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Myasthenia Gravis

Myasthenia Gravis. Terri Kueber, CRNA, MS. Objectives . Explain the pathophysiology and classification of Myasthenia Gravis (MG) List the signs and symptoms and clinical manifestation Describe the various treatments available for Myasthenia Gravis

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Myasthenia Gravis

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  1. Myasthenia Gravis Terri Kueber, CRNA, MS

  2. Objectives • Explain the pathophysiology and classification of Myasthenia Gravis (MG) • List the signs and symptoms and clinical manifestation • Describe the various treatments available for Myasthenia Gravis • Discuss the anesthetic considerations for patients with Myasthenia Gravis

  3. Introduction • Myasthenia Gravis is an autoimmune neuromuscular • Consider a “Snowflake Disease” • Cause is still unknown • No known cure • History • Incident and prevalence is increasing with 5-10 per 100,000  25,000 cases in US • Still considered sporadic • Women versus men • Often associated with other autoimmune disorders

  4. MGFA/Osserman Classification • Class I: Ocular weakness, other muscle are normal • Class II: Mild weakness affecting other muscle • Class IIa: Muscles weakness affecting limbs and possibly oropharyngeal muscles • Class III: Moderate weakness/severe ocular weakness • Class IV: Severe weakness affecting limb muscle • Class V: Defined by intubation

  5. Pathophysiologic Type • Ocular Myasthenia Gravis • Classic General Myasthenia Gravis • Transient Neonatal Myasthenia Gravis • Juvenile Myasthenia Gravis • Congenital Types • Drug-induced (Pencillamine, NDMR, aminoglycosides, procainamide)

  6. Presenting Symptoms • Bilateral or Unilateral Ptosis • Diplopia • Hoarseness • Altered Speech • Problems chewing • Dysphagia • Limited Facial Expressions

  7. Diagnostic Procedures • Endrophonium (tensilon) Chloride Test • 2.6-3.3 mg initial dose Neostigmine may be used in patients who do not respond to tensilon • Auto-antibodies in MG – receptor binding antibodies are present in 80% of patients • Thymic hyperplasia is present in 70%

  8. Diagnostic Procedures (continue) • Electromyography (EMG) Testing • Repetitive Nerve Stimulation (RNS) • Single Fiber EMG (SFEMG) • Ocular Cooling • Other Testing

  9. Differential Diagnosis • Congenital Myasthenia Syndromes (not autoimmune) • Drug induced MG • Eaton-Lambert Syndrome (related to Small cell carcinoma of the lung) • Hyperthyroidism (increases MG symptoms) • Graves disease • Botulism • Ophthalmoplegia • Intracranial pathology

  10. Factors that Worsen MG • Fatigue or insufficient sleep • Stress, anxiety, illness • Overexertion, repetitive motion • Pain or depression • Low potassium or thyroid levels • Alcoholic beverages • Sudden fear, or extreme anger • Extreme temperatures • Humidity • Sunlight or bright lights • Hot foods or beverages • Medications (beta blockers, antibiotics, calcium blockers) • Chemicals such as household cleaner, insecticides, pet sprays, lawn chemicals

  11. Treatment for Myasthenia Gravis • Cholinesterase inhibitor • Pyridostigmine – most commonly used • Neostigmine – used less frequently • Thymectomy • Plasmapheresis • Corticoid Steroid Therapy • Immunosuppressive therapy (azathioprine, cyclosporine, etc.) • Short-term Immunotherapy (IV immunoglobulin)

  12. Anesthetic Comsiderations • Current health and symptoms • PMH/PSH • NMBA – Monitoring • Post operative plan • Pain control • Induction and Extubation criteria

  13. Case Discussion #1 • 46 year old male diagnosis with MG in 6/2006 • Presenting symptoms: fatigue and weakness after working out with intermittent dipoplia • At time of diagnosis weakness lead to respiratory failure leading ventilation and respiratory support x 3 days • Residual symptoms: weakness, pain and left ptosis • Refractory to medical support under went a thymectomy in October 2009

  14. Case Discussion (Continued) • Height/Weight: 75”/95=4.7 • PFT’s FVC=65%, FEV1/FVC=61% • Did not take his Pyridostigmine this am as he was instructed not to take it (not by anesthesia department)

  15. What did we do?? • Gave Pyridostigmine 90 mg preoperatively IV • Additional dose give at 1400 in recovery room • Induction included: slow induction no neuromuscular blocking agents Total Agents included: Propofol 400mg Fentanyl 300 Morphine 4mg Midazolam 3 mg Intubation with glidescope secondary to NIM’s tube placement.

  16. Patient Outcome • Successfully extubated at end of case • Received pyridostigmine in recovery room • ICU overnight • Discharge next day.

  17. Case Discussion #2 • 63 year old male • Diagnosis between 12/05 and 2/06 • Schedule for Laparoscopic Nissen Fundoplication • Multiple drug allergies • Ex-smoker (2 PPD x 30 years) • H/O: MG controlled with medications, HTN, diet controlled, AST – normal with EF 55-65% • Hiatal Hernia/Barrett’s Esophagus • Previous surgery included: Brow lift, Laparoscopic Cholecystectomy

  18. How did the case finish?? • Previous anesthetic records • Surgeons desire muscle relaxation • We did: • Propofol 350mg • Fentanyl 400 mcg • Midazolam 2 mg • Zofran/Decadron • Ephedrine 15mg • Vasopressin 2 units Patient’s was successfully extubated in OR and discharge home the next day

  19. Thank you for your attention Questions??

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