20Q: Induced Laryngeal Obstruction - An Overview for Speech-Language Pathologists

From the Desk of Ann Kummer

Induced laryngeal obstruction (ILO) is when an individual experiences glottic or subglottic narrowing in response to a trigger. This can cause a sudden onset of inspiratory stridor and shortness of breath that can be severe. ILO is often triggered by intense exercise. In this case, it is referred to as exercise-induced laryngeal obstruction (EILO). EILO is particularly common among adolescents and young adult athletes.

Speech-language pathologists are increasingly called upon to see patients with suspected EILO. Therefore, I am excited that Dr. Brinton Fujiki has submitted this 20Q article to further explain the speech-language pathologist’s role in diagnosing and treating this disorder.

Dr. Robert Brinton Fujiki is a clinician scientist specializing in voice, resonance, and upper airway disorders – with particular interest in pediatric populations. He received his PhD at Purdue University and is currently a postdoctoral fellow at the University of Wisconsin-Madison. He is also a clinical speech-language pathologist in the voice and swallow and craniofacial anomaly clinics at American Family Children’s Hospital. His research interests include the diagnosis and treatment of voice disorders, induced laryngeal obstruction, and cleft palate in children. 

This course describes the nature of induced laryngeal obstruction, as well as the speech-language pathologist’s role in treating this disorder. Current diagnostic and treatment practices are outlined, as are research updates regarding the condition.

Now…read on, learn, and enjoy!

Ann W. Kummer, PhD, CCC-SLP, FASHA, 2017 ASHA Honors
Contributing Editor 

Browse the complete collection of 20Q with Ann Kummer CEU articles at www.speechpathology.com/20Q

20Q: Induced Laryngeal Obstruction -
An Overview for Speech-Language Pathologists

Learning Outcomes

After this course, readers will be able to: 

• Define and describe induced laryngeal obstruction.
• Describe the diagnostic criteria of induced laryngeal obstruction.
• Describe the comorbidities associated with induced laryngeal obstruction.
• Discuss the speech-language pathologist’s role in the evaluation and treatment of induced laryngeal obstruction.

Robert Brinton Fujiki

1. What is Induced Laryngeal Obstruction (ILO)?

Induced Laryngeal Obstruction (ILO) is characterized by trigger-induced laryngeal adduction that constricts the airway and causes dyspnea. ILO generally presents as inhalation difficulty and may include strider or wheezing. In addition to dyspnea, other symptoms of ILO may include a sensation of throat or chest tightness, cough, dysphonia, hyperventilation, and/or lightheadedness (Patel et al., 2015). Dyspnea is generally episodic, with sudden onset -often induced by an identifiable trigger such as physical exertion, stress, gastroesophageal reflux disease (GERD), scents, or exposure to an inhaled irritant (Sandage et al., 2022). Symptoms often resolve quickly upon exercise cessation or trigger removal.

2. What is the difference between ILO and Exercise Induced Laryngeal Obstruction (EILO)?

ILO can be used as a general term to refer to any type of induced laryngeal obstruction. Commonly used nomenclature, however, is generally based on symptom triggers. If dyspnea symptoms are triggered by physical exertion or exercise, the term Exercise Induced Laryngeal Obstruction (EILO) is used. If symptoms are induced by non-physical exertion-related triggers (i.e., scents, irritants, stress, etc.), the term ILO is used. You have probably noticed that ILO can be used both generally and to refer to non-exertion reduced symptoms specifically. This can be a little confusing, and it might help to think of ILO as a general condition with two subtypes: ILO (obstruction triggered by irritants, scents, or stress) and EILO (obstruction triggered by physical activity or exercise).

3. Is ILO the same as paradoxical vocal fold motion or vocal cord dysfunction?

Yes! ILO has been described using several different terms – the most common of which are paradoxical vocal fold movement (PVFM) or vocal cord dysfunction (VCD). You might even see terms such as exercised-induced asthma or laryngospasm used to describe ILO. PVFM and VCD are still commonly used terms. Consensus statements from Europe, however, argue that ILO is the most appropriate term for the condition (Christensen et al., 2015). Patients - especially pediatric patients - often find the terms ILO or EILO to be intimidating or frightening (justifiably so), so thorough explanation is often warranted.  

