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Roomies Collab Deck 2: Endocrinology and NeuroPsych > Neuromuscular Disorders > Flashcards

Neuromuscular Disorders Flashcards

1
Q

_______________ are used as first-line treatment in ocular myasthenia gravis and as an adjunct to immunosuppressant therapy for generalised myasthenia gravis.

A

AChE inhibitors

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2
Q

_______________ are used as first-line treatment in ocular MG

A

AChE inhibitors

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3
Q

Can AChE inhibitors be used alone in the treatment of generalized MG?

A

No; usually used as an adjunct in combination wit corticosteroids

(Azathioprine also frequently used to reduce the dose of corticosteroid)

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4
Q

______________ or _________________ may induce temporary remission in severe relapses in MG, particularly where bulbar or respiratory function is compromised or before thymectomy.

A

Plasmapheresis

infusion of intravenous immunoglobulin [unlicensed indication]

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5
Q

What is the pathophysiology of Myasthenia Gravis?

A

Antibodies that block or destroy ACh, resulting in muscle weakness

Often related to deranged thymus function (investigate for thymoma)

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6
Q

What is the primary symptom of MG?

A

Muscle weakness

*may affect vision, speech, swallowing in early disease, and ambulation/head and arm movements/breathing in later disease

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7
Q

In the majority of people diagnosed with MG, what are the first signs/symptoms?

A

Involvement of the eye:

  • drooping of one or both eyelids (ptosis)
  • diplopia (vertical or horizontal) which resolves when one eye is closed

In 15% of people, the first symptoms involve the face and throat muscles causing:

  • impaired speech
  • dysphagia
  • difficulty chewing
  • change of facial expression
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8
Q

In a minority of patients with MG, the primary symptoms involve muscles of the…?

A

In 15% of people, the first symptoms involve the face and throat muscles causing:

  • impaired speech
  • dysphagia
  • difficulty chewing
  • change of facial expression
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9
Q

What is myasthenia crisis?

A

A life-threatening condition that occurs in patients with MG when the muscles of breathing are compromised

Emergency treatment and mechanical ventilation are required; patients are also offered urgent plasmapheresis and IVIG

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10
Q

___________ (surgery) is offered to patients with MG.

A

Thymectomy

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11
Q

AChE inhibitors enhance neuromuscular transmission in voluntary ______ (and/or) involuntary muscles in myasthenia gravis.

A

AND

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12
Q

Excessive dosage of AChE inhibiting drugs can impair ___________ and precipitate ____________ by causing a depolarising block

A

neuromuscular transmission

cholinergic crises

  • This may be difficult to distinguish from a worsening myasthenic state.
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13
Q

The depolarizing block in by cholinergic toxicity causes a flaccid/spastic paralysis?

A

Flaccid (thus, can mimic muscle weakness in a worsening myasthenic state)

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14
Q

___________ side-effects of anticholinesterase inhibitors include increased sweating, increased salivary and gastric secretions, increased gastro-intestinal and uterine motility, and bradycardia.

A

Muscarinic

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15
Q

These parasympathomimetic effects of AChE inhibitors are antagonised by ______________ (drug)

A

atropine sulfate

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16
Q

Neostigmine produces a therapeutic effect for up to__________. Its pronounced __________ action is a disadvantage, and simultaneous administration of an ____________ drug such as atropine sulfate or propantheline bromide may be required to prevent colic, excessive salivation, or diarrhoea

A

4 hours

muscarinic

antimuscarinic

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17
Q

In severe disease, neostigmine can be given every __________. The maximum that most patients can tolerate is _________ daily

A

2 hours

180 mg

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18
Q

Pyridostigmine bromide is ________ (more/less) powerful and __________ (faster/slower) in action than neostigmine but it has a ________ (shorter/longer) duration of action

A

Less

Slower

Longer

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19
Q

_______________ is preferable to neostigmine because of its smoother action and the need for less frequent dosage

A

Pyridostigmine

*It is particularly preferred in patients whose muscles are weak on waking

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20
Q

Compared to neostigmine, the GI side effects of pyridostigmine are _________ (greater/milder)

A

Milder, but an antimuscarinic may still be required

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21
Q

____________ are established as treatment for myasthenia gravis

A

Corticosteroids

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22
Q

Corticosteroid treatment for MG is usually initiated under in-patient supervision and all patients should receive _____________ prophylaxis.

