Myasthenia gravis

1. MYASTHENIA GRAVIS

2. INTRODUCTION
The name myasthenia gravis , which is Latin
and Greek in origin ,means “grave,or serious
,muscle weakness “. Autoimmune disease
affecting the neuromuscular junction .
*Its not a brain disorder – brain functions
normally.
Characterized by fluctuating muscle
weakness and fatigability.

3. DEFINITION
Myasthenia gravis is an autoimmune
disorder affecting the myoneural junction, is
characterized by varying degree of weakness
of the voluntary muscles.

4. Anatomy & Physiology

5. Anatomy
The anatomy of NMJ consists of following
parts:
•Pre-synaptic membrane : it contains pre-
junctional acetylcholine receptors and
active zone
•Synaptic cleft : lies between the muscle
endplate and nerve terminal which are held
in tight by basal lamina

6. Conti…
•Post-synaptic membrane : at the post –
synaptic membrane area overlying the
nerve terminal is called muscle endplate.
The membrane here is thrown into primary
and secondary cleft
•Contractile apparatus : it is formed by thin
actin , thick myosin filaments tropomyosin
& troponin.The shortening of this
apparatus causes the contraction of the
muscle

7. Physiology
Neuromuscular junction is specialized on
the nerve side & on the muscle side to
transmit & receive chemical messages
Each motor neurons runs without
interuption from the ventral horn of spinal
cord to NMJ as a large myelinated axon
As it approaches muscle it branches to
contract many muscle cells together into
functional group known as Motor unit

8. INCIDENCE
MG affects 14 per 100,000 people in the
United States .
Can affect any age group .
Women – peak incidence 20s to 30s.
Men- peak incidence 50s to 60s.

9. CAUSES
oIdiopathic.
oAutoantibodies that destroys acetylcholine
receptors.
oThymus tumors found in 15% of patients .

10. RISK FACTORS
It include:
Female gender and age under 40years.
Male gender and age under 60years.
Other autoimmune disorders .

11. PATHOPHYSIOLOGY
DUE TO AUTOIMMUNE RESPONSE
DEVELOPMENT OF AUTOANTIBODIES
ANTIBODIES ATTACK ACETYLCHOLINE [ACT]
RECEPTORS AT THE MOTOR END PLATE

12. CONTI…
ACT AGAINST THE NICOTINIC ACETYLCHOLINE RECEPTOR
IMPAIR THE ABILITY OF ACETYLCHOLINE To BIND THE
RECEPTORS
RESULTING IN VOLUNTARY MUSCLE WEAKNESS
THAT ESCALATES WITH CONTINUED ACTIVITY

13. CLINICAL MANIFESTATIONS
Affects any voluntary muscle groups
Eye , face, throat , neck, limb muscles
The hallmark of myasthenia gravis is
fatigability
Dysphagia
Ptosis
Diplopia
Nasal sounding speech
Worsening muscle weakness

14. ASSESSMENT & DIAGNOSTIC EVALUATION
ASSESSMENT
History
Physical examination
Diagnostic Evaluation
Edrophonium test [Tensilon]
Blood analysis
Ice pack test
Repetitive nerve stimulation
Pulmonary function tests
Single –fiber electromyography (EMG)
Imaging scans

15. Physical Examination
Muscle strength and tone
Coordination
Sense of touch
Impairment of eye movements

16. Edrophonium test
Injection of the chemical
edrophonium(Tensilon) may result in a
sudden, althugh temporary , improvement
in muscle strength –an indication that
patients may have myasthenia gravis

17. Blood Analysis
A blood test may reveal the presence of
abnormal antibodies that disrupt the
receptor sites where nerve impulses signal
muscles to move

18. Ice Pack Test
Cooling may improve neuromuscular
transmission. In a patient with myasthenia
gravis who has ptosis , placing ice over an
eyelid will lead to cooling of the lid , which
leads to improvement of the ptosis

19. Repetitive Nerve Stimulation
Repetitive nerve stimulation , which
repeatedly stimulates a person’s nervers
with small pulses of electricity to tire
specific muscles.
Muscle fibers do not respond as well to
repeated electrical stimulation .

20. Single –Fiber Electromyography
(EMG)
•It considered the most sensitive test for
myasthenia gravis , detects impaired
nerve –to-muscle transmission .
CT Or MRI : Its shows thymus
enlargement

21. MANAGEMENT

22. Medical Management
•Pharmacological management
•Non pharmacological management

23. Pharmacological Management
•Immunosuppressive Therapy
-Prednisone
-Azathioprine
•Acetylcholinesterase Inhibitors
-First line therapy
-Neostigmine bromide (Pyridostigmine)
-Edrophonium chloride (Tensilon)
•Plasmapheresis
•Immunoglobulin Therapy

24. Non- Pharmacological
Management
Eat small meals and snacks 5-6 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
Alternative sips of liquid to avoid food from
sticking
AVOID eating chewy or dry crumbly foods

25. Surgical Management
•Thymectomy : (surgical removal of the
thymus gland) can produce antigen –
specific immunosuppression and result in
clinical improvement .

26. Dietary Management
Reduce protein intake to 10 percent of
total calories ; replace animal protein as
much as possible with plant protein
Eliminate milk and milk products
(substitute other calcium sources )
Eat more fruits and vegetables (make sure
that they are organically grown)
Take ginger

27. Nursing Management
Maintain patient airway
Assess swallowing to prevent aspirations
Keep appropriate equipment available at the
bedside
Provide energy conservation measures
Consult with speech and language therapist
if weakening facial muscles impact
communication
Monitor I/O, serum albumin levels, and daily
weights
Administer Medications as per order

28. Priority Needs
oNeed to maintain normal breathing pattern
oNeed to improve physical mobility
oNeed to improve verbal communication
oNeed to reduce muscle weakness

29. Nursing Diagnosis
1. Ineffective breathing pattern related to
intercoastal muscle weakness
2. Impaired physical mobility related to voluntary
muscle weakness
3. Impaired verbal communication related to
weakness of the larynx , lips , mouth , pharynx
and jaw
4. Risk for aspiration related to weakness of the
bulbar muscles
5. Disturbed sensory perception related to ptosis ,
and decreased eye movements

30. Complications
Myasthenic crisis
Thymus tumors
Thyroid problems
Lupus
Rheumatoid arthritis

31. Health Education
Teach patient / family about disease
condition
Teach patient about their medications,
uses, dosages , etc
Advice patient to improve physical
movement
Teach the patient to do speech therapy
Instruct the patient continue the follow up

32. Conclusion
Myasthenia gravis is an autoimmune
disease affecting the neuromuscular
junction . It causes muscle weakness .
Myasthenia gravis may affect individuals of
any age and we have largest experience in
India for treatment of Myasthenia gravis