4. Why are there so many terms for EILO/ILO?

As our understanding of the condition has evolved, nomenclature has changed. This can be confusing, but more current terminology aims to describe the anatomy and physiology involved more accurately. A major reason to use the term ILO is that, in some cases, it can actually be supralaryngeal structures (i.e., the arytenoids) that obstruct the airway. Thus, the term vocal fold movement may be only partially accurate. Additionally, the term, vocal cord dysfunction, implies that the vocal folds are not working properly, which is not the case. The vocal folds are meant to adduct - just not during inhalation. Overall, the inconsistent nomenclature is unfortunate as it makes it difficult to find resources and research, as well as confuses patients and clinicians. This is further complicated by the fact that ILO treatment can span several medical specialties (i.e., otolaryngology, pulmonology, SLPs) that may use different terms. Hopefully, more consensus as to terminology will provide clarity.

5. How common is ILO?

The exact prevalence of ILO is unknown, as the condition is often mistaken for asthma. Population-based prevalence studies from Europe indicate that between 5.7% and 7.5% of teenagers and young adults present with EILO (Christensen et al., 2011; Johansson et al., 2015). Additionally, it is estimated that as many as 8.1% of recreational adolescent athletes experience EILO symptoms (Ersson et al., 2020). It has also been estimated that between 3% and 5% of pulmonology rehabilitation patients present with an ILO component to dyspnea (Kenn & Hess, 2008). Additionally, as many as 5% of elite athletes may experience ILO symptoms (Hanks et al., 2012).

6. Who is at increased risk for ILO?

Data are limited, but there are some patterns evident in the literature. ILO can occur in patients of all ages. It has been estimated that 30% of cases occur in pediatric populations (Zalvan et al., 2021). Although anyone can be affected, evidence suggests that EILO is particularly common in middle to high-school-aged female athletes (Hanks et al., 2012). Many patients with EILO are high-performing individuals and, in some cases, anxious. Although additional research is needed, preliminary evidence suggests that females may be at increased risk.

7. What causes ILO?

The etiology of ILO remains unclear. It has been hypothesized that hypersensitivity of the upper airway, laryngeal dystonia, or psychological conditions may contribute to --or trigger-- the condition (Patel et al., 2015). Although no single cause has been empirically substantiated, studies have documented aberrant laryngopharyngeal sensation in patients with ILO (Cukier-Blaj et al., 2008; Murry et al., 2010). It has been hypothesized that ILO symptoms stem from neural plasticity in the central nervous system, which regulates sensorimotor pathways (Domer et al., 2013). Neurosensory alterations can include elevated laryngeal sensitivity and lowered threshold for activation of the laryngeal adductor reflex, making the vocal folds predisposed to adduct for airway protection (C. L. Ludlow, 2015).

8. Do EILO and ILO present similarly clinically?

We recently performed a study examining this question in the pediatric population (Fujiki et al., 2023). Children and adolescents with ILO and EILO presented with unique but overlapping clinical profiles. Although all patients experienced dyspnea, those with EILO experienced more symptoms associated with physical exertion, such as hyperventilation and cough. Patients with ILO presented with higher rates of comorbidities consistent with irritable larynx syndrome as well as comorbid anxiety. The good news is that therapy was equally effective among both groups. Additional research is needed to determine if these patterns hold true in adults.

9. I’ve heard that patients with ILO experience a high prevalence of behavioral health comorbidities. Is this true?

We recently completed a study that indicated that in comparison to the general population,  rates of anxiety, depression, and post-traumatic stress disorder (PTSD) were higher in both adults and children with ILO (Fujiki et al., Submitted). This study supports past work suggesting that anxiety, in particular, is elevated among these patients (Gavin et al., 1998; Husein et al., 2008). At this time, no causal relationship between ILO and behavioral health conditions has been substantiated, but there does appear to be an association between the two entities. More research will be needed to determine why. The research we do have suggests that screening patients for comorbid behavioral health conditions might be helpful to ensure that the proper referrals can be made. There have been studies suggesting that ILO therapy is more effective if behavioral health comorbidities are addressed by the appropriate professionals (Cristel et al., 2020).

10. How is ILO diagnosed?

At a minimum, laryngoscopy is needed to diagnose ILO. Ideally, vocal fold adduction upon inhalation should be visualized upon exam for a patient to receive the diagnosis. However, this is not always feasible in clinical facilities. Continuous laryngoscopy during exercise (CLE) is the preferred procedure for diagnosing EILO (Hull et al., 2019); however, the technological setup required for this imaging technique is currently extremely limited in the United States. CLE requires patients to undergo nasoendoscopy while exercising on a treadmill or bike. Currently, EILO is usually diagnosed using laryngoscopy immediately following physical exertion (Harvey et al., 2022). For ILO (cases where exercise is not a trigger), evidence suggests that patients should ideally be exposed to the irritant that triggers their symptoms while nasoendoscopy is performed (Vertigan et al., 2022). Again, the setup for this procedure is currently limited in the United States. At a minimum, however, laryngoscopy should be performed, and other conditions (e.g., foreign body inhalation, asthma, other respiratory diseases) must be excluded by specialized physicians.

