Myasthenia gravis is an autoimmune disease that causes muscle weakness. It is caused by antibodies that block signals from nerves to muscles. The main symptoms are drooping eyelids, blurred vision, difficulty speaking and swallowing, and weakness in the limbs. Diagnosis involves tests like tensilon tests, EMGs, and checking for antibodies against acetylcholine receptors or related proteins. Treatment focuses on medications to enhance nerve signaling, immunosuppressants, and sometimes surgery to remove the thymus gland. Crises can occur where weakness suddenly worsens and ventilator support may be needed.

1. MYASTHENIA GRAVIS
By: dr. SURESH KUMAR (HO)
Medicine dept.
Lyari general hospital

2. INTRODUCTION:
• Myasthenia = muscular weakness/ fatigability
• Gravis = serious, so literally, serious muscular weakness.
• It is an autoimmune disease of NMJ ( neuromuscular
junction) causes muscular weakness specialy involves,
occular, facial, bulbar muscles.
• Incidance rate is 2 to 4 per million of patients in tertiary
care hospitals of karachi ( a/c to an article published in
2016) .

3. PATHOPHYSIOLOGY:

4. Pathophysiology continues...
• Autoimmune
• Type || hypersenstivity
• Most commonly caused by antibodies to acetylcholine
receptor ( 80%) , results blockage of neuromuscluar
transmission and complement-mediated inflamatory
response reduces the number AchR and damages end
plate.
• Autoantibodies to muscle specific-kinase(MuSK) also
produce similar clinical picture.
• 65% associated with thymic hyperplasia, 15% thymoma

5. CLINICAL FEATURES:
• Myasthenia gravis usaully presensts between the age of
15 - 50 years with female preponderance.
• In older patients , males are more commonly affected.
• It tends to run a relapsing and remitting course.
• The most evident symptoms is fatigable muscle
weakness.
• Movemnet is initially strong but rapidly weakens as
muscle use continues, worsening of symptoms towards
the ends of the day or following exercise is characteristic

6. Clinical features
continues......
• The first symptoms are usauly
intermittent ptosis or diplopia , but
weakness of chewing, swallowing ,
speaking or limb movemnet also occur.
• Any limb muscle may be affected, most
commonly those of the shoulder girldle ;
the patient is unable to undertake tasks
above shoulder level , such combing hair,
without frequent rest.

7. Clinical features
continues...
• Respiratory muscles may be involved
and respiratory failure is an avoidale
cause of death .

9. INVESTIGATIONS:
1. TENSILON TEST: it is NOT routinely used. It involves
intravenous injection of edrophonium bromide ( anti-
cholinesterase). It results in rapid imrovemnt of
symptoms within 30 seconds. With cover of atropine.
2. EMG and NCS: mostly normal.
3. RNS: repeated nerve stimulation; it shows characteristic
decremental response ; greater then 10% decrement in
compound muscle action potential CMAP
4. SFEMG: single fiber EMG, most specific

10. Investigations continues.....
5. Serum AchR antibodies test: 80%
6. Serum AntiMuSK antibodies test: in AchRA- negative
with bulbar involvemnet.
7. Thoracic CT: to exclude thymoma,
8. Myasthenic patient are at greater risk of associated
organ- specific autoimmune disease. So should screened
for associated autoimmune disorder, particularly thyroid
disease.

11. MANAGEMENT:
• The goal of treatment are to maximise.
• the activity of acetylcholine at remaining receptors in nmj
• Limit the immunological attack on motor end plate.
1. Anticholiestrase agents: these agents are as best
initial therapy. Prolong the duration of action of
acetylcholine at nmj. Most commonly used agent is
pyridostigmine. Its adverse effects are diarrhoea, colic, .
2. Immunological treatments:
• Acute ( emergency ) treatment: i/v immune globin IVIG

12. Treatment continued....
Reduces production of antibodies and rapidly reduces
weakness.
• OR plasma exchange ( plasmapharesis): it removes
antibody from the blood may produce marked
improvemnet this usauly brief, so normally reserved for
myasthenic crisis

13. Treatment continued....
• Long term treatment:
1. Corticosteroid treatment ( prednisolone) :
2. Immunosuppresants treatment:
• Azithioprine
• Cyclophosphamide
• 3.Thymectomy:
• Should considered in,
• Thymoma
• antibody +ve patient below 45 yrs plus
• Symtpoms not confined to extrocular muscles.

15. Myasthenic crisis:
• It refer to exacerbation of myasthenia
• It presents with severe weakness, with potentially lethal
complication of respiratory failure and aspiration.
• Treatment:
1. Immunosupression with glucocorticoids.
2. IVIG or. Plasmapharesis.

16. Cholinergic crises:
• It is due over dosage of anti-cholinestrase drugs,
• It presents with muscle fasciculation, paralysis, pallor,
sweating, excessive salivation and constricted pupil.
• Treatment:
1. Withdrawl of anti-cholinestrase drugs.
2. Endotracheal intubation if respiratory paralysis.