ILO Phenotypes
Inducible Laryngeal Obstruction (ILO) is a condition characterised by inappropriate narrowing of the laryngeal structures, resulting in patients experiencing a range of symptoms including pharyngeal tightness, dyspnoea, dysphonia, globus sensation, cough and stridor. It is considered a transient condition triggered by specific stimuli, with the most common triggers including airborne irritant exposures, talking, laughing, eating, exertion, emotional stressors and patients-presumed exposure to allergens. ILO is often accompanied with other concurrent comorbidities.
One challenge with this cohort is the variability with how they can present clinically and therefore the clarity with which we can understand the pathogenic pathways and furthermore our management approaches for each individual.
A new study conducted by Gardner et al (2025) has identified 4 different phenotypes of ILO, each with distinct characteristics. Based on their analysis, they discuss potential underlying pathology and proposed treatment approaches for each group.
The following table summarises the four different phenotypes as identified by Gardner et al (2025):
| ILO Phenotypes | Characteristics of Phenotype | Proposed Pathogenesis | Suggested Treatment Modalities |
|
1. Isolated ILO (32.8%, n=63) |
Triggered by inhaled and airborne exposures. No comorbidities. |
Heightened laryngeal sensitivity to airborne triggers. | Laryngeal retraining with a speech pathologist. |
|
2. Hyperventilation- associated ILO (41.7%, n=80) |
As above, PLUS: Plus associations with hyperventilation, anxiety and sinonasal disease. |
As above, PLUS: Mouth breathing and hyperventilation due to nasal obstruction and anxiety. Cortical contributions from anxiety. |
As above, PLUS: Breathing retraining with a physiotherapist to address the dysfunctional breathing patterns. Psychological support for anxiety. |
|
3. Polymorbid ILO (18.2%, n=35) |
As above, PLUS: Plus associations with hyperventilation, anxiety and sinonasal disease And additional comorbidities of lower airway obstruction (e.g. asthma and COPD), oesophageal reflux symptoms and obesity. |
As above, PLUS: This group demonstrated expiratory dominant paradoxical vocal fold motion, suggesting for those with lower airway obstruction, expiratory ILO could begin as an adaptive mechanical response to prevent lower airway collapse, providing end expiratory pressure. |
As above, PLUS: Appropriate medical intervention to manage lower airway obstruction and reflux. Response to laryngeal retraining occurred in only 75% of this group, suggesting greater attention to managing comorbidities may be necessary to optimise outcomes for this group. |
|
4. Pseudo allergic ILO (7.3%, n=14) |
Patient presumed exposure to allergen (in the absence of specific IgE sensitisation). |
Cortical-level factors. | Psychological support with allergen de-labelling. |
References: Gardner, L. S., Denton, E., Mahoney, J., Stojanovic, S., Pham, J., De Silva, A., Lin, T., Wong, M., Tay, T. R., Sverrild, A., Murthee, K. G., Hore-Lacy, F., Hoy, R., Hew, M., & Lee, J. (2025). Significance of Inducible Laryngeal Obstruction Phenotypes Identified by Latent Class Analysis. The journal of allergy and clinical immunology. In practice, 13(10), 2817–2825.e2.
EILO
Exercise Induced Laryngeal Obstruction (EILO) is a distinct phenotype characterised by inappropriate narrowing or closure of the upper airway at the vocal cords (glottis) and/or supraglottis during high-intensity exercise. Below is a case study of a recent patient with EILO, who completed treatment with us at Breathing Works.
Case Study - 18 Year Old, Male, Elite Triathlete
History of presenting complaint: 1-2km into the 5km run in a triathlon, he describes feeling his throat closes and feels he can’t get any air in. He needs to stop running to recover. He has a previous history of concussion in the year prior to symptom presentation.
Objective findings:
- Chronic mouth breathing at night with no sleep dysfunction.
- Lower thoracic expansion 3.5cm at T10 (ideal range 8-10cm) indicates poor mobility of lower rib cage
- Maximal Inspiratory Pressure: 117cmH2O (normal range 129-136cmH2O)
- Peak Expiratory Flow Rate: 650L/min (normal range 570-580L/min)
Treatment:
- Inspiratory Muscle Training for 3.5 months with progressive load increase.
- Feedback on lower costal breathing using Ultrasound Imaging of the diaphragm and mirror feedback to reduce overactivity of upper accessory breathing muscles.
- Nose breathing at rest with nasal hygiene practice including sinus rinse as necessary.
Outcome: He returned to racing triathlons at an elite level with no symptoms during the run. His lower thoracic expansion increased to 9cm; his MIP increased to 128cmH2O indicating better diaphragm strength and ability to offload upper airway and upper accessory breathing muscles.