Overview
A medical case presentation discussed the assessment, differential diagnosis, and management of a patient with myasthenia gravis in crisis, with a focus on airway management, differentiating crises, and appropriate medication use.
Initial Assessment and Primary Survey
- Patient presented with one day of coughing, breathlessness, and mild pooling of secretions.
- Respiratory rate was 35/min; saturation 95% on 3L O2; heart rate 110 bpm; all peripheral pulses palpable.
- Two large-bore IV cannulas inserted; GCS 15/15; temperature 98.4°F; blood glucose 140 mg/dL.
- ABG: pH 7.35; pCO2 50; pO2 88; bicarb 24.
- ECG: sinus tachycardia; CBC: WBC 6000; CRP: 17.
History and Examination Findings
- Known case of myasthenia gravis for 5 years, on pyridostigmine 60mg BD.
- Recent history: two days of fever, productive cough, difficulty swallowing, ptosis, fluctuating muscle weakness, episodes of choking, and blurring of vision.
- CNS: Bilateral ptosis, normal limb power, facial weakness, sluggish gag reflex, weak neck flexion and shoulder shrug.
- Respiratory: Minimal right-sided collapse; CV: no murmurs; GI: normal bowel sounds.
Differential Diagnosis
- Primary diagnosis: Myasthenia crisis, likely precipitated by infection (suspected LRTA).
- Required differentiation from cholinergic crisis (overmedication).
- Other considerations: COPD, aspiration, chronic respiratory disease, other causes of acute bilateral paralysis (e.g., GBS, polio, spinal cord pathology, toxicity).
Diagnostic Approach
- Neostigmine test administered; improvement indicated myasthenic crisis.
- Differentiation based on symptoms and neostigmine response: myasthenic (under-medication) vs. cholinergic (over-medication) crises.
Airway and Management Strategies
- Airway: Decided based on secretion handling, gag and cough reflexes, not oxygen saturation alone.
- NIV considered for muscle fatigue if patient can maintain airway; intubation if condition worsens.
- In intubation, avoid depolarizing muscle relaxants (e.g., succinylcholine); use non-depolarizing agents at reduced dose.
- Monitor closely for prolonged effects and aspiration risk; use short-acting anesthetics in minimal necessary doses.
Medication and Procedural Considerations
- Neostigmine test requires atropine ready due to bradycardia risk; monitor baseline pulse.
- Short-term and long-term treatment plans include increasing pyridostigmine and steroids; consider thymectomy for thymoma.
Recommendations / Advice
- Carefully differentiate myasthenic from cholinergic crisis before adjusting medications.
- Intubation and anesthesia in myasthenia require dose adjustments and awareness of prolonged drug effects.
- Always have atropine available during neostigmine testing to manage potential bradycardia.
Questions / Follow-Ups
- Monitor for further signs of infection or aspiration.
- Serial reassessment for need for airway intervention or change in medication regime.