myasthenia_gravis diagnosis and management

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1. Myasthenia Gravis
“Grave Muscle Weakness”

3. Myasthenia Gravis
Autoimmune disease affecting the neuromuscular
junction
Not a brain disorder – brain functions normally
Characterized by fluctuating muscle weakness and
fatigability
Disease may be generalized or ocular specific

4. Pathophysiology
Antibodies attack Acetylcholine (ACH) receptors
at the motor end plate
Decreased number of (ACH) receptor sites at
neuromuscular junction
Prevents neurotransmitter (ACH) from attaching
and stimulating muscle contraction
Resulting in loss of muscle strength

7. Causes
No single cause has been identified
Abnormal thymus tissue found in most patients
with MG
Thymic tumors found in 15% of patients
Virus infections have been found in some cases
and are a suspected cause

8. Incidence
Occurs in all races
MG affects 14 per 100,000 people in the United
States
Can affect any age group
Women – peak incidence 20's to 30's
Men – peak incidence 50's to 60's
Three times more common in women than men
Juvenile onset or over the age of 70 onset is
extremely rare

9. Genetic Factors
Myasthenia Gravis is not a genetically inherited
disease
Some families appear to carry a gene that
increases the risk for developing the disease
No specific gene has been identified and there are
no tests for genetic screening

10. Diagnosis
Edrophonium test (Tensilon)
Blood analysis
Repetitive nerve stimulation
Single-fiber electromyography (EMG)
Imaging scans

11. Tensilon Test
Injection may result in a sudden, although
temporary, improvement in muscle strength — an
indication of myasthenia gravis. Acts to block an
enzyme that breaks down acetylcholine, the
chemical that transmits signals from nerve endings
to muscle receptor sites.

12. Signs and Symptoms
Affects any of the muscles that you control voluntarily,
certain muscle groups are more commonly affected than
others
Eye, face, throat, neck, limb muscles
Difficulty speaking (dysarthria)
Difficulty swallowing (dysphagia),
Drooping eyelids (ptosis)
Double vision (diplopia)
Nasal-sounding speech and weak neck muscles that give
the head a tendency to fall forward or backward.
 

13. Signs and Symptoms
Symptoms tend to progress over time, usually
reaching their worst within a few years after the
onset of the disease
Worsening muscle weakness with repeat activity

14. Exacerbation Trigger Factors
Infection
Stress
Fatigue
Cathartics (laxatives)
Heat (sauna, hot tubs, sunbathing)

15. Diet/Nutrition
Eat small meals and snacks five to six times a day
Avoid using low fat or diet products when possible
Avoid eating lemons or tonic water
Eat warm rather than hot food
Runny or puree diet when swallowing is difficult
Alternate sips of liquid to avoid food from sticking
AVOID eating chewy or dry crumbly foods

16. Medications/Treatment
Immunosuppressive Therapy
Prednisone
Azathioprine
Acetylcholinesterase Inhibitors
First line of therapy
Neostigmine bromide (Pyridostigmine)
Edrophonium chloride (Tensilon)

17. Medications/Treatment
Plasmapheresis
Immunoglobulin Therapy
Thymectomy

18. Myasthenic Crisis VS.
Cholinergic Crisis
Myasthenic Crisis
Under medication
Increased HR/BP/RR
Bowel and bladder
incontinence
Decreased urine output
Absent cough and swallow
reflex
May need mechanical
ventilation
Temporary improvement of
symptoms with administration
of Tensilon
Cholinergic Crisis
Overmedication
Decreased BP
Abd cramps
N/V, Diarrhea
Blurred vision
Pallor
Facial muscle twitching
Constriction of pupils
Tensilon has no effect
Symptoms improve with
administration of
anticholinergics (Atropine)

19. Nursing Interventions
Maintain patent airway
Assess swallowing to prevent aspiration
Keep appropriate equipment available at the
bedside: Oxygen, suction, Ambu bag,
endotracheal intubation
Promote energy conservation measures
Consult Physical Therapy for medical equipment
needs (i.e.walkers, wheelchairs)

20. Nursing Interventions
Consult OT for assistive devices to facilitate ADLs
Consult with speech and language therapist if
weakening facial muscles impact communication
Monitor I/O, serum albumin levels, and daily weights
Know the signs and symptoms of both Myasthenic
Crisis and Cholinergic Crisis
Administer Medications
Immunosuppressants: Prednisone, Imuran
Cholinesterase Inhibitors: Pyridostigmine

21. Patient Teaching
Teach patient/family disease process, complications, and
treatments
Teach patient about their medications uses dosage etc
Teach medications to use with caution d/t muscle
exacerbation
Beta blockers, calcium channel blockers, quinine, quinidine,
procainamide, some antibiotics, neuromuscular blocking agents
Avoid certain medications
D-penicillinamine, A-interferon, botulinum toxin

22. Patient Teaching
Teach s/sx of both Myasthenic Crisis and Cholinergic Crisis
Help patient plan daily activity to coincide with energy peaks
Stress need for rest periods
Explain that exacerbations, remissions, and daily fluctuations
are common
Avoid strenuous exercise, stress, infection, exposure to hot or
cold temperatures
Teach patient to wear medic-alert bracelet
Provide Info on Support groups
www.myasthenia.org

23. Prognosis
Chronic disease with periods of exacerbation and
sometimes remissions
Disease course is highly variable
Symptoms respond well to treatment and in most
cases the patient can live a normal or nearly
normal life
Ocular Myasthenia has the best prognosis