This document discusses myasthenia crisis, which is a life-threatening condition defined as weakness from myasthenia gravis that requires intubation or delays extubation after surgery. It presents information on the epidemiology, pathophysiology, clinical presentation, diagnosis, and management of myasthenia crisis. Key aspects of management include admission to the intensive care unit, assessment of respiratory function, elective intubation if needed, rapid immunomodulating therapy, careful weaning, and monitoring for complications.

1. Myasthenia Crisis
Dr Pravin Gare
SKH

2. I am a Resident Physician…

3. Amitabh Bachchan

4. Snow White and the Seven
Dwarfs

5. To Discuss…
 Some interesting facts
 Pathology of MG
 Definition
 Clinical presentation
 How to diagnose
 Evaluation and Management

6.  Most common disorder of
neuromuscular transmission.
 Best characterized and understood
autoimmune disorder.
 Fluctuating degree and variable
combination of weakness in ocular,
bulbar, limb and respiratory muscles.
 Antibodies against acetylcholine
receptor and/or receptor associated
proteins.

7. Coined the term
Myasthenia Gravis.
Mya-muscle
Asthenia-weakness
Gravis-serious
Mary Walker
discovered use of
physostigmine in
MGFriedrich Jolly 1895

8. Epidemiology
 10 to 20% of the patients of MG can
have at least 1 episode of crisis in
lifetime
 13 to 20% of the patients , crisis can
be the first manifestation of the
disease.
 Annual risk of myasthenic crisis
among patients with myasthenia
gravis is approximately 2 to 3 percent .

9.  MG occurs at any age, involves either
sex and begins insidiously
 Second and third decades
commonest age of onset in women.
Seventh and eighth decades in men
 Patients complain of specific muscle
weakness, not generalized fatigue

12. Definition
 Myasthenic crisis is a life-threatening
condition, which is defined as
weakness from acquired myasthenia
gravis that is severe enough to
necessitate intubation or to delay
extubation following surgery

13.  Respiratory failure can be because of
respiratory muscle weakness and/or
oropharyngeal muscle weakness
leading to upper airway obstruction .

14. Pathophysiology

15. Clinical presentation
 Skeletal muscle weakness with true
muscle fatigue.
 c/o specific muscle weakness
 Most commonly worse later in a day or
evening or after exercise.
 Earlier in the disease symptoms may
be absent on awakening.

16.  More than 50% patients present with
ocular symptoms of ptosis and/or
diplopia, about half will progress to
generalized disease in 2 years.
 15% patients will present with bulbar
weakness c/o dysarthria dysphagia
and fatigable chewing.
 Less than 5% will present with
proximal limb muscle weakness.

17. Crisis..
 Increasing generalized or bulbar
weakness as a warning.
 Respiratory insufficiency can be out of
proportion to limb or bulbar weakness.
 In a report of 44 patients who
developed 63 episodes of myasthenic
crises, the crisis began with
generalized weakness, bulbar
symptoms, or weakness of respiratory
muscles in 76, 19, and 5 percent,
respectively

18.  Generalized weakness can mask
signs of respiratory distress.
 Weak respiratory muscles may fatigue
suddenly and can lead to respiratory
collapse.
 Bulbar weakness may cause
aspiration upper airway obstruction
leading to intubation.

19. Precipitants
 Concurrent infections
 Pregnancy
 Surgical intervention
 Tapering of immunosuppressive drugs
 Drugs

21. Diagnosis
 Simple bedside tests
 Lab investigations
 Electromyographic studies

24.  Nursing recommendation: Nurses
should understand and explain the
“ice pack test” and diagnostic imaging
to the patient and family to lessen fear
and anxiety and elicit cooperation and
participation (Level 2).

26. AANN
 Nursing recommendation: Nurses
should know the adverse events
associated with diagnostic testing in
MG and how to manage those side
effects as needed. Nurses should
monitor for results and adverse events
associated with the use of
edrophonium for diagnostic testing in
MG and manage adverse events
appropriately (Level 2).

