Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Neurology Articles > NMJ mimics and chamelons > Flashcards

NMJ mimics and chamelons Flashcards

1
Q

What proteins are essential for NMJ formation and maintenance?

A

Acetylcholine receptors, muscle-specific kinase, low-density lipoprotein 4, and agrin.

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

How does the prevalence of MG compare to chronic inflammatory demyelinating polyradiculoneuropathy?

A

MG is approximately four times as prevalent.

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

What is the most common presenting symptom in MG?

A

Ptosis, often asymmetric, occurring in 50%-70% of patients.

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

What percentage of patients with pure ocular MG develop generalized symptoms within 2 years?

A

Fifty percent.

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

What percentage of patients with pure ocular MG remain pure ocular long-term?

A

Roughly 15%.

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

What percentage of generalized MG cases have AChR antibodies?

A

Approximately 85% of generalized MG cases have AChR antibodies.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

In what percentage of ocular MG cases are AChR antibodies present?

A

Approximately 50% of ocular MG cases have AChR antibodies.

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

What percentage of MG cases have MuSK antibodies?

A

MuSK antibodies are present in 5%-10% of MG cases.

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

What percentage of MG patients are seronegative?

A

Approximately 10% of MG patients are seronegative.

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

What percentage of LEMS patients have anti-VGCC antibodies?

A

Over 90% of LEMS patients have anti-VGCC antibodies.

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

What are the clinical characteristics of LEMS?

A

Proximal lower limb-predominant weakness, autonomic symptoms, and areflexia.

Think myopathy with dry mouth and low reflexes.

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

What is a characteristic feature of LEMS related to exercise?

A

Postexercise facilitation: transient improvement in weakness or reflexes after 10s exercise.

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

What is the result of SNARE protein cleavage by botulinum neurotoxin?

A

Reversible blockade of the NMJ by preventing presynaptic vesicle release.

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

Typical clinical features of botulism?

A

Rapid onset descending flaccid paralysis, ptosis, diplopia, bulbar dysfunction, limb and respiratory weakness.

Usually prominent autonomic symptoms (eg pupils, dry mouth).

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

Toxic causes of NMJ dysfunction?

A

Snake envenomation, black widow spider bites, tick paralysis, organophosphate poisoning.

BOTS.
Black widow toxin= alpha latrotoxin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What medications can cause NMJ dysfunction?

A

Aminoglycosides, macrolides, beta-blockers, and magnesium sulfate and ICIs.

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

What syndrome is associated with immune checkpoint inhibitor therapy?

A

Triple-M syndrome (myositis, myocarditis, MG).

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

What can excessive pyridostigmine use lead to?

A

Exacerbated muscle weakness and cholinergic crisis (>450-600mg/d).

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

What are CMS?

A

CMS are a heterogeneous group of over 30 genetic disorders affecting NMJ components.

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

Associated features of congenital myasthenic syndromes include?

A

Muscle atrophy, facial dysmorphism, scoliosis, limb deformities, epilepsy, cognitive impairment.

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

When should CMS diagnosis be considered in seronegative MG patients?

A

When there’s abnormal repetitive nerve stimulation or single-fibre EMG, and no response to immunotherapy.

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

In what type of myopathies is CMS consideration useful?

A

Undiagnosed myopathies, especially with congenital onset.

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

What is the most common cause of acquired ptosis?

A

Aponeurotic ptosis.

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

What causes aponeurotic ptosis?

A

Dehiscence of the levator aponeurosis from the superior tarsal plate.

The tarsal plate is connective tissue that almost acts like skeletal wiring of the upper and lower eyelids

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

Is aponeurotic ptosis unilateral or bilateral?

A

It may be unilateral or bilateral.

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

What are the risk factors for aponeurotic ptosis?

A

Older age, eyelid trauma, surgery, and contact lens use.

27
Q

What symptom do patients with aponeurotic ptosis report similar to MG?

A

Worsening of ptosis in the evening due to fatigue of Müller’s muscle. (Is it really Muller’s muscle?)

28
Q

What is a key feature of aponeurotic ptosis regarding the eyelid skin crease?

A

Raised upper eyelid skin crease with increased margin-to-crease distance on downgaze.

29
Q

How does aponeurotic ptosis behave on downgaze?

A

Ptosis persists on downgaze.

30
Q

What is notable about levator function in aponeurotic ptosis?

A

Good levator excursion despite ptosis.

31
Q

What condition in the elderly causes intermittent diplopia and may accompany aponeurotic ptosis?

A

Sagging eye syndrome.

32
Q

What causes sagging eye syndrome?

