A Case of Myopathic Dysphagia Secondary to Thyrotoxicosis

<h2>Abstract</h2><h3>Background/Objective</h3> Myopathic dysphagia is a rare manifestation of thyrotoxicosis. Bulbar muscle weakness may be isolated or may be associated with preceding proximal myopathy. <h3>Case description</h3> We describe a 70-year-old man with newly diagnosed Graves' disease who presented with acute dysphagia with both liquids and solids for 3 weeks, with free thyroxine (fT4) >73 pmol/L (reference range 8 to 16 pmol/L), free triiodothyronine (fT3) >40 pmol/L (reference range 3.5-6.0 pmol/L), thyroid stimulating hormone (TSH) <0.01 mIU/L (reference range 0.45-4.50 mIU/L), and TSH receptor antibody 28.6 IU/L (reference range 0.0-1.0 IU/L). This was associated with heat intolerance, palpitations, diarrhea, proximal weakness, and weight loss. A video fluoroscopy study confirmed moderate oropharyngeal dysphagia. Evaluation was done to exclude other causes including mechanical compression, neuromuscular causes and malignancy. The patient's dysphagia improved with Carbimazole doses of up to 30mg twice daily, and propranolol doses of up to 20mg thrice daily, titrated as thyrotoxicosis improved. He became euthyroid after 5 weeks of treatment, and had clinical improvement in swallowing by 8.5 weeks, improving from requiring nasogastric tube feeding to tolerating regular diet and thin fluids. <h3>Discussion</h3> We discuss differential diagnosis to consider and exclude, and the pathophysiology involved in myopathic dysphagia. Based on case reports in literature, patients responded well with high doses of thionamides, and beta blockers. <h3>Conclusion</h3> Our patient's dysphagia resolved rapidly with normalization of fT4 and fT3. It is important to render the patient euthyroid as soon as possible, to minimize risks of aspiration, pneumonia and other complications.