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Motility Block 11 > Myasthenia Gravis And Graves > Flashcards

Myasthenia Gravis And Graves Flashcards

1
Q

An autoimmune, neuromuscular disorder by the fatigability of voluntary striated muscles

A

Myasthenia gravis

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2
Q

When does myasthenia gravis occur

A

Secondary to the loss of Ach receptors at the NMJ=failure to release/produce Ach

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3
Q

Epidemiology of MG

A
  • 20-50/100,000 in the US
  • more females
  • women under 40, men over 60
  • neonatal or congenital
  • can occur at any age
  • many experience initial symptoms during emotional upset
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4
Q

Etiology of MG

A

Immune system release Ab that block and destroy Ach recepto sites along with tyrosine kinase

  • fewer receptor sites lead to less nerve signals
  • muscle weakness
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5
Q

Thymus and MG

A

Thymus gland may trigger Ab production,. Studies show that thymus is larger in most MG patients

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6
Q

Hallmark of MG

A

Muscle weakness that worsens after periods of activity and improves after periods of rest
-known as the “great mimicker”

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7
Q

2 forms of MG

A

Generalized and ocular

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8
Q

Generalized MG

A

Fatigue and muscle weakness

Ocular may present initially

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9
Q

Ocular MG

A

Only lid and EOM abnormalities

No systemic signs, however it is often a precursor to generalized MG

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10
Q

Generalized MG symptoms

A

Weakness of arms and leg muscles

Difficulties with speech, chewing, swallowing, breathing

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11
Q

Symptoms of ocular MG

A

Ptosis
Diplopia
Nystagmoid movements

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12
Q

Ptosis in ocular MG

A

Most common feature
Often due to a palsy of the lavatory muscle
Usually unilateral
Progressive: usually worse later in the day

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13
Q

Diplopia in ocular MG

A

20-40% will have diplopia as a complaint

Horizontal or vertical, no definite pattern

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14
Q

Disease of the skeletal muscle and can mimic many ocular musculature paresis

A

MG

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15
Q

What muscles show problems with MG

A 
Orbicularic oculi 
Masseter muscle 
Sternocleidomastoid 
Tongue 
Diaphragm
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16
Q

Orbicularis oculi in MG

A

Unable to resist forced eye opening

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17
Q

Masseter muscle in MG

A

Unable to open jaw

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18
Q

Sternocleidomastoid in MG

A

Present with head droop

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19
Q

Tongue in MG

A

Unable to push sides of mouth, poor gag response

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20
Q

Diaphragm in MG

A

Ventilate depression and death

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21
Q

Myasthenia crisis

A

Occurs when the muscles are too weak to control breathing

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22
Q

Associations with MG

A

Thymomas
Thymus hyperplasia
Thyroid disease
Other autoimmune disorders common (rheumatoid factor present)

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23
Q

Ocular Dx of MG

A
  • use old photos

- fatigue in ocular movements

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24
Q

Ptosis occurs when in MG

A

With prolonged up gaze or rapid open/closing of eyes

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25
Q

Cogan’s lid twitch in MG

A

While in down gaze, upper eyelid twitches as patient looks up

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26
Q

Ice test in MG

A

At least 2mm of eyelid elevation after 2 minutes of application

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27
Q

What can you do in office for MG

A

Ice test, 2-5 minutes of ice application to reduce appearance of ptosis
-cold makes it so that Ach breakdown happens slower

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28
Q

Positive ice test

A

You will see at least 2mm of eyelid elevation after 2 minutes of application

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29
Q

Present of an inconsistent deviation along with ptosis and restricted ocular motility

A

Suspect myasthenia gravis

30
Q

Tests to do for MG

A 
Electromyography 
Sleep test 
Systemic Ach agents 
Physical/neuro exam 
Blood test 
Diagnostic testing 
Pulmonary function
31
Q

Electromyography in MG

A

Reduced potentials as EOMs fatigue

-single fiber EMG is most sensitive test for MG

32
Q

Sleep test for MG

A

Resolution of ptosis and/or ophthalmopathy immediately after 30 min of sleep

33
Q

Systemic Ach agents

A

Blocks Ach breakdown, should temporaly improve ptosis and eliminate motility restriction

  • edrophonium chloride
  • neostigmine
34
Q

Physical/neuro exam MG

A

Check muscle tone/strength, coordination, touch, and EOMs

35
Q

Blood test for MG

A

Detect increased Ach receptor Ab

36
Q

Diagnostic testing (MRI/CT)

A

Rule out Thymoma

37
Q

Ocular Tx for MG

A

Occlusion
Prism
Strabismus and/or ptosis surgery

38
Q

Prism for ocular TX of MG

A

Often not successful

39
Q

Strabismus and/or ptosis surgery in ocular TX for MG

A

Often not indicated

40
Q

Remission in MG

A

Spontaneous remission occurs with as many as 30% of patients with ocular myasthenia

