Nerve and muscle disease Flashcards

1
Q

What are the three types of muscle?

A

Skeletal, smooth, cardiac

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Describe skeletal muscle

A

Highly organised

There is an endomysium, perimysium and epimysium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is a fascicle encapsulated by?

A

Perimysium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are a large group of fascicles encased in?

A

Epimysium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the smallest contractile unit surrounded by?

A

Endomysium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Describe smooth muscle

A
Cells not striated
Single central network
Significant connective tissue around them
No sarcomeres
Actin:Myosin ratio 10:1
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are the three types of smooth muscle fibres?

A

Type I
Type IIa
Type IIb

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Describe type 1 fibres

A

Slow oxidative- dense capillary network, myoglobin, resist fatigue

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Describe type IIa fibres?

A

Fast oxidative- aerobic metabolism

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Describe type IIb fibres?

A

Fast glycolytic, easily fatigued

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is myotonia?

A

Failure of muscle relaxation after use

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are fasciculations?

A

Visible, fast, fine, spontaneous twitch

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Fasciculations only appear if muscle has pathology TRUE/FALSE

A

May occur in healthy muscle-triggers include stress, caffeine and fatigue
Usually a sign of disease in motor neurone

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What myopathy can statins cause?

A

Autoimmune myositis (always check CK)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What 5 drugs can cause myopathies?

A
Statins
Hydroxycloroquine
Amiodarone
Diuretics
A-interferon
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the MRC muscle power grading?

A

0-No movement at all
1-Flicker of movement when attempting to contract muscle
2-Some muscle movement if gravity removed but none against gravity
3- Movement against gravity but not against resistance
4- Movement against resistance but not full strength
5-Normal strength

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Name a postsynaptic disorder

A

Myasthenia gravis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Name 2 presynaptic disorder

A

Botulism-Clostridium botulinum

Lambert Eaton Myasthenic Syndrome (LEMS)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What are the synapses formed between motor neurones and muscle called?

A

Motor end plates

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Where do the cell bodies that innervate the motor neurones that innervate the skeletal muscle fibres arise?

A

Ventral horn of the spinal cord

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

TRUE/FALSE

A single motor neuron may control many muscles but each muscle cell responds only to one motor neuron

A

TRUE

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What is curare?

A

Muscle relaxant used in anaesthetics that competes with acetylcholine and blocks transmission of information

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is McArdle’s disease?

A

AR, usually presents in 1st decade of life
caused by myophosphorylase deficiency
Muscle pain soon after starting exercise
Second wind phenomenon

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Why should patients with McArdles disease stop if they get severe pain when exercising?

A

As it may increase risk of rhabdomyolysis with myoglobinuria and subsequent AKI

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Name the chronic autoimmune disease affecting post-synaptic nicotinic acetylcholine receptors at NMJ

A

Myasthenia gravis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What is the most common disorder of the NMJ?

A

Myasthenia gravis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What is the typical Myasthenia gravis patient?

A

F>M (ratio 3:2)
Females in 3rd decade
Males in 6/7th decade

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

When do the symptoms of myasthenia gravis start?

A

When the number of Ach receptors decreases to 30% of normal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

Clinical features of myasthenia gravis

A

Muscle fatiguability/weakness
Occular features commonly appear first
Proximal muscle weakness more marked than distal muscles
Jaw, facial muscles, speech and/or swallow and resp muscles are also affected
weakness on neck flexion

30
Q

Name two complications of myasthenia gravis

A

Myasthenia crisis

Cholinergic crisis

31
Q

What is myasthenia crisis?

A

Weakness of muscles of respiration cause ventilator failure

32
Q

How do you monitor for myasthenia crisis?

A

Measure vital capacity and tidal volume

If vital capacity falls below 15mL/kg then urgent elective tracheal intubation and ventilation considered

33
Q

What is the treatment for myasthenia crisis?

A

Plasmapheresis
IV immunoglobulins
Systemic steroids

34
Q

What are the symptoms of cholinergic crisis?

A

Sweating
Hypersalivation
Bronchial hyper secretions and miosis

35
Q

Name 4 common associations with myasthenia gravis

A

Thymic hyperplasia
Thymoma
Hyperthyroidism
SLE

36
Q

What is the drug to look out for which can exacerbate myasthenia?

A

Gentamicin

37
Q

What testing is done for myasthenia gravis?

A

Anti-AchR

If this is negative can check for anti-MuSK

38
Q

what are the three investigations for those you suspect to have myasthenia gravis?

A
Antibody testing (anti-AchR and anti-MuSK)
Repetitive nerve stimulation tests
Thyroid function test and CT thymus
39
Q

What is symptomatic control of acetylcholinesterase inhibition with?

A

Pyridostigmine

40
Q

What immunosuppressive agents are used to improve myasthenic weakness and establish remission

A

Corticosteroids

Azathioprine

41
Q

In myasthenia gravis what is morbidity due to?

