Thymectomy Perioperative Management of Myasthenia Gravis

1. A D E W I J A Y A , M D – A U G U S T 2 0 2 2
Thymectomy Perioperative Management
of Myasthenia Gravis

2. Thymic Masses
 Originate from thymus gland with indolent growth
behavior
 Benign tumor but may exhibit malignant behavior
 Most common mediastinum tumor (20-25%) and 50
% of anterior mediastinum tumor
 Thymic carcinoma represents 15%–20% of all thymic
masses  malignant
 The relationship of Myasthenia Gravis (MG) to a
thymic mass was first made by Weigert in 1901
Ahmed, A. B., Al Salmi, I., Al Rahbi, F., Al Farsi, A., & Hannawi, S. (2021). The role of thymectomy in myasthenia gravis: A programmatic approach to thymectomy and
perioperative management of myasthenia gravis. Asian Journal of Surgery, 44(6), 819-828.

3. Myasthenia Gravis (MG)
 An autoimmune disorder of neuromuscular junction
 Antibodies against the acetylcholine receptors
characterized by fatigable weakness of skeletal
muscles.
 Present in 30% of patients with thymic masses
 10–15% of patients with MG develop thymic masses
Ahmed, A. B., Al Salmi, I., Al Rahbi, F., Al Farsi, A., & Hannawi, S. (2021). The role of thymectomy in myasthenia gravis: A programmatic approach to thymectomy and
perioperative management of myasthenia gravis. Asian Journal of Surgery, 44(6), 819-828.
Hayashida N, Kawara T, Akasu K, Kai E, Kosuga T, Chihara S, et al. Coronary artery bypass surgery in a patient with myasthenia gravis. Kurume Med J 2000;47:173-5.

4. Thymectomy
 The role of Thymectomy in MG began in 1912 when
Sauerbrach et al noted significant improvement in a
myasthenic patient after removal of thymic mass
 Perioperative management
Ahmed, A. B., Al Salmi, I., Al Rahbi, F., Al Farsi, A., & Hannawi, S. (2021). The role of thymectomy in myasthenia gravis: A programmatic approach to thymectomy and
perioperative management of myasthenia gravis. Asian Journal of Surgery, 44(6), 819-828.

5. Thymectomy Indications
 All MG with thymoma
 In the absence of thymoma, thymectomy is generally
thought to be beneficial to generalize MG and AChR
antibodies-positive patients
 Prevalence of remission after thymectomy was higher in
patients with preoperative mild MG disease
 Elderly individuals may not respond well to thymectomy
because of high thymic involution incidence and that
risks of thymectomy may be serious than potential
benefits. For this reason, most centers do not perform
thymectomy for patients older than 60 years
 Generalized MG has been reported to have a double-
seronegative MG as an indication for thymectomy
Aydin Y, Ulas AB, Mutlu V, Colak A, Eroglu A. Thymectomy in Myasthenia Gravis. Eurasian J Med. 2017 Feb;49(1):48-52. doi: 10.5152/eurasianjmed.2017.17009. PMID:
28416933; PMCID: PMC5389494.

6. Thymectomy Indications
 Generalized MG has been reported to have a double-
seronegative MG as an indication for thymectomy
 Present findings in the literature do not support the
benefit of thymectomy in MuSK antibody-associated
MG
 Thymectomy should be postponed until post-
pregnancy
 Ocular MG; no benefit of thymectomy proven
Aydin Y, Ulas AB, Mutlu V, Colak A, Eroglu A. Thymectomy in Myasthenia Gravis. Eurasian J Med. 2017 Feb;49(1):48-52. doi: 10.5152/eurasianjmed.2017.17009. PMID:
28416933; PMCID: PMC5389494.

