That’s Pretty Hard to Swallow: A Rare Case of Dysphagia Due to Myasthenia Gravis

Abstract

Introduction: An 89-year-old woman with GERD and hypothyroidism presented with a 7-month history of dysphagia and odynophagia to both solids and liquids. She was admitted 1 month prior to this admission for similar symptoms and underwent an EGD, which revealed a hiatal hernia. Despite compliance with omeprazole 40 mg daily, she returned to the emergency room with worsening symptoms. She denied abdominal pain, nausea, vomiting, diarrhea, constipation, dark stools, blood per rectum, or jaundice. Physical exam revealed an elongated face with bitemporal wasting, bilateral partial ptosis, and dysarthria. Motor strength was 4/5 in both upper and lower extremities. The abdominal exam was benign. Evaluation for gastrointestinal causes of dysphagia included a video esophagram showing decreased peristalsis and a repeat EGD revealing no resistance to a balloon dilator nor evidence of stricture, rings, or masses. Due to negative GI imaging, evaluation for neurological causes of dysphagia was completed. This included MRI brain and MRA of the head & neck which were negative for infarction or stenosis of vessels. CT scan of the neck was negative for right recurrent laryngeal nerve paralysis. By hospital admission day 4, she was intubated for inability to swallow her secretions and given an NG tube for feeds. Labs revealed elevated aldolase level of 7.9. Due to suspicion for neuromuscular causes of dysphagia, electromyography was completed, revealing a neuromuscular junction abnormality. Voltage-gated Ca-channel antigen and anti-MuSK antibody were negative while acetylcholine receptor-binding antibody level was 5.63 (high), acetylcholine receptor-modulating antibody level was 30 (high), and acetylcholine receptor-blocking antibody was 83 (high), thus confirming the diagnosis of myasthenia gravis as the cause of dysphagia. Repetitive nerve stimulation showed a decremental response further solidifying the diagnosis. CT scan of the chest did not reveal presence of a thymoma. She was started on IV immunoglobulins for 5 days, prednisone 50 mg daily, and pyridostigmine 60 mg three times a day with improvement in her muscle weakness, ptosis, and dysphagia. Dysphagia as the primary presenting symptom of myasthenia gravis is very rare and has only been reported in 6-15% of cases of myasthenia gravis. Myasthenia gravis is more commonly reported as a paraneoplastic phenomenon associated with a thymoma/thymic tumor, which was absent in our case. Late-onset myasthenia gravis is more common in men and is often acetylcholine-receptor antibody negative. The age of onset along with the gender and antibody profile of our patient makes this case very unique. Our case truly increases awareness of nongastrointestinal causes of dysphagia. Disclosure - 1. Dr. Kumkum Patel--no financial relationships. 2. Dr. Jacqueline Forman--no financial relationships. 3. Dr. Bhawna Halwan--no financial relationships. 3. Dr. James Grendell-Consultant: NPS Pharmaceuticals Advisory Board.