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2a - SBCS > Neuro > Flashcards

Neuro Flashcards

1
Q

What 2 antibodies are associated with myasthenia gravis

A
  • Anti-Ach receptors antibodies
  • Anti-Muscle-specific tyroine kinase antibodies (Anti-MuSK)
  • LDL receptor-related protein 4 (Anti-LRP4)
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2
Q

What is myasthenia gravis

A

Chronic autoimmune disorder of the postsynaptic membrane at the neuromuscular junction of skeletal muscle

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3
Q

Describe the gender differences in myasthenia gravis

A
  • Men typically affected over 60
  • Women affected under 40 (mc)
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4
Q

Describe the association between the thymus and myasthenia gravis

A
  • 10% patients have a thymoma
  • 70% have thymic hyperplasia
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5
Q

Explain how Anti-AchR causes the symptoms of myasthenia gravis

A
  • antibodies against Ach receptors competitively inhibit Ach binding = weakness
  • Anti-AchR also activate the complement system within the NMJ which leads to damage to cells at the postsynaptic membrane
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6
Q

Explain why increased muscle activity causes worse symptoms in people with myasthenia gravis

A
  • Receptors are used more during muscle activity so more become blocked up
  • Leads to less effective stimulation of the muscle with increased activity
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7
Q

Give 6 clinical manifestations of myasthenia gravis

A
  • Ptosis and diplopia (early)
  • Muscle strength fatigability - weakness worsens with activity or repetition and improves on rest
  • Dysarthria (speech) and dysphagia (chewing/ swallowing)
  • Facial paresis - transverse smile
  • Proximal limb weakness - e.g. hard to climb stairs
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8
Q

How are tendon reflexes and sensations affected in myasthenia gravis

A

They remain intact/ normal

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9
Q

How is myasthenia gravis investigated

A
  • Serology - Anti AchR and MuSK
  • Repetitive nerve stimulation - shows a decremental muscle response
  • Single fibre electromyography (sensitive)
  • CT chest - thymus enlargement
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10
Q

How is myasthenia gravis managed

A
  • 1st - long acting Acetylcholinesterase inhibitor e.g. pyridostigmine
  • 2nd - Prednisolone
  • 3rd - Immunosuppressant e.g. Azathioprine
  • Thymectomy if thymoma is present
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11
Q

Name 3 drugs that may exacerbate myasthenia gravis

A
  • beta blockers
  • lithium
  • antibiotics: ,macrolides, tetracyclines
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12
Q

What is myasthenic crisis

A

Medical emergency where respiratory muscles weaken and is often provoked by infection or medications

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13
Q

Give 4 ways myasthenic crisis may present

A
  • Increasing shortness of breath
  • Severe limb weakness
  • Quiet breathing
  • Reduced chest expansion
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14
Q

How is myasthenic crisis managed

A
  • Intubation and mechanical ventilation
  • Plasma exchange or IV Ig
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15
Q

What is Lambert-Eaton myasthenic syndrome

A

Rare autoimmune condition affecting both NMJ and autonomic ganglia

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16
Q

Which type of cancer is Lambert-Eaton syndrome associated with

A

Small cell lung cancer

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17
Q

Explain the pathophysiology of Lambert-Eaton syndrome

A
  • Antibodies are produced against voltage gated Ca2+ channels in presynaptic membrane
  • This means there is insufficient Ca to trigger release of Ach into the neuromuscular junction = reduced Ach
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18
Q

Give 6 clinical manifestation of Lambert-Eaton syndrome

A
  • limb-girdle weakness (affects lower limbs first) - waddling gait
  • Strength improved with repeated exertion
  • Dry mouth (Xerostomia)
  • Ptosis and diplopia (late Sx)
  • Dysarthria (difficulty speaking due to weak muscles)
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19
Q

How are tendon reflexes affected in Lambert-Eaton syndrome

A

Reduced/ absent in most patients

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20
Q

Describe 4 investigation that should be conducted for Lambert-Eaton syndrome

A
  • Nerve conduction studies
  • Chest CT - SCLC
  • Ach serology - negative to eliminate myasthenia gravis
  • Presence of voltage gated Ca2+ channel antibodies
21
Q

What would be the expected result of a nerve conduction studies of someone with Lambert-Eaton syndrome

A
  • Initial muscle action potential amplitude is typically low.
  • > 100% increase in amplitude after 10s of exercise in at least one muscle
22
Q

How is Lambert-Eaton syndrome treated

A
  • Treat underlying cause - e.g. treat underlying cancer
  • Amifampridine (3,4-diaminopyridine) +/- pyridostigmine
  • IVIg or plasma exchange
  • Intubation and mechanical ventilation if there is severe respiratory weakness
23
Q

What is Guillain-Barre syndrome

A

Acute inflammatory polyneuropathy involving demyelination of Schwann cells or damage to axons

24
Q

What commonly triggers Guillain-Barre syndrome

A

triggered by an infection (classically Campylobacter jejuni)