29. Nursing recommendation: Nurses should
be familiar with electrodiagnostic testing
in MG. Nurses should prepare patients for
their experience, including the likelihood
of some discomfort (Level 2).

30. Management
 Admit to ICU
 Assessment of respiratory function
 Elective intubation
 Rapid therapy
 Immunomodulating therapy
 Careful weaning
 Taking care of complications

31. Admit to ICU
 Rapidly increasing weakness
secondary to an exacerbation of MG
 Frequent monitoring
 Symptoms of dyspnoea, severe
dysphagia with weak cough and
difficulty in clearing secretions.
 Signs of respiratory muscle weakness
such as poor respiratory effort ,
shallow breathing , paradoxical
breathing

32. Measures of respiratory muscle
functon

34. Vital capacity
 The VC reflects the mechanical
function of both inspiratory and
expiratory muscle strength. It can be
performed easily at the bedside.
 Some experts recommend assessing
both supine and sitting VC, as
diaphragmatic weakness is more
apparent on the supine measurement.

35. MIP
 Provides information on inspiratory muscle
strength. The patient is instructed to
maximally inhale against a closed valve and
the force/pressure that is generated at the
mouth is recorded.
 Inspiration is a negatively generating force
and thus values are recorded as negative
numbers; a MIP below one-third of normal
(eg, 0 to -30 cmH2O) predicts severe
respiratory muscle weakness and probable
hypercarbic respiratory failure while a MIP of
-60 cmH2O is usually associated with a weak
cough only.

37.  Monitoring spo2
 ABG
 Insensitive measures of respiratory
muscle weakness because they often
develop only after the onset of life-
threatening respiratory failure.
 However, the development of
progressive hypercarbic respiratory
acidosis despite therapy may provide
supportive evidence that prompts early
rather than late intubation.

39.  Nursing recommendation: Nurses
should administer drugs that may
worsen MG with caution. Review
medication profiles with the
pharmacist and licensed independent
provider (Level 3).

40. Elective intubation
 VC falls below 15 to 20 mL/kg
 MIP is less negative than -25 to -30
cmH20 (ie, between 0 and -30 cmH20)
 clinical signs of respiratory distress,
progressive hypercapnic respiratory
acidosis despite therapy, and
inadequate secretion clearance .

41.  Succinyl choline can be used but dose
required is high.
 Rapid sequence intubation.
 NIV is avoided in MS
 Use of chest physio , suction and
bronchodilators
 Cholinesterase inhibitors should be
stopped after intubation.

42. Treatment
 Rapid therapy – IV IG ,
Plasmapheresis
 Immunomodulators
 Anticholinesterase inhibitors
 Thymectomy

51. Weaning off ventilator
 Principles of weaning should be the same
as for the general population. However,
particular attention should be paid to
measuring indices of respiratory muscle
strength and secretion clearance.
 SBTs should only begin after the patient has
started treatment with plasma exchange or
IVIG and the patient shows evidence of
improving respiratory muscle strength, ie,
with a VC >15 to 20 mL/kg and a MIP more
negative than -25 to -30 cmH2O (eg, -30 to -
60 cmH2O)

52.  Adequate cough and less secretions.
 Closely monitor following extubation
for early failure using VC and MIP
measurements to detect those who
may need reintubation.
 Tracheostomy

53. Complications
 Pneumonia, bronchitis, urinary tract infection,
 Colitis caused by Clostridium difficile,
bacteremia, and sepsis.
 Patients with myasthenic crisis are at
increased risk for vascular complications
including deep vein thrombosis, heart failure,
acute myocardial infarction, cardiac
arrhythmias, and cardiac arrest.
 There are also several case reports of stress-
induced cardiomyopathy (Takotsubo
cardiomyopathy) associated with myasthenic
crisis