Myasthenia Gravis (Exam 2) Flashcards
Myasthenia Gravis: Definition
An autoimmune disease characterized by fluctuating weakness of certain muscle groups
The course of MG disease is variable
-Short-term remission
-Stabilization
-Severe - Progression
(Difficult to predict)
MG: Risk Factors
Women
Age 10-65
MG: Etiology
Same as every other autoimmune disease
Genetic component with environmental trigger
MG: Pathogenesis
Anti-ACHR Antibodies attack ACH receptors
Decrease in ACH receptor sites at the neuromuscular junction (block ACH from binding)
This prevents ACH molecules from attaching and stimulating muscle contraction
Muscles Involved in MG
Eyes/Eyelids
Facial (drooling)
Speaking
Breathing (Respiratory muscles)
MG: Clinical Manifestations
Fluctuating weakness of skeletal muscle
Strength comes back after resting (sometimes)
Muscles Involved:
-eyes
-facial
-throat
-neck
-breathing
When does MG typically first apear?
After pregnancy
After anesthesia
In MG everything really
Slows down
-talking
-blinking
-weak cough
-difficulty swallowing
Myasthenic Crisis
Develops as the disease progress
Acute exacerbation of muscle weakness triggered by a stressor
Myasthenic Crisis is triggered by
Some sort of stresseor
Myasthenic Crisis: Stressors
Infection
Surgery (anesthesia)
Emotional Distress
Pregnancy
Inadequate pharmacotherapy
Myasthenic Crisis: Major Complication
Breathing muscle weakness (respirotary arrest)
MG: Pharmacotherapy
Immunosuppressants (steroids) (Calm immune response)
Cholinesterase Inhibitors (less ACH broken down)
How do cholinesterase inhibitors help MG?
Prevent inactivation of ACH by cholinesterase
Intensify the effects of ACH released from motor neurons - increases muscle strength
Give cholinesterase inhibitors __ to __ min prior to eating to strengthen swallowing muscles
30 - 45
MG crisis vs Cholinergic Crisis
MG:
-Not enough stimulation or acetylcholine
-Muscles are not stimulated and weak
-Respiratory failure
Cholinergic:
-Too much acetylcholine or neostigmine
-Overstimulation of muscle and muscles are worn out
-Respiratory failure
How do we differentiate between MG Crisis and Cholinergic Crisis
Give EDROPHONIUM
-short acting cholinesterase inhibitor
-increases acetylcholine temporarily
If they are in a MG crisis they will improve because there is an increase in acetylcholine
If they are in a cholinergic crisis they will worsen because they already have too much acetylcholine