41
Q

Systemic TX for MG

A
  • anticholinesterase agents (mestinon or pyridostigmine)
  • immunosuppressive drugs (prednisone)
  • thymectomy
  • plasmapthersis and IV immunoglobulin in severe cases
42
Q

Cure for MG

A

No cure
TX helps relieve signs and symptoms
-patients have a relatively high quality of life and normal life expectancy

43
Q

An autoimmune disorder that results in overproduction of thyroid hormone (hyperthyroidism(

A

Graves

44
Q

Common cause of hyperthyroidism

A

Graves

45
Q

Types of graves

A

Graves dermopathy

Graves ophthalmopathy

46
Q

Signs and symptoms of Graves

A
  • enlargement of the thyroid (goiter)
  • weight loss
  • heat sensitivity-increase in perspiration with warm, moist skin
  • change in menstrual cycle
  • fatigue
  • thick, red skin
  • rapid, irregular heartbeat
  • bulging eyes
  • erectlie dysfunction
47
Q

AKA thyroid myopathy

A

Graves ophthalmopathy

48
Q

An autoimmune, inflammatory condition that involves mostly the orbital tissues and muscles

A

Graves ophthalmopathy

-results from the over production of thyroid hormones

49
Q

The most common cause of spontaneous diplopia in middle age

A

Graves ophthalmopathy

50
Q

Histology of graves ophthalmopathy

A
  • Ab bind to thyroprtiein receptors on thyroid endothelial cells to stimulate excess production of thyroid hormone
  • condition results in build up of carbs in muscles and tissues behind the eyes
  • changes in the lymphocytic infiltration and fibrosis of muscles which impair their elasticity
  • enlargement of EOMs
  • reduces the elasticity and motility of affected EOMs and produces an incomitant deviation
51
Q

Characteristics of graves ophthalmopathy

A
  • bilateral
  • females >males
  • under 40
  • may be inherited
52
Q

Other risk factors of graves ophthalmopathy

A

Emotion/physical stress
Pregnancy
Other autoimmune conditions
SMOKING

53
Q

Common signs of graves ophthalmopathy

A
  • periorbital congstion/chemosis
  • pro ptosis
  • exophthlamos (keratopathy)
  • lid lag
  • optic neuropathy
  • impaired ocular motility
54
Q

What is the proptosis, lid lag, exophthlamos caused by

A

Sympathetic stimulation of Mueller’s muscle

55
Q

Patient symptoms of ocular ophthalmopathy

A

Dry/gritty sensation, photophobia, excessive tearing, double vision, pressure behind eyes, vision loss

56
Q

Forced duction in graves

A

Positive

57
Q

EOMs in graves affected

A

Inferior rectus is involved most often

IR>MR>SR>LR

58
Q

Inferior rectus being affected in graves

A

Fibrous union between the inferior rectus and inferior oblique may lead to a restriction in upgaze and hypotropia of the affected eye
-severe cases: eye is tethered down

59
Q

What can graves be confused with as fart as EOMs

A

May be mistake as SR paresis

-will note limited elevation in abduction and adduction with both versions and functions

60
Q

Diplopia in graves

A

Worse in the morning. Patients may develop compensating head posture to maintain fusio nand avoid diplopia

61
Q

Affected eye in graves

A 
Restriction of elevation and abduction
Hypotropia in primary position 
May also see
-esotropia or esotropia
-cyclotorision
62
Q

Tonometry in graves

A

Do it in primary and upgaze.

-will get a larger number in upgaze (usually at least 3mmHg increas)

63
Q

Hertel exophthalmometer in graves

A

Measures proptosis

64
Q

Slit lamp eval in graves

A

Exposure keratopathy

65
Q

Optic nerve eval in graves

A

Optic neuropathy

Any abnormalities in pupils, color test, or VF

66
Q

Other tests for Graves

A

CT or orbits, thyroid function tests (T3, T4, TSH)

67
Q

Prognosis of graves

A
  • spontaneous improvement or show reversal with time
  • deviation may persist with medical control
  • improvement in ocular motility occur with resolution of orbital edema
68
Q

Ocular treatment in graves

A
  • Prism: fresnel successful
  • surgery: significant ocular deviations and restriction
  • artificial tears
  • cold compresses
  • smoking cessation
69
Q

Surgery in graves

A

Significant ocular deviations and restrictions

  • stability of 6+ months
  • can be successful in restoring binocular vision
70
Q

Systemic treatment for graves

A
  • radioactive iodine therapy
  • corticosteroids
  • anti-thyroid drugs
  • thyroidectomy
  • ocular symptoms do not always improve with diseases treatment. Ocular signs may worsen for 3-6 months
71
Q

7-8x more likely to have graves if

A

Smoking

Motility Block 11 (4 decks)

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