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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
  • phenytoin
  • 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
  • immunosuppression
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
Explain the pathophysiology of Guillain-Barre syndrome
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
Describe the presentation of Guillain-Barre syndrome
* 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
How is Guillain-Barre syndrome investigated
* Lumbar puncture * LFT - raised AST and ALT * Spirometry - reduced vital capacity * Nerve conduction studies - reduced motor nerve conduction velocity
28
What findings would indicate Guillain-Barre syndrome on lumbar puncture
* isolated Raised protein * Normal white blood cells
29
How is Guillain-Barre syndrome treated
* plasma exchange or IVIg for 5 days * resp failure: mechanical ventilation or intubation
30
When is IVIg contraindicated in the treatment of Guillain-Barre syndrome
IgA deficiency and renal failure
31
What is multiple sclerosis
chronic cell-mediated autoimmune disorder characterised by demyelination in the central nervous system
32
What age is multiple sclerosis most commonly diagnosed
between age 20 - 40
33
Give 4 RFs of multiple sclerosis
* Female (3x mc) * Family history * Smoking * EBV
34
Explain the pathophysiology of multiple sclerosis
* 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
What type of hypersensitivity reaction is multiple sclerosis
Type 4
36
Describe the 3 subtypes of multiple sclerosis
* 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
What is the most common subtype of multiple sclerosis
Relapsing-remitting (85%)
38
Give 6 clinical characteristics of multiple sclerosis
* 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
State the name and explain the diagnostic criteria for multiple sclerosis
McDonald criteria - Sx demonstrating dissemination in space and time on MRI 2 or more relapses and either: * Objective clinical evidence of 2 or more lesions * Objective clinical evidence of one lesion,  with reasonable history of a previous relapse
40
Give 3 ways that multiple sclerosis is investigated
* MRI brain and spine with contrast * Lumbar puncture * Visual evoked potentials
41
What may be seen on an MRI brain/spine of someone with multiple sclerosis
* 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
What findings would indicate multiple sclerosis on CSF analysis
* Glucose and protein should be normal * Oligoclonal bands and elevated CSF IgG
43
What may evoked potentials show in a patient with multiple sclerosis
Asymmetrical prolongation of conduction Normal amplitude
44
How is an acute relapse of multiple sclerosis managed
1st line - high dose Oral/ IV methylprednisolone for 5 days Consider - Plasma exchange
45
What are the drug options for reducing the risk of relapse in multiple sclerosis
* IV Natalizumab (mAb) * IV ocrelizumab (mAb) * Oral Fingolimod (S1P receptor modulator) * SC Glatiramer acetate - immunomodulator * IM/ SC interferon beta
46
How is fatigue managed in multiple sclerosis
* amantadine * mindfulness training and CBT
47
How is spasticity managed in multiple sclerosis
* 1st - baclofen * 2nd - gabapentin * physio
48
How is bladder dysfunction managed in multiple sclerosis
* 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
Give 4 complications of multiple sclerosis
* UTIs * Depression * Visual impairments * Osteopenia and osteoporosis

2a - SBCS (9 decks)

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