A

osteoporosis

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23
Q

In generalised myasthenia gravis _____________ (corticosteroid) is given.

A

prednisolone

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24
Q

In generalised myasthenia gravis prednisolone is given. About 10% of patients experience a transient but very serious worsening of symptoms in the first __________, especially if the corticosteroid is started at a high dose.

A

2-3 weeks

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25
Q

Compared to general MG, __________ (larger/smaller) doses of corticosteroid are usually required in ocular myasthenia

A

Smaller

26
Q

Once clinical remission has occurred in MG (usually after _________), the dose of prednisolone should be reduced slowly to the minimum effective dose.

A

2–6 months

27
Q

In generalised myasthenia gravis _________ is usually started at the same time as the corticosteroid and it allows a lower maintenance dose of the corticosteroid to be used.

A

azathioprine

28
Q

Which drugs can be used in patients with MG who are unresponsive or intolerant to other treatments?

A
  • cyclosporin
  • MTX
  • mycophenolate mofetil

(All unlicensed)

29
Q

What is Lambert-Eaton myasthenic syndrome?

A

Autoantibodies to presynaptic voltage-gated Ca channels in the membrane of the motor nerve terminal (vs ACh receptors on the postsynaptic nerve in MG); blockage impairs ACh release, leading to weakness of striated skeletal muscle

This weakness can characteristically be overcome by repeated movement (unlike in MG, where weakness is exacerbated by repeated movement)

LEMS may be associated with a paraneoplastic syndrome OR a primary autoimmune disorder

30
Q

______________ is licensed for the symptomatic treatment of Lambert-Eaton myasthenic syndrome (LEMS)

A

Amifampridine

31
Q

_____________ is licensed for the improvement of walking in patients with Multiple sclerosis who have a walking disability.

A

Fampridine

32
Q

What is the role of skeletal muscle relaxants in neuromuscular disease?

A

Relief of chronic muscle spasm or spasticity, especially associated with MS or other neurological damage (remember, spasticity is associated with UMN damage/CNS dysfunction, not LMN damage)

33
Q

Are skeletal muscle relaxants used for spasm associated with minor injuries?

A

No

34
Q

Baclofen, diazepam, and tizanidine are skeletal muscle relaxants that act principally on the _________ (central/peripheral) nervous system, whereas dantrolene has a __________ (central/peripheral) site of action

A

Central

Peripheral

35
Q

In the treatment of muscular spasm and spasticity, where in the nervous system do cannabis extracts act?

A

Centrally and peripherally

36
Q

Skeletal muscle relaxants differ in action from the muscle relaxants used in anaesthesia, which block transmission at the ______________

A

neuromuscular junction

37
Q

What factors may aggravate spasticity in neuromuscular disorders? (2)

A
  1. Pressure sores

2. Infection

38
Q

What is the major disadvantage of skeletal muscle relaxants in the treatment of neuromuscular disorders?

A

Reduction in muscle tone can cause a loss of splinting action of the spastic leg and trunk muscles and sometimes lead to an increase in disability

39
Q

What are the skeletal muscle relaxants and how do they differ from muscle relaxants used in anesthesia?

A

Skeletal muscle relaxants: baclofen, dantrolene, diazepam, tizanidine, cannabis extract

Unlike muscle relaxants used in anesthesia which act at the NMJ, these drugs primarily act centrally (with the exception of dantrolene which acts peripherally, and cannabis, which acts BOTH centrally and peripherally)

40
Q

What are the neuromuscular disorders? (8)

A
  1. ALS (most common motor neuron disease)
  2. Charcot-Marie-Tooth
  3. MS
  4. Muscular dystrophy
  5. Myasthenia gravis (most common neuromuscular disorder)
  6. Myositis (including poly- and dermato-)
  7. Peripheral neuropathy
  8. Spinal muscular atrophy
41
Q

Baclofen is a _________ agonist that causes skeletal muscle relaxation by inhibiting transmission at _______ level and also depresses the __________

