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Neurology > NMJ and muscle disorders > Flashcards

NMJ and muscle disorders Flashcards

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1
Q

What is Lambert Eaton Myasthenic syndrome LEMS

A

Autoimmune condition with Ab forming against presynaptic Ca channels

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2
Q

Characteristics of LEMS

A

Proximal muscle weakness
autonomic features
absent deep tendon reflexes

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3
Q

Diagnosis and treatment of LEMS

A

Anti-VGCC Ab - Dx

diaminopyridien - Mx

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4
Q

What is myasthenia gravis MG

A

Autoimmune condition affecting the postsynaptic ACh receptors

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5
Q

Features of MG

A

Thymoma
Ptosis, diplopia, internuclear ophthalmoplegia
Fatiguability - especially after exercise
jaw, facial, phayngeal and respiratory muscles affected
Myasthenia crisis = weakness of respiratory muscles
bulbar palsy
proximal limb muscle weakness

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6
Q

Drugs that can exacerbate MG

A 
Gentamicin
B blockers 
Verapamil 
Phenytoin 
Lithium 
Penicillamine 
chloroquine
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7
Q

Investigations and management of MG

A

Ix - anti-AChR, anti-MUSK, TFT, CT thymus

Mx - Pyridostigmine, thymectomy

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8
Q

Management of myasthenic crisis

A

plasmapharesis and IVIG

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9
Q

Features of myotonic dystrophy

A 
Myotonia = impaired muscle relaxation following use 
Distal muscle weakness 
Ptosis 
Cataracts
Cardiac defects 
Frontal balding
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10
Q

features of LMN disorders

A

weakness
hypotonia
fasciculations

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11
Q

features of UMN disorders

A

hypertonia
spasticity
stiffness

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12
Q

what is a motor unit

A

aMN and all the skeletal muscle fibres it innervates

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13
Q

what is a motor end plate

A

synapse formed between the motor neuron and muscle

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14
Q

describe the presynaptic part of neurotransmission

A

AP moves along the nerve causing depolarisation
voltage gated Ca channels open causing Ca influx
ACh released from vesicles into synaptic cleft

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15
Q

describe the postsynaptic part of neurotransmission

A

ACh diffuses across synaptic cleft
AChR open meaning membrane is permeable to Na and K ions
this causes depolarisation at the motor end plate

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16
Q

which enzyme breaks down ACh at the synaptic cleft

A

acetylcholinesterase

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17
Q

why is curare dangerous

A

occupies same position on AChR but does not open ion channel therefore no muscle contraction –> respiratory muscle paralysis and failure

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18
Q

curare is only toxic when administered PO, true or false

A

FALSE

toxic when IV/IM

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19
Q

list PRE synaptic disorders

A

botulism

LEMS

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20
Q

which microorganism causes botulism and where is it found

A

clostridium botulinum

soil

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21
Q

how does botulinum toxin work molecularly

A

cleaves presynaptic proteins involved in vesicle formation

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22
Q

features of botulism

A

rapid onset weakness with no sensory loss

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23
Q

what is LEMS associated with

A

SCLC

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24
Q

Myasthenia gravis MG is a pre/post synaptic disorder

A

POST synaptic disorder

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25
what is the most common NMJ disorder
MG
26
there is flattening of endplate folds in MG, true or false
true
27
in MG, even with normal amount of ACh, transmission is effective, true or false
false, because there are not enough AChR
28
when do symptoms of MG start
when AChR reduce by 30%
29
which antibodies are associated with MG
ACh antibodies
30
what else is important to look for in patient with MG
thymoma
31
which cranial nerves are affected in bulbar palsy
CN IX, X, XI, XII LMN
32
what is pyridostigmine
acetylcholinesterase inhibitor | allows persistence of ACh in synaptic cleft
33
which antibiotic must be avoided in those with MG and why
gentamicin | causes myasthenic crisis and respiratory failure
34
sarcomeres are present in smooth muscle, true or false
false NO sarcomeres only in skeletal and cardiac muscle
35
describe type 1 muscle fibres
slow oxidative | high resistance to fatigue
36
describe type 2a muscle fibres
fast oxidative
37
describe type 2b muscle fibres
fast glycolytic | low resistance to fatigue
38
what are fasciculations and why do they occur
visible fast fine spontaneous twitch | occur in denervated muscle which becomes hyperexcitable
39
what are fasciculations a sign of
disease of motor neuron
40
what is myotonia
failure of muscle relaxation after use
41
what is myotonia a disorder of
Cl- channel disorder | usually hereditary
42
what is dystonia
uncontrolled muscle cramps and spasms
43
list autoimmune muscle diseases
polymyositis | dermatomyositis
44
what is polymyositis and its treatment
symmetrical progressive proximal weakness developing over weeks-months steroids
45
how high in CK in polymyositis
very high | >1000
46
how does dermatomyositis differ from polymyositis
heliotrope rash | underlying malignancy
47
what is inclusion body myositis
slowly progressive weakness in 60s
48
what is characteristic about inclusion body myositis
thumb sparing
49
inclusion body myositis is responsive to steroids, true or false
FALSE | no steroid response
50
what is the commonest muscular dystrophy
myotonic dystrophy
51
inheritance pattern of myotonic dystrophy and what the genetic defect is
AD | trinucleotide repeat disorder with anticipation
52
infective causes of muscle disease
coxsackie trypansomiasis cistercercosis borrelia
53
toxic causes of muscle disease
drugs - statins, steroids, hydroxychloroquine, amiodarone, OCP, diuretics, IFNa venom
54
what is rhabdomyolysis
skeletal msucle damage resulting in leaking of large quantities of toxic intracellular contents into plasma
55
causes of rhabdomyolysis
crush / trauma seizures statins extreme exercise
56
triad of rhabdomyolysis
myalgia muscle weakness myoglobinuria
57
which scale is used to test muscle power
MRC muscle power grading
58
describe the MRC scale
0 - no movement at all 1 - flicker of movement when attempting to contract muscle 2 - some muscle movement with gravity removed 3 - movement against gravity but not resistance 4 - movement against resistance but not full strength 5 - normal strength
59
What is McArdles disease and what condition are patients at risk of
autosomal recessive condition with myophosphorylase deficiency resulting in impaired glucose release from glycogen in muscles Rhabdomyolysis
60
appearance of Charcot Marie Tooth on histology
onion bulb appearance

Neurology (25 decks)

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