Fauroux B, Trang H, Renolleau S, Boule M, Barois A, Tournier G
Service de Pneumologie Pédiatrique, Hôpital Armand-Trousseau, Paris.
Arch Fr Pediatr. 1992 Aug-Sep;49(7):633-5.
Extraocular, facial, bulbar and intercostal muscles are frequently affected in juvenile myasthenia gravis, especially during exacerbations. Acetylcholine receptor antibodies are often present in the blood in this type of myasthenic syndrome.
A girl presented with an exertional dyspnea at the age of 13 years, that improved after rest. All investigations were negative, except for lung function tests that showed a restrictive pattern. The diagnosis of juvenile myasthenia gravis was finally made at the age of 15 years because of the recurrence of sudden exertional dyspnea and a history of subtle weakness on repetitive movement leading to poor suckling, together with vocal and occasional swallowing difficulties. Dyspnea immediately improved after intravenous injection of 1 mg neostigmine, but the response was transient. No acetylcholine receptor antibody was found and a search for thymoma proved negative. Ambenonium chloride (Mytelase) was effective on clinical exacerbations, but the only improved test after 9 months of treatment was the functional residual capacity.
Anticholinesterase drugs must be tried in patients who present exertional dyspnea without bronchopulmonary or cardiac disease on the presumption of myasthenia gravis even when ocular or bulbar manifestations are absent.
眼外肌、面部肌肉、球结膜下肌肉和肋间肌在青少年型重症肌无力中常受影响，尤其是在病情加重期间。在这类重症肌无力综合征中，血液中常存在乙酰胆碱受体抗体。
一名13岁女孩出现劳力性呼吸困难，休息后有所改善。除肺功能测试显示限制性模式外，所有检查均为阴性。最终在15岁时诊断为青少年型重症肌无力，原因是劳力性呼吸困难突然复发，且有反复运动后轻微无力导致吸吮困难的病史，伴有声音嘶哑和偶尔的吞咽困难。静脉注射1毫克新斯的明后呼吸困难立即改善，但反应是短暂的。未发现乙酰胆碱受体抗体，胸腺肿瘤检查结果为阴性。氯化氨甲酰胆碱（酶抑宁）对临床病情加重有效，但治疗9个月后唯一改善的检查是功能残气量。
对于出现劳力性呼吸困难且无支气管肺部或心脏疾病的患者，即使没有眼部或球结膜下表现，也应假定为重症肌无力并试用抗胆碱酯酶药物。