25
Q

Explain the pathophysiology of Guillain-Barre syndrome

A

Assumed molecular mimicry:
* cross-reaction of antibodies with gangliosides in the peripheral nervous system
* Ab target Ag on myelin sheath of motor nerve cells and nerve axons
* anti-ganglioside antibody (anti-GM1) seen in 25% of patients

26
Q

Describe the presentation of Guillain-Barre syndrome

A
  • Progressive symmetrical ascending muscle weakness
  • back/ leg pain
  • reduced/ absent reflexes
  • cranial nerve: diplopia, bilateral facial nerve palsy, oropharyngeal weakness
  • Respiratory distress - dyspnoea
  • history of gastroenteritis
27
Q

How is Guillain-Barre syndrome investigated

A
  • Lumbar puncture
  • LFT - raised AST and ALT
  • Spirometry - reduced vital capacity
  • Nerve conduction studies - reduced motor nerve conduction velocity
28
Q

What findings would indicate Guillain-Barre syndrome on lumbar puncture

A
  • isolated Raised protein
  • Normal white blood cells
29
Q

How is Guillain-Barre syndrome treated

A
  • IVIg for 5 days + plasma exchange
  • DVT prophylaxis - short acting HTN agents e.g. labetalol
  • resp failure: mechanical ventilation or intubation
30
Q

When is IVIg contraindicated in the treatment of Guillain-Barre syndrome

A

IgA deficiency and renal failure

31
Q

What is multiple sclerosis

A

chronic cell-mediated autoimmune disorder characterised by demyelination in the central nervous system

32
Q

What age is multiple sclerosis most commonly diagnosed

A

between age 20 - 40

33
Q

Give 4 RFs of multiple sclerosis

A
  • Female (3x mc)
  • Family history
  • Smoking
  • EBV
34
Q

Explain the pathophysiology of multiple sclerosis

A
  • myelin is produced by oligodendrocytes in the CNS
  • In MS, demyelination happen when T cells infiltrate the BBB and release cytokines which directly damage oligodendrocytes
35
Q

What type of hypersensitivity reaction is multiple sclerosis

A

Type 4

36
Q

Describe the 3 subtypes of multiple sclerosis

A
  • Relapsing-remitting - episodic flares with periods of remission
  • Primary progressive - progressive deterioration from onset, mc in older people
  • Secondary progressive - initially relapsing-remitting but develops to primary progressive
37
Q

What is the most common subtype of multiple sclerosis

A

Relapsing-remitting (85%)

38
Q

Give 6 clinical characteristics of multiple sclerosis

A
  • Optic neuritis
  • significant lethargy
  • paraesthesia and numbness
  • Trigeminal neuralgia
  • Lhermitte’s sign - shooting sensation and paraesthesia in limbs on neck flexion
  • Uhthoff’s phenomenon - worse Sx after a rise in temp e.g. hot bath
  • spastic weakness: most commonly seen in the legs
  • incontinence
39
Q

State the name and explain the diagnostic criteria for multiple sclerosis

A

McDonald criteria - Sx demonstrating dissemination in space and time on MRI

2 or more relapses and either:
* Objective clinical evidence of 2 or more lesionsor
* Objective clinical evidence of one lesionwitha reasonable history of a previous relapse

40
Q

Give 3 ways that multiple sclerosis is investigated

A
  • MRI brain and spine with contrast
  • Lumbar puncture
  • Visual evoked potentials
41
Q

What may be seen on an MRI brain/spine of someone with multiple sclerosis

A
  • Periventricular demyelinating plaques: Dawson’s fingers - hyperintense lesions perpendicular to the corpus callosum
  • Old lesion will not enhance as well with contrast compared to newer lesions
  • evidence of lesions disseminated in time and space
42
Q

What findings would indicate multiple sclerosis on CSF analysis

A
  • Glucose and protein should be normal
  • Oligoclonal bands and elevated CSF IgG
43
Q

What may evoked potentials show in a patient with multiple sclerosis

A

Asymmetrical prolongation of conduction
Normal amplitude

44
Q

How is an acute relapse of multiple sclerosis managed

A

1st line - high dose Oral/ IV methylprednisolone for 5 days
Consider - Plasma exchange

45
Q

What are the drug options for reducing the risk of relapse in multiple sclerosis

A
  • IV Natalizumab (mAb)
  • IV ocrelizumab (mAb)
  • Oral Fingolimod (S1P receptor modulator)
  • SC Glatiramer acetate - immunomodulator
  • IM/ SC interferon beta
46
Q

How is fatigue managed in multiple sclerosis

A
  • amantadine
  • mindfulness training and CBT
47
Q

How is spasticity managed in multiple sclerosis

A
  • 1st - baclofen
  • 2nd - gabapentin
  • physio
48
Q

How is bladder dysfunction managed in multiple sclerosis

A
  • ultrasound first to assess bladder emptying
  • if significant residual volume → intermittent self-catheterisation
  • if no significant residual volume → anticholinergics (oxybutynin) may improve urinary frequency
49
Q

Give 4 complications of multiple sclerosis

A
  • UTIs
  • Depression
  • Visual impairments
  • Osteopenia and osteoporosis

2a - SBCS (9 decks)

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