Myasthenia Gravis and Multiple Sclerosis Flashcards Preview

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Flashcards in Myasthenia Gravis and Multiple Sclerosis Deck (46)
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1

Most common disorder of neuromuscular transmission

Myasthenia gravis

2

What is myasthenia gravis?

Autoimmune disorder of the acetylcholine receptors at the NMJ causing weakness and fatiguability of muscles

3

Distribution of myasthenia gravis

20-30s (more females)
60s-80s (more males)

4

Types of myasthenia gravis

Ocular (can progress to next)
Generalized

5

What might play a role in myasthenia gravis?

Thymus (maybe due to similar cells that are on skeletal muscles)-do CT or MRI of chest
Most pts have thymus hyperplasia or thymoma

6

Hallmark of myasthenia gravis

Fluctuating weakness in ocular, bulbar (speech, chewing, swallowing), limb or respiratory muscles

7

Sxs of myasthenia gravis

Fluctuating weakness and fatigue of specific muscle groups (worse at end of day or after exercise)
-ptosis/diplopia
-dysarthria, dysphagia, chewing difficulties
-myasthenic sneer (facial muscle weakness)
-Dropped head syndrome and limb weakness in arms more than legs
-Myasthenic crisis due to resp muscles

8

Triggers than can worsen myasthenia gravis

Hot temps
Surgery
Emotional stress
Illness
Menstruation, pregnancy, childbirth
Medication

9

Drugs to avoid with myasthenia gravis

Fluoroquinolones
BBs
Hydroxychloroquine (Plaquinil)

10

How to diagnose myasthenia gravis

History and physical
Maintain upward gaze x 1 min (ptosis due to fatigability)
Ice pack test in pt with ptosis should improve sxs
NCS and EMG show decrease response on repetitive nerve stimulation and fatigability

11

Serologic tests for myasthenia gravis

Autoantibodies:
AChR Ab (Ach receptor antibodies)
MuSK Ab (muscle specific kinase antibodies)

12

Edrophonium (Tensilon) Test

Used to be used for myasthenia gravis (prolongs presence of Ach to stimulate limited number of AChR and it shows immediate increase in muscle strength)

13

How to tell generalized MG from ALS

ALS does not have ptosis or diplopia

14

Lambert-Eaton myasthenic syndrome

Reduced Ach release in NMJ
Autoimmune disease often associated with malignancy (SCLC)
Proximal muscle weakness and sxs worse in AM and improve with exercise!!

15

Symptomatic tx for myasthenia gravis

Oral acetylcholinesterase inhibitor (Pyridostigmine/Mestinon) similar to Tensilon so short acting

16

Chronic immunotherapies for myasthenia gravis

Immunomodulating agents (glucocorticoids or azathioprine)

17

Rapid (short acting) immunotherapies for myasthenia gravis

Plasmapheresis/plasma exchange-directly removes AChR antibodies from circulation
IVIG-pooled immunoglobulin from thousands of donors
(can be used as bridge for chronic therapy)

18

Last choice for myasthenia gravis tx

Thymectomy in select pts (remission is possible)

19

Use of pyridostigmine/Mestinon

Limb and bulbar sxs improve more than the ocular sxs
Allows prolonged effect of Ach strength
Titrate and watch for cholinergic SEs (not great for generalized MG tho)

20

Epidemiology of multiple sclerosis

Usually diagnosed 15-45 YO
More females
Leading cause of permanent disability in young adults

21

What is multiple sclerosis?

Immune mediated attack on axons and myelin sheaths of nerve fibers causing plaques or demyelination and affects nerve transmission

22

Imaging test of choice for MS

MRI with and without contrast of brain (revealing plaques within myelin)

23

Hallmark of MS

Symptomatic episodes occur months-yrs apart and different anatomic locations (based on clinical findings alone or clinical findings and MRI)
*separation of time and space

24

Possible risk factors for MS

Viral infections
Geographic factors related to latitude
Sunlight and Vit D (may be protective)
Genetic susceptibility
Tobaccos

25

Types of MS

Relapsing-remitting disease
Secondary progressive
Primary progressive
Clinically isolated syndrome (1st attack-no prior sxs but now have acute symptomatology)

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Relapsing-remitting MS

Most common type of MS
Clearly defined relapses with full recovery or some deficit

27

Secondary progressive MS

Initially RRMS with gradual worsening
Usually 10-20 yrs after dx

28

Primary progressive MS

Progressive sx increase from disease onset with no remission

29

What is Uhthoff phenomenon?

Specific to MS-transient worsening due to elevated body temp

30

Typical patient with RRMS

Young adults with episodes (relapses/attacks/exacerbations) of CNS dysfunction
Paresthesia
Optic neuritis
Weakness
Sxs develop over hrs-days and resolve wks-mos