Please enable JavaScript.
Coggle requires JavaScript to display documents.
Neuromuscular Disorders (ii) - Coggle Diagram
Neuromuscular Disorders (ii)
Disorders of NM transmission (MG)
improves with rest or anticholinesterase drugs
transient neonatal myasthenia
transmitted vertically from affected mother to foetus
occurs in 10-30% of neonates born to myasthenic mothers
May occur any time during the first 7-10 d of life
should be monitored closely for signs of resp distress
juvenile myasthenia
ab binds to ACh Rs, reducing no of functional Rs
presentation usually after 10 y/o
ophthalmoplegia, ptosis, loss of facial expression, difficulty chewing, generalised by esp proximal weakness
Dx made after admin of IV edrophonium (should improved sx)
confirmed with detection of AChR abs (in 60-80%) or rarely anti-MUSK abs
Tx = antimuscarinics (neostigmine, pyridostigmine)
in long term immunosuppression used (prednisolone, azathioprine)
plasma exchange used in crises
thymectomy considered if thymoma - 25% remit, 1/2 show improvement
Muscle disorders
Muscular dystophies
Duchenne
most common
1 in 4000 males
XLR, but 1/3 have new mutations
deletion on short arm of X chromo
dystrophin deficiency, excess free radicals, myofibre necrosis
CPK elevated
waddling gait
language delay
mount stairs 1 by 1
run slow, clumsier
average age of dx = 5.5 y/o but often sx much earlier
Gower sign
pseudohypertrophy of calves due to replacement of muscle by fat + fibrous tissue
no longer ambulant by 10-14 y/o
life expectancy = late 20s due to resp failure + CM
1/3 have learning difficulties
scoliosis = common comp
management
exercise to maintain power, mobility + delay scoliosis
prevent contractures by stretching + overnight splints
orthoses + Achilles lengthening to prolong walking
good sitting posture, truncal brace, moulded seat + surgical rod insertion for scoliosis
overnight CPAP or NIPPV for nocturnal hypoxia
self help groups
@ specialist centre
corticosteroids to preserve mobility + prevent scoliosis (MOA unknown)
can identify female carriers
mildly raised CPK
DNA anaylsis
antenatal dx possible
Becker
some functional dystrophin produced
features similar to Duchenne, progresses slowly
average onset = 11 y.o
can't walk by 20s
life expectancy = ranges from late 40s to normal
Congenital
group of mostly AR disorders
present @ birth @ early infancy with weakness, hypotonia, contractures
slowly progressive
Myopathies
congenital
present @ birth/infancy with generalised hypotonia + muscle weakness
static or slowly progressive
CPK normal/mildly elevated
metabolic
glycogen storage disorders
disorders of lipid metabolism
mitochondrial cytopathies (rare)
inflamm
benign acute myositis
assumed to be post viral (often follows URTI)
self limiting
pain, weakness
CPK usually raised
dermatomyositis
probably due to angiopathy
usual onset = 5-10 y/o
typically insidious onset of fever, misery, symm mainly proximal muscle weakness
sometimes pharyngeal muscles involved - affects swallowing
characteristic violaceous heliotrope rash on eyelids + periorbital oedema
rash may affect extensor surfaces of joints
CRP/ESR may be raised
muscle bx: inflamm cell infiltrate + atrophy
physio needed to prevent contractures
tx = corticosteroids + other immunosuppressants (MTX, ciclosporin)
mortality = 5-10%
Bell's palsy
LMN paresis of VII, leads to facial weakness
aetiology unclear, probably viral (a/w HSV)
tx = corticosteroids, no benefit in aciclovir
complete recovery normally, but may take several mo
comp = eye infection due to not being able to close eye fully
prevention = patch or tarsorrhaphy
ddx
compressive lesion in cerebellopontine angle (acoustic neuroma)
if CN VIII paresis too
herpes zoster oticus
painful vesicles on ear
tx = aciclovir
Coarctation of aorta
a/w Bells
look for HTN
if bilat facial weakness consider sarcoid + Lyme disease