NMJ diseases and scleroderma

Question 1

Describe the frequency and pathophysiology of myasthenia gravis

Answer 1

Most common NMJ disorder
Autoantibodies to postsynaptic ACh receptor

Question 2

What are the clinical features of myasthenia gravis

Answer 2

Fatigable muscle weakness—ptosis; diplopia; proximal weakness; respiratory muscle involvement (dyspnea); bulbar muscle involvement (dysphagia, difficulty chewing)
Spared reflexes
Worsens w muscle use

Question 3

What other pathologies is MG associated with

Answer 3

Thymoma, thymic hyperplasia

Question 4

Tx of MG

Answer 4

AChE inhibitor administration reverses symptoms (pyridostigmine for tx)

Question 5

Describe the frequency and pathophysiology of Lambert-Eaton myasthenic syndrome

Answer 5

Uncommon
Autoantibodies to presynaptic Ca2+ channel = decreased ACh release

Question 6

Clinical features of Lambert-Eaton

Answer 6

Proximal muscle weakness, autonomic symptoms (dry mouth, constipation, impotence)
Hyporeflexia
Improves w muscle use

Question 7

What other pathologies is Lambert-Eaton myasthenic syndrome associated with

Answer 7

Small cell lung cancer

Question 8

What effect does AChE administration have in Lambert-Eaton myasthenic syndrome have

Answer 8

Minimal

Question 9

Define Raynaud’s phenomenon and where it commonly occurs

Answer 9

Decreased blood flow to skin due to arteriolar (small vessel) vasospasm in response to cold or stress:
colour change from white (ischemia) to blue (hypoxia) to red (reperfusion)
Most often in fingers & toes

Question 10

The difference between Raynaud disease & syndrome

Answer 10

Raynaud disease when 1° (idiopathic)
Raynaud syndrome when 2° to a disease process such as mixed connective tissue disease, SLE, or CREST syndrome (limited form of systemic sclerosis)
Digital ulceration (critical ischemia) is seen in 2° Raynaud syndrome

Question 11

Tx of Raynaud’s

Answer 11

Calcium channel blockers

Question 12

Define scleroderma

Answer 12

Systemic sclerosis. Triad of autoimmunity, noninflammatory vasculopathy, and collagen deposition with fibrosis. Commonly sclerosis of skin, manifests as puffy, taut skin without wrinkles, fingertip pitting

Question 13

Involvement of other systems in scleroderma

Answer 13

Renal (scleroderma renal crisis; treat with ACE inhibitors), pulmonary (interstitial fibrosis, pulmonary HTN), GI (decreased peristalsis & LES tone = dysphagia, heartburn), cardiovascular

Question 14

Who does scleroderma commonly affect

Answer 14

75% females

Question 15

What are the two types of scleroderma

Answer 15

Diffuse and limited scleroderma

Question 16

Define diffuse scleroderma

Answer 16

Widespread skin involvement, rapid progression, early visceral involvement
Associated with anti-Scl-70 antibody (anti-DNA topoisomerase-I antibody) and anti-RNA polymerase III

Question 17

Define limited scleroderma

Answer 17

Limited skin involvement confined to fingers and face
Also with CREST syndrome: Calcinosis cutis, anti-Centromere antibody, Raynaud phenomenon, Esophageal dysmotility, Sclerodactyly, and Telangiectasia
More benign course