Terri Kueber, CRNA, MS

Myasthenia Gravis

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

Objectives

Myasthenia Gravis is an autoimmune neuromuscular

Consider a “Snowflake Disease”Cause is still unknownNo known cureHistory Incident and prevalence is increasing with 5-10

per 100,000 25,000 cases in USStill considered sporadicWomen versus menOften associated with other autoimmune disorders

Introduction

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

MGFA/Osserman Classification

Ocular Myasthenia GravisClassic General Myasthenia GravisTransient Neonatal Myasthenia GravisJuvenile Myasthenia GravisCongenital TypesDrug-induced (Pencillamine, NDMR,

aminoglycosides, procainamide)

Pathophysiologic Type

Presenting Symptoms

Bilateral or Unilateral Ptosis

DiplopiaHoarsenessAltered SpeechProblems chewingDysphagiaLimited Facial

Expressions

Endrophonium (tensilon) Chloride Test2.6-3.3 mg initial doseNeostigmine may be used in patients

who do not respond to tensilonAuto-antibodies in MG – receptor

binding antibodies are present in 80% of patients

Thymic hyperplasia is present in 70%

Diagnostic Procedures

Electromyography (EMG) TestingRepetitive Nerve Stimulation (RNS)

Single Fiber EMG (SFEMG)Ocular CoolingOther Testing

Diagnostic Procedures (continue)

Congenital Myasthenia Syndromes (not autoimmune)

Drug induced MGEaton-Lambert Syndrome (related to Small

cell carcinoma of the lung)Hyperthyroidism (increases MG symptoms)Graves diseaseBotulismOphthalmoplegiaIntracranial pathology

Differential Diagnosis

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

Factors that Worsen MG

Cholinesterase inhibitorPyridostigmine – most commonly usedNeostigmine – used less frequently

ThymectomyPlasmapheresisCorticoid Steroid TherapyImmunosuppressive therapy (azathioprine,

cyclosporine, etc.)Short-term Immunotherapy (IV

immunoglobulin)

Treatment for Myasthenia Gravis

Current health and symptomsPMH/PSHNMBA – MonitoringPost operative planPain controlInduction and Extubation criteria

Anesthetic Comsiderations

46 year old male diagnosis with MG in 6/2006Presenting symptoms: fatigue and weakness after

working out with intermittent dipopliaAt 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

Case Discussion #1

Height/Weight: 75”/95=4.7PFT’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)

Case Discussion (Continued)

Gave Pyridostigmine 90 mg preoperatively IVAdditional dose give at 1400 in recovery roomInduction included: slow induction no

neuromuscular blocking agentsTotal Agents included: Propofol 400mg

Fentanyl 300Morphine 4mgMidazolam 3 mg

Intubation with glidescope secondary to NIM’s tube placement.

What did we do??

Successfully extubated at end of case

Received pyridostigmine in recovery room

ICU overnight

Discharge next day.

Patient Outcome

63 year old maleDiagnosis between 12/05 and 2/06Schedule for Laparoscopic Nissen

FundoplicationMultiple drug allergiesEx-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 EsophagusPrevious surgery included: Brow lift,

Laparoscopic Cholecystectomy

Case Discussion #2

Previous anesthetic recordsSurgeons desire muscle relaxationWe did:

Propofol 350mgFentanyl 400 mcgMidazolam 2 mgZofran/DecadronEphedrine 15mgVasopressin 2 units

Patient’s was successfully extubated in OR and discharge home the next day

How did the case finish??

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Questions??

Thank you for your attention