Upper Airway Obstruction Presenting as Exercise-induced Asthma Report

It is a well known clinical dictum that all that wheezes is not asthma. For example, focal obstruction by a mass lesion or a foreign body anywhere in the tracheobronchial tree may result in wheezing. In recent years, several reports have appeared of patients who were initially diagnosed as having asthma (https://onlineasthmainhalers.com) who later proved to have physiologic or functional obstruction due to vocal cord adduction during expiration, resulting in wheezing. We present a patient who exhibited wheezing from laryngeal obstruction only during exercise. To our knowledge this is the first time such a syndrome has been described.

Case Report

A 32-year-old woman presented to the allergy clinic with a ten-year history of wheezing during exercise. She participated in track during college, at which time she first noticed episodes of noisy, labored breathing during extended periods of running. On one occasion she briefly lost consciousness with a particularly severe episode, after which her coach limited her participation to short events. She had no angioedema, urticaria, or flushing during this or any other episodes. She continued to jog after college and at the time of her presentation she stated that after running for 10-15 minutes her breathing would get progressively louder, with wheezing and air hunger, forcing her to stop. The wheezing would persist for up to five minutes before subsiding. She regularly coughed during the hours after exercise with the occasional production of clear sputum. The onset of symptoms was earlier if her pace was brisk, and the wheezing was worse in cold weather or when she was jogging infrequendy; with regular physical conditioning her symptoms tended to be milder and to occur later.

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Respiratory Symptoms

She has no respiratory symptoms at other times, and there was no personal or family history of atopic diseases. Her past medical history was notable for an episode of nephrolithiasis, mitral valve prolapse, and a long history of non-seasonal nasal congestion with post-nasal drip. She denied any knowledge of respiratory distress or stridor as a neonate or an infant. She denied any symptoms referable to gastroesophageal reflux, and used no medications.

Physical examination was remarkable only for a late systolic murmur; the lungs were clear. Skin testing showed positive reactions to house dust and mites. Baseline spirometry was normal, and an initial methacholine challenge test was negative.

She underwent successive trials of inhaled metaproterenol, cromolyn sodium, and a combination of the two, without significant benefit. In further discussion, she noted that most of the wheezing seemed to originate in her upper airways, which led us to repeat the methacholine challenge. During this challenge, results of spirometry remained normal, but following the final dose of methacholine (25 mg/ml) we obtained a flow-volume loop which showed flattening of the inspiratory limb. This returned to normal within several minutes. The patient then ran outdoors in cold air ( —1.1°C [30°F]) and returned with obvious inspiratory stridor, accompanied by markedly labored breathing and use of the accessory muscles of respiration. On auscultation, the inspiratory sound was transmitted to all lung fields, but was loudest over the neck. The stridor lasted one to two minutes and then subsided rapidly. Again, the inspiratory flow curve showed flattening with immediate resolution.

medical-examinationSubsequendy she exercised on a treadmill in the pulmonary function laboratory. While symptomatic, she performed spirometry and underwent flexible fiberoptic laryngoscopy. Symptoms appeared while running 5 mph at a 10 percent grade. Results of pulmonary function tests are shown in Table 1. After exercise there was a symmetrical decrease in FVC and FEVi without change in the FEVj percent or peak expiratory flow rate. Her peak inspiratory flow rate fell by 28 percent and the ratio of mid-expiratory to mid-inspiratory flows became abnormal (normal <1). Flow volume loops before and after exercise are shown in Figure 1. There is definite flattening of the inspiratory limb of the loop after exercise, with no change in the expiratory limb. The decreased inspiratory flow rates are consistent with a variable inspiratory extrathoracic airway obstruction. There was no suggestion of obstruction during expiration. She was unable to complete the forced expiration maneuver because of dyspnea; this resulted in the lower FEV1 and FVC after exercise.

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Under direct vision, during the period of post-exercise stridor, one of us (BH) observed inspiratory prolapse of the corniculate and cuneiform cartilages in the posteroinferior portion of the aryepiglot-tic folds over the laryngeal vestibule, thus narrowing the supraglottic aperture (Fig 2). This could not be reproduced with a forced inspiratory maneuver. The vocal cords were widely abducted during inspiration. One of us (WJM), who has exercise-induced asthma and a markedly positive methacholine challenge test, served as a control. After running on the treadmill, with wheezing present, the supraglottic structures were stable in their normal position during inspiration, and the vocal cords were widely abducted.

Laryngoscopic examination of the patient during quiet breathing showed that the posterior surface of the arytenoids was erythematous. Since there was no history of gastroesophageal reflux, we theorized that the arytenoid inflammation resulted from postnasal drip and was contributing to her symptoms. Therefore, she was placed on therapy with a topical steroid nasal spray. Subsequently, she has had considerable further improvement in her stridor and post-exercise cough. She now regularly runs six miles at eight minutes per mile with stridor occurring only during the last few minutes of the run. A repeat indirect laryngoscopic examination six weeks after beginning therapy with the topical steroid nasal spray showed complete resolution of the erythematous arytenoids.

Flow-volume loops

 

Figure 1. Flow-volume loops obtained before treadmill exercise (left) and immediately after stopping exercise (right). A sharp cut-off and flattening is seen on the post-exercise curve which returned to baseline within two minutes after stopping exercise.

 

normal endolarynx

Figure 2. Photograph of a normal endolarynx showing area of comiculate (asterisk) and cuneiform cartilages (cross) in posteroin-ferior portion of aryepiglottic folds which collapsed over the laryngeal vestibule (P, posterior cords; A, anterior cords).

Table 1 — Results of Pulmonary Function Tests

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Baseline Immediately After Exercise 60 Seconds Later
FVC 4.49 (107%) 3.66 (87%) 4.12 (98%)
FEVj 4.28 (129%) 3.60 (108%) 4.00 (120%)
FEV,% 95 98 97
PEF (L/s) 9.4 9.2 9.5
PIF (L/s) 8.3 6.0 8.8
FEFsq/FIFjo 0.76 1.07 0.73