88 diseases causing muscle hypotonia (guillain barre, werdnig hoffman, DMD, CP Flashcards
what is GBS
acute postinfectious segmental demylinating polyneuropathy characterized by symmetric and ascending flaccid paralysis.
(more common in adults)
what triggers GBS
URI 1-4wks before onset
fluvaccination is rare
common infectious agents linked to GBS
bac
-Campylobacter jejuni!! most common is campylobacter enteritis
-Mycoplasma pneumoniae
VIRAL
- Cytomegalovirus
- Epstein-Barr virus
PP of GBS
molecular mimicary of pathogenic agens causing cross rxn w/ schwann cell mylein d/2 sim struc
Humoral response( b cells a.bodies) causing segmental inflamm and destruction of the axon’s yelin sheath
reduces the spped & quality of neuronal transmissions
types of GBS 4
Acute inflammatory demyelinating polyneuropathy
-linked to C.jejuni
Chronic inflammatory demyelinating polyneuropathy (CIDP)
-lasts 2 months
Miller-Fisher syndrom
-Affects CRANIAL NERVES
Multifocal motor neuropathy (MMN)
sx of GBS
begins w/ back and limb pain and parasthesias
ASCENDING BILATERAL FLACCID PARALYSIS
socks & gloves
reduced/ absent reflexes
LANDRY paralysis (resp muscles)
affects ANS
-constipation/ voiding
dg of GBS
LP
-increased proteins and wbc in csf
electroneurograph shows lowered nerve conduction velocity
rx of GBS
supportive
-monitor respiratory and carduac func
- IV immunoglobulins in severe forms
- plasmapheresis( filtere plasma from blood and remove toxic subs in this case auto ab’s)
prognosis
schwann cells evetually perform remylination of axons
5% die d/2 respiratory paralysis
what is spinal muscular atrophy
group of autosomal recessive motor neuron diseases caused by apoptosis of lower motor neurons due to deletion of the survival motor gene on chromosome 5
severity depends on the number of defective SMN2 genes available in the genotype
PP oof SMA
involves the bulbar and lower motor neurons
SMN is involved in motor neuron stim and innihibyd apoptosis
lack increases apoptosis of motor neurons and causes poor development of the motor unit causing atrophy of the muscles but with preserved sensory neuron function
eye movement preserved and CN 3,4,6 PRESERVEED
types of SMA
type 1a- severe and hypotonia occurs in utero
type 1b Werdnig-Hoffman disease!!!!!
-severe
-
type 2
- imdt
- 718months
- kiphoscoliosis
type 3
-mild
18months
type 4
- adult (10-30 years)
- normal life
werdnig hoffman sx
onset of 6 months
- symmetrical muscle weakness
- proximal muscles > distal
- pradaoxical breathing d/2 weakness of intercostal muscles
- absent DTR
- weak cry
- FASCICULATIONS
- dysphagia
loss of motor milestone: cant sit up / cant keep head up
life expectancty of 2 years
most common cause of death in SMA
resp failure and pneumonia
dg of SMA
genetic testing
electromyography
muscle biopsy to show atrophy
dx of SMA
polio
other muscluar atrophies (DMD/BECKER)
rx of SMA
definitive
-intrathecal NUSINERSEN( increases the amount of functioning SMN2/ reduces bkdwn)
- resp support
- rehab
progressive muscular dystophies (DUCHENNE/ BECKER)
x linked recessive progressive diseasees d/2 mutaton of the dystrophin gene
dmd; 2-5 years
bmd; 15y/o
PP of dmd
dystrophom seucres cytoskeleton of myocytes to the ECM via actin fillaments
mutaions cause distubance of signal PW, leads to necrosis of myocytes and replacement of connective tissue w. fat tissue leading to PSEUOHYPERTROPHY
sx of DMD
PSUDOHYPERTROPHY of calf
reuced reflexes
gower/s sign
TRENDELENBURG SIGN(waddle gait)
cant walk by 12yo
heart
- dilated cardiomyopathy
- arrythmua]-respiratory inssuf
becker;s
same as DMD but slower /milder as only partial mutation occurs
dg of dmd
Blood tests: ↑↑ creatine kinase
Genetic analysis: detect dystrophin gene mutation
Muscle biopsy
if genetic analysis is -inconclusive
-muscle necrosis
-absent/ reduced dystrophin
dx of DMD
SMA
polymyositis -Muscle biopsy Only performed if genetic analysis is inconclusive -dxw/ increased LDH biopsy shows inflamm infiltrate
rx od=f dmd
no cure
DMD-glucocorticoids
phhysiotherrapy
ventilation support
DMD prog
30 yrs life expectancy d/2 cardiac / pulmonary complications
BMD prog
40-50yr usually cardiogenic cause of death
