Putman M T, Wise R A
Department of Pulmonary and Critical Care Medicine, Johns Hopkins Hospital, Baltimore, USA.
Chest. 1996 Feb;109(2):400-4. doi: 10.1378/chest.109.2.400.
Respiratory impairment in myasthenia gravis is usually attributed to weakness of the diaphragm and thoracic chest wall muscles, and is rarely attributed to upper airway obstruction. Myasthenia gravis is characterized by weakness of the striated muscles and usually affects those innervated by the bulbar cranial nerves. Weakness of these bulbar and upper airway muscles can lead to upper airway obstruction. To our knowledge, there are only five case reports in the literature associating upper airway obstruction with myasthenia gravis. Therefore, we attempted to further define its occurrence in myasthenia gravis patients by reviewing their flow volume loops. We present a case of upper airway obstruction causing respiratory symptoms in a myasthenia gravis patient. We then surveyed a total of 61 patients with myasthenia gravis who were tested in our pulmonary function laboratory between February 1990 and August 1993. Of these 61 patients, 12 had flow volume loops and 7 of these 12 disclosed a pattern of extrathoracic upper airway obstruction. The FVC was 80% or more in five of seven patients. Our data suggest that upper airway obstruction is much more common in patients with myasthenia gravis than previously recognized. In conclusion, we recommend the performance of flow volume loops in patients with myasthenia gravis to evaluate their respiratory impairment.
重症肌无力患者的呼吸功能障碍通常归因于膈肌和胸壁肌肉无力，很少归因于上呼吸道梗阻。重症肌无力的特点是横纹肌无力，通常影响由延髓颅神经支配的肌肉。这些延髓和上呼吸道肌肉无力可导致上呼吸道梗阻。据我们所知，文献中仅有5例关于上呼吸道梗阻与重症肌无力相关的病例报告。因此，我们试图通过回顾重症肌无力患者的流量容积环来进一步明确其在上呼吸道梗阻中的发生率。我们报告1例重症肌无力患者因上呼吸道梗阻导致呼吸症状。然后，我们调查了1990年2月至199,3年8月间在我们肺功能实验室接受检查的61例重症肌无力患者。在这61例患者中，12例有流量容积环，其中7例显示胸外上呼吸道梗阻模式。7例患者中有5例用力肺活量（FVC）为80%或更高。我们的数据表明上呼吸道梗阻在重症肌无力患者中比以前认识到的更为常见。总之，我们建议对重症肌无力患者进行流量容积环检查以评估其呼吸功能障碍。
