Development of respiratory failure in a patient with myasthenic gravis is termed a crisis, since it leads to death if untreated. A crisis may occur due to different mechanisms, which need to be understood if effective therapy is to be given.
Types of crisis:
(1) myasthenic: severe weakness due to accelerated disease activity, which may be precipitated by infection, stress, drugs or trauma. This type is responsive to increasing the dose of anticholinesterase agents.
(2) cholinergic: relative drug overdosage, often due to a spontaneous reduction in disease activity, with nicotinic ganglionic blockade. This requires reducing or stopping drug therapy.
(3) brittle: associated with severe bulbar involvement, often in patients with thymomas, with alternating myasthenic and cholingergic states.
Stage |
Group |
Findings |
I |
incipient crisis |
obvious respiratory difficulty may not be present; bulbar symptoms may be prominent; spirometry may show a decrease in tidal volume and vital capacity |
II |
objective |
evidence of ventilatory distress present |
III |
apneic |
patient stops breathing |
Bulbar signs:
(1) dysarthria
(2) dysphagia
(3) dysphonia (from paresis of vocal cords)
(4) pooling of secretions
Objective signs of ventilatory distress:
(1) decreased vital capacity
(2) increased blood pressure
(3) cyanosis
(4) decreased respirations
Management:
(1) In cholinergic and brittle crisis medications are stopped, while in myasthenic crisis an anticholinesterase agent is given.
(2) Intubation or tracheostomy with respiratory support.
Purpose: To evaluate a myasthenic patient for respiratory crisis.
Specialty: Immunology/Rheumatology
Objective: complications, failure handling and therapy escalation, complication detection, comorbid conditions
ICD-10: G70,