfer to the first MT head
proximal first MT closing wedge osteotomy
tib ant transfer
fixed cavovarus CMT
calcaneal osteotomy
friedrich’s ataxia
most common form of the uncommon spinocerebral degenerative diseases
three nucleotide repeat accumulation GAA
FRATAXIN gene on chromosome 9q13
results in loss of the protein frataxin -> normally responsible for cellular IRON hemostasis
glute max involvement first, severe scoli and cavovarus foot, ataxia, areflexia
assoc with hypertrophic cardiomyopathy, diabetes, hearing or vision loss
Rett syndrome
X linked dominant - LETHAL in affected male fetus’
most often denovo mutation
impaired DNA methylation
