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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
Cogan’s lid twitch in MG
While in down gaze, upper eyelid twitches as patient looks up
26
Ice test in MG
At least 2mm of eyelid elevation after 2 minutes of application
27
What can you do in office for MG
Ice test, 2-5 minutes of ice application to reduce appearance of ptosis -cold makes it so that Ach breakdown happens slower
28
Positive ice test
You will see at least 2mm of eyelid elevation after 2 minutes of application
29
Present of an inconsistent deviation along with ptosis and restricted ocular motility
Suspect myasthenia gravis
30
Tests to do for MG
``` Electromyography Sleep test Systemic Ach agents Physical/neuro exam Blood test Diagnostic testing Pulmonary function ```
31
Electromyography in MG
Reduced potentials as EOMs fatigue | -single fiber EMG is most sensitive test for MG
32
Sleep test for MG
Resolution of ptosis and/or ophthalmopathy immediately after 30 min of sleep
33
Systemic Ach agents
Blocks Ach breakdown, should temporaly improve ptosis and eliminate motility restriction - edrophonium chloride - neostigmine
34
Physical/neuro exam MG
Check muscle tone/strength, coordination, touch, and EOMs
35
Blood test for MG
Detect increased Ach receptor Ab
36
Diagnostic testing (MRI/CT)
Rule out Thymoma
37
Ocular Tx for MG
Occlusion Prism Strabismus and/or ptosis surgery
38
Prism for ocular TX of MG
Often not successful
39
Strabismus and/or ptosis surgery in ocular TX for MG
Often not indicated
40
Remission in MG
Spontaneous remission occurs with as many as 30% of patients with ocular myasthenia
41
Systemic TX for MG
- anticholinesterase agents (mestinon or pyridostigmine) - immunosuppressive drugs (prednisone) - thymectomy - plasmapthersis and IV immunoglobulin in severe cases
42
Cure for MG
No cure TX helps relieve signs and symptoms -patients have a relatively high quality of life and normal life expectancy
43
An autoimmune disorder that results in overproduction of thyroid hormone (hyperthyroidism(
Graves
44
Common cause of hyperthyroidism
Graves
45
Types of graves
Graves dermopathy | Graves ophthalmopathy
46
Signs and symptoms of Graves
- 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
AKA thyroid myopathy
Graves ophthalmopathy
48
An autoimmune, inflammatory condition that involves mostly the orbital tissues and muscles
Graves ophthalmopathy | -results from the over production of thyroid hormones
49
The most common cause of spontaneous diplopia in middle age
Graves ophthalmopathy
50
Histology of graves ophthalmopathy
- 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
Characteristics of graves ophthalmopathy
- bilateral - females >males - under 40 - may be inherited
52
Other risk factors of graves ophthalmopathy
Emotion/physical stress Pregnancy Other autoimmune conditions SMOKING
53
Common signs of graves ophthalmopathy
- periorbital congstion/chemosis - pro ptosis - exophthlamos (keratopathy) - lid lag - optic neuropathy - impaired ocular motility
54
What is the proptosis, lid lag, exophthlamos caused by
Sympathetic stimulation of Mueller’s muscle
55
Patient symptoms of ocular ophthalmopathy
Dry/gritty sensation, photophobia, excessive tearing, double vision, pressure behind eyes, vision loss
56
Forced duction in graves
Positive
57
EOMs in graves affected
Inferior rectus is involved most often | IR>MR>SR>LR
58
Inferior rectus being affected in graves
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
What can graves be confused with as fart as EOMs
May be mistake as SR paresis | -will note limited elevation in abduction and adduction with both versions and functions
60
Diplopia in graves
Worse in the morning. Patients may develop compensating head posture to maintain fusio nand avoid diplopia
61
Affected eye in graves
``` Restriction of elevation and abduction Hypotropia in primary position May also see -esotropia or esotropia -cyclotorision ```
62
Tonometry in graves
Do it in primary and upgaze. | -will get a larger number in upgaze (usually at least 3mmHg increas)
63
Hertel exophthalmometer in graves
Measures proptosis
64
Slit lamp eval in graves
Exposure keratopathy
65
Optic nerve eval in graves
Optic neuropathy | Any abnormalities in pupils, color test, or VF
66
Other tests for Graves
CT or orbits, thyroid function tests (T3, T4, TSH)
67
Prognosis of graves
- spontaneous improvement or show reversal with time - deviation may persist with medical control - improvement in ocular motility occur with resolution of orbital edema
68
Ocular treatment in graves
- Prism: fresnel successful - surgery: significant ocular deviations and restriction - artificial tears - cold compresses - smoking cessation
69
Surgery in graves
Significant ocular deviations and restrictions - stability of 6+ months - can be successful in restoring binocular vision
70
Systemic treatment for graves
- 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
7-8x more likely to have graves if
Smoking

Motility Block 11 (4 decks)

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