How to manage dysphagia in a patient with myasthenia gravis?

Management of Dysphagia in Myasthenia Gravis

Dysphagia in myasthenia gravis requires prompt evaluation with pulmonary function assessment and treatment with pyridostigmine as first-line therapy, followed by corticosteroids if needed, while avoiding medications that can worsen neuromuscular transmission. 1, 2

Initial Assessment and Evaluation

• Perform pulmonary function assessment with negative inspiratory force (NIF) and vital capacity (VC) measurements to evaluate respiratory function and risk of aspiration 2
• Assess for silent aspiration, which occurs in approximately 20% of myasthenic patients with dysphagia 3, 4
• Check acetylcholine receptor (AChR) antibodies; if negative, test for muscle-specific kinase (MuSK) and lipoprotein-related protein 4 (LRP4) antibodies 2
• Consider videofluoroscopic swallow study to characterize the dysphagia, as abnormalities can occur in oral, pharyngeal, and oral preparatory phases 4

Pharmacological Management

• Initiate pyridostigmine bromide as first-line treatment, starting at 30 mg orally three times a day and gradually increasing to maximum of 120 mg orally four times a day 1
• Be aware that approximately 50% of patients with myasthenia-related strabismus show minimal response to pyridostigmine, suggesting similar response rates may occur with bulbar symptoms 1
• Add corticosteroids (prednisone 1-1.5 mg/kg/day) if inadequate response to pyridostigmine, as 66-85% of patients show positive response to this treatment 1, 2
• Monitor for cardiac side effects of pyridostigmine, including bradyarrhythmias, which can be managed with hyoscyamine if they occur 5

Medications to Avoid

• Strictly avoid medications that can worsen myasthenic symptoms: beta-blockers, IV magnesium, fluoroquinolones, aminoglycosides, and macrolide antibiotics 6, 2
• If antibiotics are necessary, consult neurology for appropriate antibiotic selection 6
• Exercise caution with anesthetic agents if procedures are required, as depolarizing agents like suxamethonium are contraindicated 6

Nutritional Management Strategies

• For mild dysphagia: implement dietary modifications with thickened liquids and soft foods 7
• Instruct patients to eat slowly, chew thoroughly (≥15 chews per bite), and avoid dry foods that may exacerbate dysphagia 1
• For moderate to severe dysphagia: consider enteral nutrition via nasogastric tube or percutaneous endoscopic gastrostomy (PEG) if oral intake remains inadequate 7
• In refractory cases with significant weight loss, PEG placement may be necessary to prevent malnutrition 7

Management of Myasthenic Crisis with Severe Dysphagia

• Hospitalize patients with severe dysphagia and respiratory compromise for ICU-level monitoring 2
• Administer high-dose corticosteroids: methylprednisolone 1-2 mg/kg/day IV or prednisone 1-1.5 mg/kg/day orally 2
• Consider rapid immunomodulation with either:
  • Plasmapheresis (5 sessions over 5 days) OR
  • IVIG (2 g/kg total dose over 5 days at 0.4 g/kg/day) 2
• Monitor respiratory function closely with frequent NIF and VC measurements 2

Clinical Prediction of Aspiration Risk

• Simple bedside tools can help predict aspiration risk in myasthenic patients 3
• Key predictive factors include:
  • Patient-reported swallowing difficulties on questionnaires
  • Bulbar symptoms on neurological examination
  • Quantitative myasthenia gravis (QMG) bulbar subset score 3
• Speech pathology assessment is highly sensitive but less specific for predicting aspiration 3

Long-term Management Considerations

• For patients with refractory disease, immunosuppressive therapy with azathioprine or efgartigimod alfa-fcab (FDA approved for anti-acetylcholine receptor positive patients) may be considered 1
• Thymectomy may be indicated in some cases, particularly in the presence of thymoma, and can substantially reduce symptoms 1
• Consider surgical intervention for strabismus only after 2-3 years of treatment when disease has stabilized 1