Exercise-induced laryngeal obstruction: a common and overlooked cause of exertional breathlessness

PREVALENCE

The diagnosis of EILO is most often made in adolescents. A recent cross-sectional study of 12–13-year-olds in Sweden demonstrated a population prevalence of approximately 6%.³ Another study has shown that EILO may be as prevalent as exercise-induced bronchoconstriction, explaining ‘treatment-refractory’ symptoms in around a quarter of young athletic patients referred with exertional respiratory symptoms.⁴ Nielsen et al found EILO coexisting with exercise-induced bronchoconstriction in just over 10% of individuals, perhaps explaining why ‘partial’ resolution of symptoms is seen in some young patients treated with inhaler therapy.⁴

PRESENTATION

EILO typically presents as a young athletic female, <20 years, reporting shortness of breath, increased respiratory effort, throat discomfort, and/or chest tightness and a wheeze that develops during intense exercise, often during competitive events.

The differential diagnosis for exertional dyspnoea is broad and requires an initial exclusion of ‘red flag’ respiratory and cardiac symptoms and signs, for example, chest pain, palpitations, haemoptysis, and the presence of cardiac signs such as a cardiac murmur.

Classically the ‘wheeze’ of EILO occurs during the inspiratory phase of the breathing cycle and is high pitched in quality, that is, stridulous. This differentiates it from the expiratory polyphonic basal wheeze heard with lower-airway narrowing.

Symptom onset in EILO usually occurs during strenuous exercise and settles rapidly (within 5 minutes of exercise cessation). This contrasts with exercise-induced bronchoconstriction, in which symptoms occur following exercise cessation (5–10 minutes). Patients with EILO not infrequently report cough or throat discomfort that can persist for some time following exercise.

DIAGNOSTIC CRITERION AND ASSESSMENT

Several clinical features can be useful in differentiating EILO from exercise-induced bronchoconstriction (Table 1). It should be noted, however, that questions thought to be of discriminatory value (for example, difficulty ‘breathing in’ when exercising) have actually been shown to have poor diagnostic value when studied formally. Likewise, there is no evidence to suggest that a diagnosis of EILO can be reliably confirmed or refuted by resting or post-exercise spirometry, or by peak flow measurement.⁵ Moreover, because EILO occurs during strenuous exercise, investigations performed in a ‘resting’ state are unlikely to be diagnostically helpful.

It is thus often useful for a clinician to observe a patient as they develop symptoms, for example, when performing the sport that triggers symptoms. If this is not feasible, then the authors have previously found ‘selfie’ mobile-phone-type video recordings of patients when they develop symptoms to be informative. This subsequently allows the clinician to review the characteristics and onset of symptoms, and better discern the nature of the wheeze. The diagnostic accuracy of this approach is yet to be studied formally, although it may prove helpful.

The ‘gold-standard’ means for diagnosis involves real-time evaluation of laryngeal movement during exercise. This test, termed the continuous laryngoscopy exercise (CLE) test, utilises a flexible laryngoscope in a fixed position on specialist headgear (Figure 1), allowing continuous video assessment of laryngeal movement while a patient performs exercise.

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Figure 1.

The continuous laryngoscopy exercise (CLE) test.

During exercise there is normally complete abduction of the laryngeal structures to maintain laryngeal patency and optimise flow. Thus, EILO is diagnosed on the basis of the development of abnormal degree of adduction of the supra-glottic structures (akin to laryngomalacia) and/or inappropriate closure of the glottis (that is, vocal cords) during the test (Figure 2). This closure generates turbulent flow and increased resistance, which in turn promotes laryngeal closure, resulting in dyspnoea and inspiratory stridor. The CLE test allows patients to visualise where their symptoms are arising from and can also inform treatment. We suggest that individuals be referred for specialist review and a CLE test if there is diagnostic uncertainty +/− a poor response to therapies, and clearly if surgical intervention is being considered.

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Figure 2.

Glottic and supra-glottic exercise-induced laryngeal obstruction (EILO). NB Static images taken from CLE with exercise narrowing occurring during inspiratory phase of breathing cycle. Severity of closure is scored by grade of closure (that is, with Grade I as minor closure and grade III as severe); closure above grade II is taken as significant. Adapted from Nielsen et al.⁴ © Wolters Kluwer. Used with permission.

MANAGEMENT

The first step in managing EILO is to discuss the nature of the problem with the patient affected and for the clinician to consider and highlight the fact that, providing there is not a diagnosis of coexisting exercise-induced bronchoconstriction, medication use can be rationalised. Literature is replete with reports of patients who have been unnecessarily treated with asthma therapies for several years prior to their diagnosis of EILO.⁴

Time should be spent addressing and minimising the effect of any laryngeal irritants (for example, nasal disease and reflux) and a discussion regarding strategies to improve laryngeal hygiene (for example, avoiding smoking, regular fluid intake, and avoiding dietary caffeine).

Physiotherapy and speech and language therapy currently form the basis of treatment, utilising breathing control techniques to improve laryngeal abduction during exercise. Basic strategies include providing focus on nasal breathing to increase humidification of air, inspiratory muscle training, and overall promotion of a diaphragmatic-predominant breathing pattern.

Emotional stressors may contribute to the development of symptoms in some individuals and certainly in the context of competitive environments. Supportive interventions including counselling and/or relaxation therapy should be considered.

Individuals with severe EILO that remains refractory to the interventions described above can be treated surgically.⁶ Laser aryepiglottoplasty involves surgical de-bulking of redundant tissue, such as prominent cuneiform tubercles in the aryepiglottic folds that can create obstruction of the laryngeal inlet. The precise place of surgery in the management algorithm of EILO is yet to be fully established.

IMPORTANCE OF TOPIC

It is likely there are many young individuals within the general population who are misdiagnosed as having exercise-induced asthma and who would benefit from the recognition and treatment of EILO.