A

GABA

spinal

central nervous system

42
Q

The dose of baclofen should be increased slowly to avoid the major side-effects of __________ and ____________

A

Sedation

Muscular hypotonia

(Other side effects are uncommon)

43
Q

Dantrolene sodium acts directly on __________ and produces fewer ____________ adverse effects making it a drug of choice. The dose should be increased slowly

A

skeletal muscle

central

44
Q

What are the disadvantages to using diazepam in the treatment of neuromuscular disorders? (2)

A
  1. Sedation

2. Extensor hypotonus

45
Q

Tizanidine is an ___________ agonist indicated for spasticity associated with Multiple sclerosis or spinal cord injury

A

alpha2-adrenoceptor

46
Q

_____________ is an alpha2-adrenoceptor agonist indicated for spasticity associated with Multiple sclerosis or spinal cord injury

A

Tizanidine

47
Q

Tizanidine is an alpha2-adrenoceptor agonist indicated for ___________ associated with Multiple sclerosis or spinal cord injury

A

Spasticity

48
Q

Tizanidine is an alpha2-adrenoceptor agonist indicated for spasticity associated with ___________ or ____________

A

Multiple sclerosis

spinal cord injury

49
Q

____________ can be trialled as an adjunct treatment for moderate to severe spasticity in multiple sclerosis if other pharmacological treatments are not effective

A

Cannabis extract

50
Q

Cannabis extract can be trialled as an adjunct treatment for moderate to severe spasticity in ___________ if other pharmacological treatments are not effective

A

multiple sclerosis

51
Q

What are the contraindications to the use of azathioprine? (2)

A
  1. Absent thiopurine methytransferase (TPMT) activity

2. Very low TPMT activity

52
Q

What are the common or very common side effects of azathioprine? (5)

A
  1. Bone marrow suppression (dose-related)
  2. Increased risk of infection
  3. Leukopenia
  4. Pancreatitis
  5. Thrombocytopenia
53
Q

Which side effects of azathioprine may require drug withdrawal? (3)

A
  1. Hypersensitivity reactions (eg malaise, dizziness, vomiting, diarrhea, fever, rigors, myalgia, arthralgia, rash, hypotension, renal dysfunction) ——-> immediate withdrawal of drug
  2. Neutropenia and thrombocytopenia ——> close monitoring and dose adjustment
  3. Nausea (common in early treatment, usually resolves after a few weeks without an alteration in dose); may be managed by using divided daily doses, taking after food, prescribing antiemetics, or temporarily reducing dose
54
Q

Cross-sensitivity and allergy exists between azathioprine and _____________

A

Mercaptopurine

55
Q

Does azathioprine dose need to be adjusted/discontinued in hepatic and/or renal impairment?

A

Yes, consider reducing the dose in both cases

56
Q

What are the monitoring requirements for patients taking azathioprine? (2)

A

Monitor for toxicity throughout treatment:

  1. Monitor FBC weekly (more frequently with higher doses or in severe renal impairment) for the first 4 weeks , thereafter reduce monitoring to at least every 3 months
  2. Blood tests and monitoring for signs of myelosuppression are essential in long-term treatment.
57
Q

In patients taking azathioprine, monitor full blood count weekly (more frequently with higher doses or if severe renal impairment) for first __________, thereafter reduce frequency of monitoring to at least every _________.

A

4 weeks

3 months

58
Q

What additional information should be given to patients taking azathioprine?

A

Patients and their carers should be warned to report immediately any signs or symptoms of bone marrow suppression e.g. inexplicable bruising or bleeding, infection

59
Q

Which drug interactions should be avoided in patients taking azathioprine? (4)

A
  1. Allopurinol and febuxostat (increased risk of hematological toxicity; adjust dose of azathioprine)
  2. Biologics that also suppress the immune system (caution)
  3. ACE inhibitors (increased risk of anemia/leukopenia, monitor)
  4. Live vaccines (BCG, flu, MMR, etc)
60
Q

What is the mechanism of action of amifampridine?

A

Increases ACh concentrations at NMJ by blocking presynaptic fast voltage-gated K channels, thereby prolonging cell membrane depolarization and action potential

Roomies Collab Deck 2: Endocrinology and NeuroPsych (49 decks)

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