Management Of Myasthenia Gravis- medicine cardiothoracic surgery

1. MANAGEMENT OF MYASTHENIA GRAVIS
OKOYE, C
CARDIOTHORACIC UNIT,
DEPT OF SURGERY, ABUTH
24/07/2020

2. OUTLINE
• Introduction
– Definition
– Epidemiology
– Pathophysiology
• Statement of Surgical Importance
• Classification
• Management
– History
– Examination
– Differential Diagnosis
– Investigations
– Treatment
• Prognosis
• Follow up
• Future Perspective
• Conclusion

3. Introduction
• The name myasthenia gravis (MG), which is
Latin and Greek in origin means ‘grave’ or
serious muscle weakness
• Available treatments can control symptoms and
often allow people to have a relatively high
quality of life.
• Most individuals with the condition have a
normal life expectancy.

4. Introduction
• Thymectomy for myasthenia gravis, first used by
Sauerbruchin 1912, was introduced again by
Blalock in 1939
• Became a widely used procedure in the last two
decades, when large series of cases proved this
treatment to be beneficial to patients with
myasthenia.

5. Definitions
• Myasthenia gravis is a chronic autoimmune
neuromuscular disease, that causes weakness in
the skeletal muscles worsens by periods of
activity and improves after periods of rest.

6. Definitions
• The thymus gland is a primary lymphoid organ
that is involved in development and maturity
of T-lymphocytes.
• It plays an important role in immunologic
development in early life and begin to involute
in adolescence.
• Thymic tumors are rare in children, most
common in middle-aged adult.

7. Epidemiology
• MG affects 14 per 100,000 people in the United
States and can affect any age group
• Of the 317patients studied in Poland, 252 were
women
• Female to male ratio being 3.9:1.
• Forty one percent of patients were aged 20-30
years
• Men – peak incidence 50's to 60’s
• Thymic tumors found in 15% of patients

8. Epidemiology
• Of patients with MG, 75% have thymic
disease, 85% have thymic hyperplasia, and
10–15% have thymoma

10. Statement of Surgical Importance
• The most common paraneoplastic syndrome
associated with thymoma is myasthenia gravis
(MG).
• Findings from a recent NINDS-supported study
yielded conclusive evidence about the benefits of
surgery for even individuals without thymoma, a
subject that had been debated for decades
• This presentation would attempt to highlight the
association of thymoma with MG and associated
clinical and therapeutic issues.

11. Osserman and Genkins Classification
Pediatric myasthenia gravis
A. Neonatal group (1%)
– Infants born of myasthenic mothers
– Self-limited, lasting no more than 6 weeks after birth
– Probably caused by tr
B. Juvenile group (9%)
– Nonmyasthenic mother
– Onset any time from birth to puberty
– Tends to be permanent
– Familial involvement
– Myasthenia gravis disability classified as in adult
myasthenia gravis

12. Osserman and Genkins Classification
• III. Adult myasthenia gravis
Group 1: Ocular (15% to 20%)
– Limited to ocular muscles
– 40% ultimately develop clinically generalized disease
– Electromyographic results may be positive in
peripheral muscles
• Group 2A: Mild generalized disease (30%)
– Involves cranial, limb, and truncal muscles
– Respiratory musculature spared
– Good response to anticholinesterase drugs
– Low mortality

13. Osserman and Genkins Classification
• Group 2B: Moderately severe generalized
disease (20%)
– Significant diplopia and ptosis
– Bulbar muscle involvement: dysarthria, dysphagia,
feeding difficulty
– Limb weakness
– Exercise intolerance

14. Osserman and Genkins Classification
• Group 3: Acute fulminating disease (11%)
– Abrupt onset
– Most severe symptoms appear by 6 months
– Early respiratory muscle involvement
– Severe bulbar, limb, and truncal weakness
– Poor response to anticholinesterases
– Frequent crises
– High mortality
– Thymoma relatively frequent

15. Osserman and Genkins Classification
• Group 4: Late severe disease (9%)
– Progression from milder disease after 2
years
– High incidence of thymoma
– Relatively poor prognosis

16. Classification based on muscle affected
1: Eye muscle weakness (EMW)
2: EMW and other mild muscle weakness
Predominantly limb or axial muscles
Predominantly bulbar or respiratory muscles
3: EMW and other moderate weakness
Predominantly limb or axial muscles
Predominantly bulbar or respiratory muscles
4: EMW and other severe weakness
Predominantly limb or axial muscles
Predominantly bulbar or respiratory muscles
5: Intubation needed to maintain airway

17. Management
• Resuscitation
• Sometimes the severe weakness of
myasthenia gravis may cause respiratory
failure, which requires immediate emergency
medical care

18. Management
History
• The onset of the disorder may be sudden, and
symptoms often are not immediately recognized
as myasthenia gravis.
• Painless
• Weakness of the eye muscles (called ocular
myasthenia)
• Drooping of one or both eyelids (ptosis)
• Blurred or double vision (diplopia)

19. Management
History
• Changes in facial expression
• Difficulty chewing
• Difficulty swallowing
• Difficulty breathing
• Impaired speech (dysarthria)
• Weakness in the arms, hands, fingers, legs,
and neck.

20. Management
History
• Symptoms may worsen with exposure to
extreme heat or emotional stress, infection,
systemic illness, pregnancy, the menstrual
cycle, or drugs that affect neuromuscular
transmission
• Patients may report that they plan activities
for early in the day when their strength is at
its peak.

21. Management
On Examination
• Do a general examination
• Findings may not be apparent unless muscle
weakness is provoked by repetitive or
sustained use of the muscles involved.
• Recognize a patient in whom respiratory
failure is imminent.

