Anti-MuSK-Positive Myasthenic Crisis in a 7-Year-Old Female

A seven-year-old African American female with anti-MuSK-positive Juvenile Myasthenia Gravis collapsed while at school from progressively worsening weakness and dyspnea. On initial emergency department presentation, she required 15 liters per minute of supplemental oxygen to maintain oxygen saturation above 92%. Initial pulmonary function tests and venous blood gas led to the decision to place her on noninvasive positive pressure ventilation (NPPV) with BiPAP in the emergency department. Due to worsening hypercarbia, she later required mechanical intubation in the PICU and underwent IVIG therapy followed by plasmapheresis in order to achieve a stable discharge from the hospital. A respiratory virus panel PCR was positive for influenza A, influenza B, and rhinovirus, likely precipitating the respiratory failure and myasthenic crisis in this seven-year-old patient. Given the rarity of this condition, this case report is to provide further education to the clinician managing severe, prepubertal Juvenile Myasthenia Gravis and myasthenic crisis.