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myasthenia%20gravis
MYASTHENIA GRAVIS
Myasthenia gravis is an autoimmune neurological disorder caused by autoantibodies against the acetylcholine receptor or against a receptor-associated protein, muscle-specific tyrosine kinase (MuSK-Ab).
The autoimmune attack at the muscle endplate leads to failure of neuromuscular transmission and eventually muscle weakness.
In the active phase of the disease, symptoms typically fluctuates and then become severe; myasthenic crisis occur in this phase.
In the stable/inactive phase, symptoms are stable but still persist; it usually worsen attributable to infection, fatigue, tapering of medications or other identifiable factors.
In the burnt-out phase, remission may occur wherein patients are on immunotherapy and symptom-free, or may even be off medications.
In 15-20 years, if the symptoms left untreated, patient's weakness becomes fixed wherein the most severely affected muscles become atrophic.

Surgical Intervention

Thymectomy

  • No consensus is in place on which surgical method is first line
  • Based on a study, more severe cases of myasthenia gravis may benefit from thymectomy compared to patients with mild myasthenia gravis
  • It is advisable that the patient be stabilized with immunotherapy before undergoing thymectomy to reduce perioperative morbidity & mortality
  • Patients with acetylcholine receptor antibody-positive early-onset generalized myasthenia gravis with insufficient response to pyridostigmine therapy are candidates for thymectomy
  • Video-assisted thoracoscopic surgery (VATS) may be considered in preference to the transsternal approach
  • Many papers demonstrate superior results of VATS in terms of hospital stay, operative blood loss & patient satisfaction compared to the transsternal approach

Presence of Thymoma

  • If patient has a thymoma it is highly recommended that the patient undergo early total thymectomy to prevent local tumor spread (although most tumors are benign)
    • Tumor & adherent structures should be completely removed
    • Chest cavity should be inspected for tumor implants
  • 66% of patients with myasthenia gravis  & nonmalignant thymoma were found to be symptom-free at 6 months-7 years after thymectomy & treatment with Prednisolone &/or Azathioprine therapy

Non-Thymomatous Autoimmune Myasthenia Gravis

  • Thymectomy in the absence of tumor offers possibility of long-term benefit for those with generalized myasthenia gravis & anti-AChR antibodies
    • It may increase the probability of improvement or drug-free remission
  • Studies showing improvement have conflicting differences in baseline characteristics of prognostic factors & confounding variables (eg age, severity of myasthenia gravis)
    • Regardless, most studies have found improvement or myasthenia gravis remission in patients undergoing thymectomy
    • Improvement is slow & may take months-years

Ophthalmic Surgery

  • For correction of ptosis &/or diplopia
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