This powerpoint presentation will help to understand the concept of Myasthenia Gravis.

2. Myasthenia
Gravis
Ms Tarika Sharma
Assistant Professor
MMCON, MMU, Ambala

3. INTRODUCTION
The most common primary disorder of
neuromuscular transmission.
Usual cause is an acquired immunological
abnormality
But some cases result from genetic
abnormalities at the neuromuscular
junction.

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

5. NEUROMUSCULAR TRANSMISSION
The normal neuromuscular junction releases
acetylcholine (ACh) from the motor nerve terminal in
discrete packages
The ACh quanta diffuse across the synaptic cleft and
bind to receptors on the folded muscle end-plate
membrane.
Stimulation of the motor nerve releases many ACh
quanta that depolarize the muscle end-plate region and
then the muscle membrane causing muscle contraction.

8. PATHOPHYSIOLOGY
Normally, a chemical impulse precipitates the release of
acetylcholine from vesicles on the nerve terminal at the
myoneuraljunction.
The acetylcholine attaches to receptor sites on the motor
end plate, stimulating muscle contraction.
Continuous binding of acetylcholine to the receptor site is
required for muscular contraction to be sustained.

9. PATHOPHYSIOLOGY…
In myasthenia gravis, autoantibodies directed at the
acetylcholine receptor sites impair transmission of
impulses across the myoneural junction.
Therefore, fewer receptors are available for stimulation,
resulting in voluntary muscle weakness that escalates
with continued activity.

10. THE THYMUS IN MYASTHENIA GRAVIS
80% of persons with myasthenia gravis have
either thymic hyperplasia or a thymic tumor and
the thymus gland is believed to be the site of
antibody production.

12. Factors that worsen myasthenic symptoms
Emotional upset
Systemic illness
Hypothyroidism or hyperthyroidism
Pregnancy
The menstrual cycle
Drugs affecting neuromuscular transmission,
Increase in body temperature

13. TYPES
Ocular M.G: weakness of eye and lid
muscles only.
Bulbar M.G: Involves breathing, swallowing
and speech :C.N 9th & 12th
Generalized M.G: Involves the proximal
muscles of limbs and neck, usually with
ocular and/ or bulbar symptoms.

14. Clinical Manifestations
Diplopia and Ptosis

15. Clinical Manifestations…
Weakness of the muscles of the face and the throat,
and generalized weakness. Weakness of the facial
muscles results in bland facial expression.
Laryngeal irritation causes voice impairment and
dysphonias and increases the patient’s risk for
choking and aspiration.

16. Clinical Manifestations…
Generalized weakness of all the extremities and
the intercoastal muscles resulting in decreased
respiratory capacity and vital capacity.
Myasthenia gravis is purely a motor disorder with
no effect on the sensation and coordination.

17. CLINICAL PRESENTATION ( Cont..)
Sleepy mask like expression; horizontal
smile ( cranial nerves of face involvement )
Dysphonia (nasal quality to speech )
Easy fatigability
Weakness in proximal muscles (difficulty
climbing stairs, doing deep knee bends and
raising arms above head.)

19. DIAGNOSIS
History
Physical examination
The Edrophonium Chloride (Tensilon) Test
Ice Test
Anti – Ach- Antibodies titer ( elevated in 90% cases)

20. The EdrophoniumChloride (Tensilon) Test
Tensilon ( short acting anticholinesterase which inhibit
cholinesterase which is an enzyme that breaks down Ach
in NM junction)
A test dose of 2 mg of Tensilon is injected first.( IV push)
If no adverse events ( increased weakness; change in
heart rate or rhythm; nausea or abdominal cramps), the
remaining 8 mg is injected. ( slow IV push)
An abrupt improvement in symptoms lasting 5 -10
minutes is a positive test.

21. DIAGNOSIS…
Neostigmine methylsulfate ( Prostigmin) :
long acting anticholinesteerase has longer
effect on muscle strength ( 1-2 hrs) which
allows better analysis of its effect.
Used in children

22. DIAGNOSIS ( Cont..)
Electromyography: measure and document electric current
produced by skeletal muscles ( muscle action potential).
Small needle electrodes are inserted into muscles being
assessed for nerve innervations. A stimulator is placed over
peripheral nerve being tested.
Repetitive Nerve Stimulation (RNS): Progressively decreasing
amplitude; decrementing response of muscle action
potential
CT / MRI: thymus tumor, hyperplasia

23. Osserman’s Classification in MG
Asymptomatic
1 Ocular signs and symptoms
2 Mild generalised weakness
3 Moderate generalised weakness, bulbar dysfunction, or both
4 Severe generalised weakness, respiratory dysfunction, or both
The severity and progress of the disease is assessed using the Osserman classification

24. TREATMENT
Short Acting Anticholinesterase Compounds
Corticosteroids

25. TREATMENT
Cholinesterase Inhibitor
Pyridostigmine bromide (Mestinon)
Neostigmine bromide (Prostigmin)
Gastrointestinal complaints are common; loose
stools, nausea, vomiting, abdominal cramps, and
diarrhea

26. Corticosteroids
To reduce level of serum Ach receptor antibodies
Prednisone
Initial dose: 15 to 25 mg /d
Stepwise increase: 5 mg / d at 2 –3 day interval until reached by 50 mg / d
Maintained for 1 – 3 months
Gradually modified , alternate day for 2 –3 months,
Until a dose of 100mg is reached , alt day

27. Immunosuppressant Drugs
Azathioprine 2 –3 mg / kg B W
Cyclosporine 4 – 5 mg /Kg BW in 2 doses
Cyclophosphamide
Mycophenolate mofetil (MMF)

28. Immunomodulatory therapy
Intravenous Immune Globulin (IVIG)
(2 grams/kg infused over 2 to 5 days) I
Plasmapheresis to remove plasma protein
containing antibodies believed to cause M.G( plasma is
separated from formed elements of blood. Plasma is
discarded and packed RBCs are joined with albumin, N.S,
and electrolytes and returned back to client )

29. THYMECTOMY
The maximal favorable response generally
occurs 2 to 5 years after surgery.
The best responses to thymectomy are in
young people early in the course of their
disease, but improvement can occur even
after 30 years of symptoms.

31. COMPLICATIONS
Severe generalized and rapidly increasing
weakness, dysphagia or resp failure.
Myasthenia crisis due to undermedication.
Increased BP, HR, secretions, lacrimation. Absent cough
and swallow reflex.
Cholinergic crisis due to overdose. Weakness with
swallowing, chewing , speaking, breathing. Increased
secretions

32. NURSING MANAGEMENT

33. NURSING DIAGNOSIS
 Risk for ineffective breathing pattern related to the weakness of
the respiratory muscles.
 Impaired physical mobility related to voluntary muscle weakness.
 High risk for aspiration related to weakness of the bulbar
muscles.
 Impaired verbal communication related to the weakened speech
muscles.
 Fatigue related to muscle weakness.
 Sensory/perceptual alterations related to impaired vision.

34. Other relatednursingdiagnosis:
Altered nutrition less than body requirement
Altered family process.

36. Thank you !