Myasthenia gravis masquerading as dysphagia: unveiled by magnesium infusion

Myasthenia gravis (MG) is a neuromuscular disorder that typically affects the ocular, bulbar, neck, proximal limbs and respiratory muscles. Dysphagia can occasionally be the only presenting symptom leading to extensive but ultimately futile gastrointestinal workup. Delay in diagnosis and use of certain pharmacological agents in the interim can lead to a myasthenic crisis, which though diagnostic is life threatening. We document a case of dysphagia as the only symptom of myasthenia, diagnosed after a magnesium infusion precipitated myasthenic crisis. A 70-year-old Caucasian woman who had had progressive dysphagia for 2 years, for which multiple oesophageal dilations were performed. During a hosptalisation for further gastrointestinal workup, she went into myasthenic crisis (respiratory failure) after receiving magnesium replacement. She required ventilatory support and received five plasma exchange (PLEX) treatments after myasthenia was confirmed by the detection of high antiacetylcholine receptor antibody. Though her symptoms improved, she had a prolonged hospital stay (25 days) and required 18 days of mechanical ventilation. This underscores the morbidity associated with a delay in diagnosis of this condition. This case report suggests that neuromuscular causes should be considered early in elderly patients presenting with dysphagia. Timely diagnosis, initiation of management and avoidance of drugs that affect neuromuscular transmission may help reduce the morbidity and mortality associated with myasthenic crisis.