A

Inferomedial migration of lateral rectus due to degeneration of connective tissues.

33
Q

What are the resulting symptoms of sagging eye syndrome?

A

Esotropia and vertical misalignment.

Patients present with intermittent or progressive diplopia on distance vision, but not near vision.

34
Q

What vision condition do patients with sagging eye syndrome experience?

A

Intermittent or progressive diplopia on distance vision.

35
Q

What characterizes floppy eyelid syndrome?

A

Upper eyelid laxity leading to easily evertible lids.

36
Q

What condition is strongly associated with floppy eyelid syndrome?

A

Obstructive sleep apnoea.

37
Q

What is the prevalence of MG in patients with thyroid-associated orbitopathy?

A

MG is 50 times more prevalent in these patients.

38
Q

What are the symptoms of orbital myositis?

A

Acute painful diplopia, chemosis, exophthalmos, and eyelid swelling.

39
Q

What are some causes of orbital myositis?

A

Autoimmune, infective, drug-related, or paraneoplastic processes.
AIDP

40
Q

Name two autoimmune conditions linked to orbital myositis.

A

Sarcoidosis and IgG4-related disease.

41
Q

Which infections can cause orbital myositis?

A

Herpes zoster ophthalmicus and Lyme disease.

42
Q

What is chronic progressive external ophthalmoplegia?

A

A mitochondrial disorder with bilateral ptosis and ophthalmoparesis, sparing pupils. Typically in 3rd -4th decades of life.

43
Q

What symptom do patients with chronic progressive external ophthalmoplegia often lack?

A

Patients often do not have diplopia and are unaware of ptosis.

44
Q

Why might patients be unaware of their ptosis in chronic progressive external ophthalmoplegia?

A

Due to its slowly progressive nature.

45
Q

What are the primary symptoms of oculopharyngeal muscular dystrophy?

A

Ptosis and dysphagia.

46
Q

What additional symptoms may develop in advanced oculopharyngeal muscular dystrophy?

A

Ophthalmoparesis and weakness of tongue, limb girdle, and facial muscles.

47
Q

What genetic mutation causes Oculopharyngeal muscular dystrophy?

A

GCN trinucleotide repeat expansion in exon 1 of the PABPN1 gene.

48
Q

What shared clinical feature can cause confusion between DM1 and MG?

A

Ptosis and facial weakness.

49
Q

Cause of DM1?

A

Trinucleotide repeat expansion in the myotonic dystrophy protein kinase gene.

50
Q

When might phorias decompensate causing diplopia?

A

In mid-life, due to progressive loss.

51
Q

Miller Fisher syndrome is a differential for what condition?

A

Early ocular myasthenia gravis.

52
Q

What are the classic symptoms of Miller Fisher syndrome?

A

Weakness of eye abduction and elevation, pupillary abnormalities, ptosis.

Not sure how accurate this is.

53
Q

What important clues suggest Miller Fisher syndrome?

A

Ataxia, areflexia, and preceding gastrointestinal or respiratory illness.

54
Q

What antibody is commonly found in patients with Miller Fisher syndrome?

A

Anti-GQ1b antibodies.

55
Q

What diagnostic test is typically abnormal in Miller Fisher syndrome?

A

Single-fibre EMG.

56
Q

What EMG finding is common in bulbar-onset MuSK-MG?

A

Fibrillation potentials in affected muscles.

Can also have tongue fasciculations.

57
Q

What characterizes ocular neuromyotonia?

A

Recurrent, brief tonic spasms of extraocular muscles causing intermittent diplopia.

58
Q

What triggers episodes of ocular neuromyotonia?

A

Spontaneous occurrence or after holding eccentric gaze.

59
Q

In what settings does ocular neuromyotonia typically occur?

A

Cranial irradiation or nerve compression.

60
Q

What rare initial manifestation can occur in MuSK-positive MG?

A

Head drop can be the sole initial manifestation.

61
Q

Which conditions can head drop in MuSK-positive MG be confused with?

A

Motor neurone disease, Parkinson’s disease, and myositis.

62
Q

What CMS subtype feature can be mistaken for a distal myopathy?

A

Distal weakness due to agrin mutation.

63
Q

What condition can present in adulthood with limb-girdle weakness and is associated with tubular aggregates?

A

Several types of Congenital Myasthenia syndromes can present in adulthood with limb-girdle weakness and tubular aggregates.

64
Q

What are five categories of myopathy that can cause facial weakness/ptosis?

A

Myotonic dystrophy, FSH, OPMD, mitochondrial, congenital

Neurology Articles (6 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions