Myasthenia Gravis, multi-level spinal surgery

Gabrielle Morris

63yo male for removal of L3/4 hardware, L1/2 and L2/3 extreme lateral interbody fusion, posterior fixation T10 – pelvis. Multiple previous surgeries. Severe pain and dysfunction.

Background

  • Myasthenia gravis
    • Bulbar symptoms, swallowing difficulty, fatigues with mobilization
    • Relapse in 2019 when steroids weaned below 30mg/d pred.
    • No spirometry available
  • IHD
    • Angiogram 2019 – 40% mid-LAD stenosis (performed for atypical chest pain)
    • TTE – nil major abnormalities
  • HTN & Dyslipidaemia

Issues and discussion:

  • Should surgery proceed?
    • Reason for OT unclear during meeting.
    • High dose steroids -> concerns about bone quality and wound healing
  • Further myocardial perfusion imaging?
    • 40% mid LAD lesion previously.
    • Low exercise tolerance due to MG and spinal issues, unable to quantify
    • Will need to cease aspirin perioperatively
    • Unlikely to change management.
  • Cell salvage?
    • Nil obvious contraindications
    • With multi-level, long duration spinal surgery patient seems at high risk of significant bleeding.
  • Level of postop care?
    • Preoperative lung function studies required
    • Factors predictive of postop MG crisis and requirement for postop vent (UpToDate)
      • Vital capacity <2 
      • Duration of MG greater than 6yrs
      • Pyridostigmine dose > 750mg/d
      • History of chronic pulmonary disease
      • Preoperative bulbar symptoms
      • History of myasthenic crisis
      • Intraoperative blood loss > 1000ml
      • Serum anti-acetylcholine receptor antibody >100nmol/ml
      • More pronounced decremental response (18-20%) on low frequency repetitive nerve stimulation.

Plan

  • ICU level pending lung function studies
  • Discussed with surgeons.
    • If cell salvage is feasible/required – awaiting response
    • Indication for surgery and high-risk nature of patient – extensive discussions about this patient at spinal MDT. Two surgeons involved in case. Aware of the risks. Surgery felt to be necessary.
  • For discussion with cardiologist – requirement for stress imaging, and if postoperative ECG or troponin screening indicated.