Exercise inducible laryngeal obstruction: diagnostics and management.

Obstruction of the central airways is an important cause of exercise-induced inspiratory symptoms (EIIS) in young and otherwise healthy individuals. This is a large, heterogeneous and vastly understudied group of patients. The symptoms are too often confused with those of asthma. Laryngoscopy performed as symptoms evolve during increasing exercise is pivotal, since the larynx plays an important role in symptomatology for the majority. Abnormalities vary between patients, and laryngoscopic findings are important for correct treatment and handling. The simplistic view that all EIIS is due to vocal cord dysfunction [VCD] still hampers science and patient management. Causal mechanisms are poorly understood. Most treatment options are based on weak evidence, but most patients seem to benefit from individualised information and guidance. The place of surgery has not been settled, but supraglottoplasty may cure well-defined severe cases. A systematic clinical approach, more and better research and randomised controlled treatment trials are of utmost importance in this field of respiratory medicine.

Larynx during exercise: the unexplored bottleneck of the airways.

Exercise-induced shortness of breath is not uncommon in otherwise healthy young people. Based on the presenting symptoms alone, it is challenging to distinguish exercise-induced asthma (EIA) from exercise-induced obstruction of central airways, sometimes leading to diagnostic errors and inadequate treatment. Central airway obstruction usually presents with exercise-induced inspiratory symptoms (EIIS) during ongoing exercise. EIIS tends to peak towards the end of an exercise session or immediately after its completion, contradicting symptoms of EIA typically peaking 3-15 min after the exercise has stopped. EIIS is usually associated with some form of laryngeal obstruction. Transnasal flexible laryngoscopy performed continuously throughout an incremental exercise test from rest to exhaustion or to intolerable symptoms is usually diagnostic, and also provides information that is important for further handling and treatment. Reflecting the complex anatomy and functional features of the larynx, exercise-induced laryngeal obstruction (EILO) appears to be a heterogeneous condition. Contradicting previous beliefs, recent literature suggests that laryngeal adduction in a majority of cases starts in supraglottic structures and that vocal cord adduction (VCD) most often occurs as a secondary phenomenon. However, EILO is poorly understood and more and better research is needed to unravel causal mechanisms. The evidence base for treatment of EILO is weak. Speech therapy, psychotherapy, biofeedback, muscle training, anticholinergic aerosols have all been applied, as has laser supraglottoplasty. Randomized controlled trials with well-defined and verifiable inclusion and success criteria are required to establish evidence-based treatment schemes.

Laryngeal movements during inspiratory muscle training in healthy subjects.

BACKGROUND: Inspiratory muscle training (IMT) has been used to treat patients with exercise-induced vocal cord dysfunction (VCD); the theoretical basis being the close relationship between the diaphragm and the posterior cricoarytenoid muscle, which is the main abductor of the larynx. Before launching a treatment protocol in patients with VCD, we aimed to substantiate this theory by performing laryngoscopy in healthy subjects during standardized IMT programs. METHODS: Twenty healthy volunteers at mean age 24 years were examined with video-recorded continuous transnasal flexible laryngoscopy while performing standardized training programs using a resistive loading IMT device (Respifit S). All subjects were exposed to two modes of training, that is, the resistance set to generate mouth pressures ≥80% of the maximal attainable inspiratory mouth pressure (PImax) and 60-80% of PImax. Laryngeal movements were scored in retrospect from the video recordings by a senior laryngologist. RESULTS: At pressure settings of ≥80% of PImax, laryngeal movements could not be assessed in one subject. Abduction was observed in 10 (53%) subjects, six to a maximal extent and four to a moderate extent. At pressure settings of 60-80% of PImax, abduction was observed in 18 (90%) subjects, seven to a maximal extent and 11 to a moderate extent. CONCLUSIONS: IMT can produce laryngeal abduction in healthy subjects, and training programs may conceivably contribute positively in patients suffering from laryngeal adduction during exercise. Individual response patterns varied between subjects and individualized programs seem crucial for effect. Use of high resistances seemed to be counterproductive.