22. Management
On Examination
• Weakness of eyelid closure is seen in most
patients with MG and should be specifically
tested
• Patients are unable to whistle, suck through a
straw, or blow up a balloon
• Sensory examination and deep tendon
reflexes are normal.

23. Management
On Examination
• Counting aloud (1 to 50): Enhances dysarthria
(nasal, lingual, or labial) and results in
dyspnea.
• Patient may sound relatively clear on speaking
initially but will become increasingly
dysarthric to the point of becoming
unintelligible.

24. Myasthenic Crisis
Requires immediate assistance
• Shortness of breath
• Extreme muscle weakness
• General fatigueablility
• Respiratory muscle paralysis
• Requires ventilatory supports

25. MG in Pregnancy
• Many mothers get worse 1st trimester and
better 2nd and 3rd trimester.
• Up to 10% of infants born to mothers with MG
will have Transient Neonatal Myasthenia.
– Weak cry, poor muscle tone, difficulty breathing
etc…

26. Differential Diagnosis
• Lambert-Eaton Myasthenic Syndrome (LEMS)
• Multiple Sclerosis
• Brainstem Gliomas
• Chronic Myelogenous Leukemia (CML)
• Congenital Myasthenic Syndrome
• Dermatomyositis
• Diphtheria
• Graves Disease
• Guillain-Barre Syndrome

27. Differential Diagnosis
• Tolosa-Hunt Syndrome
• Thyroid Ophthalmopathy
• Myocardial Infarction
• Organophosphate Toxicity
• Polymyositis
• Pulmonary Embolism (PE)
• Tetrodotoxin Toxicity
• Amyotrophic Lateral Sclerosis
• Basilar Artery Thrombosis
• Botulism

28. Management
Investigations;
• Electrodiagnostic studies (repetitive nerve
stimulation and single-fiber
electromyography)
• Tensilon test
• CXR may identify an anterior mediastinal mass
• Chest CT to identify or rule out thymoma or
thymic enlargement

29. Management
Investigations
• In strictly ocular MG, MRI of the brain and
orbit is helpful to evaluate for mass lesions
compressing the cranial nerves or a brainstem
lesion that may masquerade as ocular MG
• Blood tests
– Tests for specific antibodies
– TFT- RF- ANA

30. Management
Treatment
• Multidisciplinary and Multimodal
• Medical and Surgical

31. Management
• Treatment decisions are based on predicted
response to a specific form of therapy
• The treatment goals must be individualised
according to severity of the disease, the
patient’s age and sex, and the degree of
functional impairment

32. Management
Cholinesterase inhibitors
• Mestinon (pyridostigmine bromide 30-60mg
6-8hrly
• Neostigmine 7.5-15mg 6-8hrly

33. Management
Steroids
• Prednisolone 60-80mg/day
• Marked or complete relief of symptoms in
75% of patients

34. Management
Immunosuppressants
• Azathioprine (2-3 mg/kg/day)
• Cyclosporine
• Mycophenolate mofetil
• Rituximab

35. Management
Plasmapheresis and Intravenous
Immunoglobulin (IVIg)
•
Administered during myasthenic
exacerbations to produce short-term clinical
improvement
• Plasmapheresis rapidly lowers AChR antibody
titers

36. Management
Surgical
Indications for surgery
• Patients with thymoma
• Patients aged 10-55 years without thymoma but
who have generalized MG.
• A rapid increase of myasthenic symptoms
• Failure of medical management
• Advanced myasthenia with bulbar and respira-
tory symptoms.

37. Management
Surgical
• Thymectomy has been proposed as a first-line
therapy in most patients with generalized
myasthenia.
• Remission rate increases with time: at 7-10
years after surgery, it reaches 40-60% in all
categories of patients except those with
thymoma.

38. Management
Surgical
• In the absence of a thymoma, 85% of patients
experience improvement, and 35% of these
patients achieve drug-free remission.
• In a study by Nieto et al, the rate of remission
in the presence of thymic hyperplasia was
42% compared to 18% in patients with
thymoma

39. Management
Surgical
• Over the years, many different techniques have been
employed to perform thymectomy.
• Although it is generally believed that complete removal of
thymic tissue is better; this is not an established fact.
• There is no consensus as to whether one technique is
superior to another in achieving benefit or minimizing risks.
• The Myasthenia Gravis Foundation of America (MGFA) has
proposed a classification scheme for thymectomy, which is
primarily based on techniques described in various
published reports.

40. Management
Surgical
The MGFA thymectomy classification is as follows:
• T-1 transcervical thymectomy – Basic; Extended
• T-2 videoscopic thymectomy – Classic VATS or
VATET
• T-3 transsternal thymectomy – Standard;
Extended
• T-4 transcervical and transsternal thymectomy

41. Prognosis
• Disease course is highly variable; ranging from
remission to death.
• Ocular Myasthenia has the best prognosis.
• Thymectomy results in complete remission of
the disease in a number of patients.
• Mortality rate is 2-3%

42. Follow Up
• Educate patients about the fluctuating nature
of weakness and exercise-induced fatigability.
• Follow-up by specialists is necessary to secure
optimal treatment regarding effect on muscle
strength, as well as to avoid unnecessary side
effects.
• Rehabilitation

43. Future Perspective
• Until an antigen-specific MG treatment is
available, it remains a challenge to evaluate
new and promising immunoactive drugs for
MG.
• The aim should be to suppress the anti-AChR,
anti-MuSK immune response in MG patients
without influencing the rest of the immune
system

44. Conclusion
• The management of MG involves a
multidisciplinary and multimodal approach
• From establishing diagnosis, deciding the
therapeutic strategy and evaluating the
prognosis.
• With advances in medical science, new surgical
techniques and drugs, there is a remarkable
improvement in the management of MG.

45. •THANK YOU

46. References
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