診断・治療に難渋した慢性咳嗽の1例

A Case of Persistent Dry Cough,Difficult to Diagnose and Treat

要旨　患者は67歳，男性．4歳と65歳時に2回の気管切開歴がある．2回目の気管孔閉鎖後，吸気性喘鳴，呼吸困難，乾性咳嗽，咽喉頭異常感が出現，徐々に増悪した．過去の気管切開部に一致した声門下と頸部気管の狭窄と，咽喉頭まで及ぶ胃食道逆流症に特徴的な披裂部粘膜の発赤・腫脹およびinter-arytenoid barを認めたため，気道狭窄に対する手術とともに術前からプロトンポンプ阻害剤であるランソプラゾール30mg/日の投与を行った．術後，吸気性喘鳴と呼吸困難は消失したが，1年経過後も咳嗽と咽喉頭異常感は不変であった．CYP2C19の遺伝子型を調査したところ，代謝活性の強いhomozygous EMであったため，CYP2C19に依存しない代謝経路を有するプロトンポンプ阻害剤であるラベプラゾール20mg/日に変更したところ，咳嗽，咽喉頭異常感は消失した．

　A 69-year-old male presented progressive inspiratory stridor and dyspnea with an abnormal sensation in his throat and dry cough. He had received tracheotomy for the infection of diphtheria when 1 year old. Subsequently, he received tracheotomy again during an operation for CABG in which intubation proved difficult at 65 years of age. Laryngeal fiberscopic examination revealed stenotic lesions in the subglottic area and the cervical trachea with swelling and redness of the arytenoid mucosa and the inter-arytenoid bar. We used surgical means to treat the stenotic lesions with administration of lansoprazole 30mg/day pre and post operatively. After the operation, inspiratory stridor and dyspnea were ameliorated, but the degree of abnormal sensation of the throat and dry cough could not be changed. Genetic analysis for genetic polymorphism of CYP2C19 genotype revealed that his genetic type of CYP2C19 was homozygous extensive metabolizer(homo-EM). After the change of medication from lansoprazole to rabeprazole(20mg/day), his persistent dry cough was completely cured within 5 weeks and there was improvement of the abnormal sensation in his throat.