A

Resp failure and aspiration pneumonia

42
Q

Describe muscular dystrophy

A

Inherited, non inflammatory, progressive, no central or peripheral abnormality

43
Q

What is the commonest muscular dystrophy in adults?

A

Myotonic dystrophy

44
Q

What is myotonic dystrophy and how is it inherited?

A

Multisystem progressive disease

AD: tri-nucleoide repeat on Ch 19 (with anticipation)

45
Q

What are the clinical features of myotonic dystrophy?

A
Sternocleidomastoid & distal limb muscle affected first 
Facial weakness 
ptosis, ophthalmoplegia
Christmas tree like cataracts
Hollowing of temples
Early frontal balding
46
Q

What is Lambert-Eaton Myasthenic syndrome (LEMS)?

A

NMJ disorder caused by impaired release of acetylcholine by pre-synaptic terminal due to autoimmune antibodies

47
Q

What has LEMS got a strong association with?

A

Underlying small cell carcinoma

48
Q

What are the clinical features of LEMS?

A
Insidious onset of weakness of proximal muscles (lower extremity mainly affected)
Autonomic features (constipation, postural hypotension, impotence and dry mouth)
Deep tendon reflexes diminished/abscent
49
Q

What is diagnosis of LEMS established by?

A

Presence of anti-VGCC antibodies
Characteristic electrophysiological findings using a 20-50Hz repetitive stimulation
CT scan (to rule out malignancy)

50
Q

What is the treatment for LEMS?

A

3,4-diaminopyridine (amifampridine)

51
Q

What is Charcot-Marie-Tooth disease?

A

A group of hereditary neuropathies
Can be inherited or AD (most common), AR or X-linked
Onset in first 2 decades with motor symptoms In lower limbs
Sensory loss follows same pattern as muscle weakness
Inverted champagne bottle appearance

52
Q

What does Charcot Marie Tooth disease look like histopathologically?

A

Schwann cells proliferate and form concentric arrays of demyelination around the demyelinated axon - onion bulb appearance

53
Q

What is Guillian Barre syndrome?

A

Acute neuromuscular weakness causing demyelination and axonal injury

54
Q

With GBS what infections do most patients have a preceding history of?

A

Campylobacter

55
Q

How does GBS present?

A

Symmetrical, progressive ascending sensorimotor paralysis

Usually stops progressing 4wks from its onset

56
Q

How is GBS diagnosed?

A

Usually clinical
However
LP (show high CSF protein) and nerve conduction studies (suggestive of patchy proximal and distal demyelination ) sometimes helpful

57
Q

What is the management of GBS?

A

Plasma exchange or IV immunoglobulins

58
Q

What is chronic inflammatory demyelinating polyradiculoneuropathy (CIPD)

A

Acquired demyelinating peripheral nervous system disease characterised by progressive or relapsing proximal and distal weakness with hyporeflexia/areflexia and a distal sensory loss (paraesthesia and numbness)

59
Q

How is CIDP diagnosed?

A

CliniCAL

Supported by electrophysial nerve conduction studies & CSF analysis (high protein)

60
Q

What is the treatment for CIPD?

A

Oral steroids or IV immunoglobulins

61
Q

What is Spinal muscular atrophy?

A

AR neuromuscular disorder
Congenital degeneration of anterior horns of spinal cord (LMN lesions) which leads to progressive muscular wasting often leading to early death

62
Q

What does the severe form of spinal muscular atrophy manifest itself as in early life?

A

Floppy baby syndrome

63
Q

What is poliomyelitis?

A

Symmetrical progressive proximal weakness developing over weeks to months

64
Q

What is poliomyelitis caused by?

A

Poliovirus (faecal-oral transmission

The infection causes destruction of cells in the anterior horn of spinal cord (LMN death)

65
Q

What is dermatomyositis similar to?

A

Clinically similar to poliomyelitis but ass with skin lesions, “heliotrope” rash on face
up to 50% have underlying malignancy

66
Q

How does inclusion body myositis present?

A

Typically slowly progressive weakness in 6th decade of life with characteristic thumb sparing

67
Q

What is rhabdomyolysis?

A

Dissolution of muscle

Damage to skeletal muscle causes leakage go large quantities of toxic intracellular contents into plasma

68
Q

How does rhabdomyolitis present?

A

Triad
Myalgia
Muscle weakness
Myoglobinuria

69
Q

What can be complications of Rhabdomyolysis?

A

Acute renal failure

DIC

70
Q

What is botulism- clostridium botulinum from?

A

Organism present in soil
Food and wounds can become infected
ALSO IV drug users-black tar heroin

71
Q

How does botulism-clostridium botulinum present?

A

Rapid onset weakness without sensory loss

72
Q

How does botulism-clostridium botulinum work its magic?

A

It cleaves presynaptic proteins involved in vesicle formation and blocks vesicle docking with the presynaptic membrane