Exercise-induced laryngeal obstruction. Diagnostic procedures and therapy

Abstract

Introduction: Exercise-induced inspiratory stridor (EllS) is not uncommon in adolescents. lt can be caused by airflow obstruction at different levels of the airways but most often at the laryngeal level. Although the larynx may function perfectly normally during quiet breathing, obstruction of airflow through the larynx can cause respiratory distress and stridor during exercise. ln the literature, there is confusion over the terminology used for this phenomenon. One of the more recent terms, exercise- induced laryngeal obstruction (ElLO) has the advantage that previous terms can be included into its framework. Laryngeal obstruction typically induces inspiratory stridor as opposed to asthma causing expiratory wheeze. Still, these conditions are all too often mixed up, and maltreatment can be a consequence. ln order to ease the differentiation between these conditions, a setup for continuous laryngoscopy during exercise had been established prior to the commencement of this work (Heimdal et al., 2006). Aims: The first aim of this thesis was to apply the continuous laryngoscopy exercise (CLE)-test on a larger series of patients experiencing exercise-induced inspiratory stridor (EllS). Clinical application of the test uncovered a need for a more objective evaluation of findings, and therefore the second aim was to develop a scoring scheme that could be used to grade the level and severity of laryngeal obstruction and to assess the reliability and validity of this CLE-test score. We experienced that some patients had serious problems with respiratory distress during exercise and therefore we offered surgical treatment to patients selected by clinical criteria; i.e. if the patients experienced severe distress during exercise, were highly motivated for surgical treatment in order to reduce symptoms, and we could observe a severe obstruction of the laryngeal inlet during the CLE-test. The third aim was therefore to use the CLE-test in order to reveal the effect of surgical treatment on the laryngeal motion and symptoms. As most ElLO patients are teenagers, one could hypothesise that a natural development and enlargement of the larynx during growth would reduce the laryngeal obstruction during exercise. The fourth aim of this thesis was therefore to assess the natural course of ElLO and to assess the long term effect of surgical treatment of supraglottic ElLO. Methods: The CLE-test was performed according to the description by Heimdal and co-workers (2006). Video and sound recordings were edited into new data files and could thereby be reviewed in a random order without any clinical information in order to secure a best possible objective assessment. Additional information about symptoms was revealed by questionnaires and visual analogue scores (VAS). ln the follow-up study, change in symptoms of exercise-induced breathing distress, level of activity, and the impact of symptoms on daily life activity was addressed in questionnaires sent by mail. All surgically treated patients and selected patients from the initial part of study were invited to perform a second CLE-test. Results: ln the first study, the CLE-test turned out to be feasible in order to reveal level and severity of laryngeal obstruction in ElLO patients. We observed that the larynx could be obstructed only at the supraglottic level but most often in combination with obstruction also at the glottic level. The latter was rarely found to be the sole cause of EllS. When CLE-scores of laryngeal obstruction were evaluated in the second study, inter- and intra-observer agreement was moderate to very good. The test was found to be interpretable and also valid as scores were significantly correlated with the severity of respiratory distress symptoms when assessed both by the patients and by observers. The third study included l0 patients for surgery according to the clinical criteria. The patients reported a better ability to breathe while exercising, after surgical treatment, as revealed by VAS scores. Postoperatively, the CLE-test showed an increased abduction of the supraglottic structures during both moderate and maximal exercise. The fourth study included; re-examination of l4 patients, initially tested when teenagers, with a second CLE-test at adult age; a re-examination of l9 of 24 surgically treated patients and; follow-up concerning symptoms of 73 of the 94 patients invited to the study. This study showed that most subjects experienced symptom relief during the observation time, but more so in the surgically treated than untreated patients. Comparison of l9 pre- and postoperative CLE-tests showed a significant improvement in the ability to keep the larynx open, while exercising, in the surgically treated group. On the contrary, little change was observed in laryngeal motion in l4 re-tested, untreated patients. Concluding remarks: We conclude that exercise-induced laryngeal obstruction can be visualized by the CLE-test and that the obstruction of the larynx in ElLO patients is most often due to an inward rotation of the aryepiglottic folds, frequently followed by a narrowing of the glottic space, and seldom solely due to glottic adduction. ln some cases, major distress and panic reactions can be the endpoint of this phenomenon. The severity of obstruction can be graded by the CLE-score in a reliable and valid manner. Surgery of exercise-induced laryngeal obstruction can be an adequate treatment in strictly selected cases, depending of severity of symptoms, degree of obstruction, and motivation of the patient. EllS due to ElLO does not seem to recover spontaneously in youngsters. Reduced physical activity may give the impression that the laryngeal function has improved.