7. Preoperative Management
 Contrast-enhanced thorax computerized tomography must be
performed
 Interdisciplinary approach
 Should be performed during the stable phase of the disease, when
the patient requires minimal immunomodulatory medication
 Should be scheduled as early as possible in the day, when the
patient is strongest
 Preoperative lung function assessment
 Intravenous immunoglobulin or plasmapheresis preoperatively
before thymectomy or other surgery
 Continuation of regular anticholinesterase treatment until surgery
and even giving the last drug dose in morning of operation day is
very important
Nagre, A. S., Kabade, A., & Chaudhari, M. (2022). Perioperative management of myasthenia gravis patient for off pump coronary artery
bypass surgery and thymectomy. Annals of Cardiac Anaesthesia, 25(2), 236.
Aydin Y, Ulas AB, Mutlu V, Colak A, Eroglu A. Thymectomy in Myasthenia Gravis. Eurasian J Med. 2017 Feb;49(1):48-52. doi: 10.5152/eurasianjmed.2017.17009. PMID:
28416933; PMCID: PMC5389494.

8. Postoperative Mechanical Ventilation
Predictor Parameter
 Duration of the disease >6 years
 Presence of any lung disease
 Past history of myasthenic crisis
 Pulmonary function terst reporting the vital capacity
<2.9 L
 The requirement of the dosage of pyridostigmine
>750 mg/day
Nagre, A. S., Kabade, A., & Chaudhari, M. (2022). Perioperative management of myasthenia gravis patient for off pump coronary artery
bypass surgery and thymectomy. Annals of Cardiac Anaesthesia, 25(2), 236.

9. General Anesthesia Considerations
 The main goal of anesthetic management is to prevent
prolonged effects of drugs on respiratory and bulbar
muscles and allow rapid recovery at the end of surgery
 Use of short-acting sedatives, hypnotics, and anesthetic
agents to minimize respiratory depression on emergence
from anesthesia
 Smallest effective dose
 Neuromuscular monitoring
 Treatment with anticholinesterase medication
(pyridostigmine) may prolong the effect of
succinylcholine
Nagre, A. S., Kabade, A., & Chaudhari, M. (2022). Perioperative management of myasthenia gravis patient for off pump coronary artery
bypass surgery and thymectomy. Annals of Cardiac Anaesthesia, 25(2), 236.

10. General Anesthesia Considerations
 MG patients are extremely sensitive to nondepolarizing NMBAs
(rocuronium, vecuronium, cisatracurium).
 Even small doses and residual drug effect may result in respiratory
distress or loss of airway protection after emergence from
anesthesia.
 They should be administered in incremental and minimal doses
titrated to effect.
 The neuromuscular monitoring is essential while administering
general anesthesia to avoid the prolonged neuromuscular blockade
in them
 They are more sensitive to the relaxant effect of volatile anesthetics
 Sugammadex has been used safely for the reversal of steroidal
NMBAs such as vecuronium and rocuronium with no issues of
cholinergic crisis
Nagre, A. S., Kabade, A., & Chaudhari, M. (2022). Perioperative management of myasthenia gravis patient for off pump coronary artery
bypass surgery and thymectomy. Annals of Cardiac Anaesthesia, 25(2), 236.

11. Postoperative Follow Up
 Close observation
 To assess respiratory status, vital capacity measurements
can be done in every 6 hours by inspiratory-expiratory
pressures
 Aggressive bronchopulmonary cleaning precautions
should be taken
 Starting anticholinesterase agents early in the
postoperative period will reduce oral and tracheal
secretion problems and possibility of cholinergic crisis
 If the patients’ breathing worsens, plasmapheresis
should be considered immediately
Aydin Y, Ulas AB, Mutlu V, Colak A, Eroglu A. Thymectomy in Myasthenia Gravis. Eurasian J Med. 2017 Feb;49(1):48-52. doi: 10.5152/eurasianjmed.2017.17009. PMID:
28416933; PMCID: PMC5389494.

12. Summary
 MG – thymic masses
 Thymectomy is one of the MG treatment option in
selected cases
 Perioperative management – interdisciplinary

13. THANK YOU