Severe asthma associated with myasthenia gravis and upper airway obstruction.

An unusual association of asthma and myasthenia gravis (MG) complicated by tracheal stenosis is reported. The patient was a 35-year-old black woman with a history of severe asthma and rhinitis over 30 years. A respiratory tract infection triggered a life-threatening asthma attack whose treatment required orotracheal intubation and mechanical ventilatory support. A few weeks later, tracheal stenosis was diagnosed. Clinical manifestations of MG presented 3 years after her near-fatal asthma attack. Spirometry showed severe obstruction with no response after inhalation of 400 microg of albuterol. Baseline lung function parameters were forced vital capacity, 3.29 L (105% predicted); forced expiratory volume in 1 second (FEV1), 1.10 L (41% predicted); maximal midexpiratory flow rate, 0.81 L/min (26% predicted). FEV1 after administration of albuterol was 0.87 L (32% predicted). The patient's flow-volume loops showed flattened inspiratory and expiratory limbs, consistent with fixed extrathoracic airway obstruction. Chest computed tomography scans showed severe concentric reduction of the lumen of the upper thoracic trachea.