Myasthenia Gravis

Question 1

What is Myasthenia Gravis

Answer 1

An autoimmune disease characterized by fluctuating weakness of certain muscle groups

Question 2

What is the course of the disease MG

Answer 2

• Short-term remission
• Stabilization
• Severe, progression

Question 3

Risk factors for MG?

Answer 3

• Age: 10-65 yrs
• Gender: Women

Question 4

MG Pathogenisis

Answer 4

• Antibodies attack ACh receptors
• AKA “anti-AChR antibodies”
• Decrease in ACh receptor sites at the neuromuscular junction
• This prevents ACh molecules from attaching and stimulating muscle contraction

Question 5

MG Manifestations

Answer 5

• Fluctuating weakness of skeletal muscle
• Strength comes back after resting
• Muscles involved
• Eyes/eyelids
• Facial
• Speaking
• Breathing

Question 6

Myasthenic Crisis

Answer 6

• Acute exacerbation of muscle weakness
• Triggered by a stressor:
• Infection
• Surgery
• Emotional distress
• Pregnancy/menses
• Inadequate pharmacotherapy or other drugs

•Major complication

• •Breathing muscle weakness

Question 7

MG Pharmacotherapy

Answer 7

• Immunosuppressants (steroids)
• Cholinesterase inhibitors

Question 8

How do cholinesterase inhibitors work?

Answer 8

Prevent inactivation of ACh by cholinesterase

Intensify the effects of Ach released from motor neurons– increases muscle strength

Give 30 – 45 min prior to eating to strengthen swallowing muscles

Question 9

Are cholinesterase inhibitors a cure or symptomatic relief?

Answer 9

Symptomatic relief

Question 10

Cholinesterase inhibitor (anticholinesterase)

Answer 10

Facilitates transmission of impulses across neuromuscular junctions

Affects both muscarinic and nicotinic receptors

Question 11

What are the effects of Cholinergics and Anticholinergics?

Answer 11

Question 12

Neostigmine: Adverse effects

Answer 12

Muscarinic:

• Increased secretions, GI motility
• Urinary urgency
• Bradycardia
• Bronchial constriction
• Miosis, near-sightedness
• Neuromuscular (nicotinic):
• Therapeutic doses = increased muscle contraction
• Toxic doses = reduced contraction

Question 13

What could Neostigmine toxicity lead to?

Answer 13

cholinergic crisis

Question 14

Cholinergic Crisis Symptoms

Answer 14

• Extreme muscle weakness or paralysis
• S/S of excessive muscarinic stimulation

Question 15

Cholinergic Crisis Treatment

Answer 15

• Mechanical ventilation
• Antidote for muscarinic sx = atropine

Question 16

What should the patient MG patient wear at all times?

Answer 16

Med-alert bracelet

Question 17

MG crisis

Answer 17

• Not enough stimulation or acetylcholine
• Muscles are not stimulated and weak
• Leading to Respiratory failure

Question 18

Cholinergic crisis

Answer 18

• Too much acetylcholine or nystigmine
• overstimulation of muscles and muscles are worn out
• leading to respiratory failure

Question 19

Differentiating between MG and Cholinergic crisis

Answer 19

• Client presents with respiratory insufficiency, extreme muscle weakness
• Give EDROPHONIUM
• A SHORT ACTING CHOLINESTERASE INHIBITOR
• INCREASES ACETYLCHOLINE TEMORARILY
• If they are in a MG crisis, they will improve because there is an increase iin acetylcholine
• If they are in a cholinergic crisis, they will worsen because they already have too much acetylcholine