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.
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Stage
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Group
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Findings
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I
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incipient crisis
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obvious respiratory difficulty may not be present; bulbar symptoms may be prominent; spirometry may show a decrease in tidal volume and vital capacity
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II
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objective
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evidence of ventilatory distress present
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III
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apneic
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patient stops breathing
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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.