11. What financial costs are associated with obtaining an ILO diagnosis?

As ILO is (in part) a diagnosis of exclusion, patients often see multiple providers and undergo numerous procedures prior to diagnosis. Evidence indicates that, for adults, the economic burden of obtaining an ILO diagnosis is considerable, costing a median of $8,625.00 over an average of 33 months (Lunga et al., 2022). These expenditures have been predominantly driven by pharmaceuticals, followed by various diagnostic tests to rule out other conditions. We have recently completed a similar study in children, which confirms that this is the case in pediatric populations as well. We also found that economic deprivation may affect ILO-related care, as children from poorer neighborhoods were prescribed more pharmaceuticals, while children from more affluent areas received more diagnostic testing. This is concerning, given that pharmaceuticals are generally ineffective for treating ILO.

12. Why is diagnosing ILO so challenging?

Diagnosing ILO can be challenging because the condition shares common symptoms with asthma and other respiratory conditions. Since asthma is widely recognized among general practitioners and the general population, patients with ILO often receive asthma treatments/testing such as inhalers or pulmonary function testing/spirometry. This is unfortunate because inhalers are of limited value for this population (Ivancic et al., 2021). In addition, although spirometry may effectively identify asthma, we recently performed a study suggesting that the procedure does not effectively differentiate ILO from other common respiratory conditions, such as chronic cough or even mild asthma. The episodic nature of ILO symptoms can also make it difficult for patients and providers to identify symptoms and their etiology. Often, patient symptoms have had time to escalate and increase in severity before a diagnosis is made. This may be because patients saw multiple providers and/or waited for specialist appointments, but it can also be because patients were unsure whether they needed to seek treatment until symptoms became more severe. Regardless, clinicians should be aware that patients have often been experiencing symptoms for a long time before a diagnosis is made.

13. Can you treat ILO if you don’t have access to advanced equipment?

This is an interesting question. ILO cannot be diagnosed without specialized equipment; however, after a diagnosis is obtained, therapy can be effectively administered without major specialized equipment. Research suggests that intervention with an SLP is effective in helping children and adults manage ILO (Drake et al., 2017; Fujiki, Olson-Greb, Braden, et al., 2023), and it is well within our scope of practice. For patients with exercise-induced symptoms, SLPs may need to get creative to find a place for patients to exert themselves physically. I have run with patients outside, in the hall, or on the stairs if a treadmill was unavailable. If a treadmill is available – this is often the most effective way for patients to practice managing symptoms (and not as tiring for the SLP as we can stand by them and observe). In general, it is helpful to coordinate with the physician who made the diagnosis in order to ensure that best practice guidelines have been followed. In my experience, physicians sometimes send patients to SLPs for therapy when they are unsure about the patient’s diagnosis. While determining whether therapy strategies are effective can have diagnostic value, this can be problematic if other conditions have not been ruled out. If a patient is working hard in therapy and does not experience improvements in 2-3 sessions, the SLP should likely consider referring them back to a physician.

14. What is the treatment for ILO?

The primary treatment for ILO is therapy with a speech-language pathologist (SLP) (Mahoney et al., 2022). This is sometimes referred to as respiratory retraining. The effectiveness of SLP therapy in addressing ILO has been substantiated in the literature (Drake et al., 2017; Fujiki, Olson-Greb, Braden, et al., 2023; S. Ludlow et al., 2022; Zalvan et al., 2021). Therapy can improve scores on dyspnea scales (Fowler et al., 2015), facilitate a return to physical activity (Fujiki, Olson-Greb, Braden, et al., 2023), and reduce reliance on asthma medications (Kramer et al., 2017). Although objective measures quantifying symptoms of ILO are rare, multiple studies have documented patient-reported reductions in ILO symptoms following therapy. Evidence suggests that these gains are generally retained long-term (Doshi & Weinberger, 2006), thus avoiding unnecessary medical visits (Baxter et al., 2019).

15. What are the components of therapy?

Therapy usually consists of education regarding the nature of the disorder, training of lower thoracic breathing (Chen et al., 2017), teaching rescue breathing techniques, and learning to apply these techniques to prevent and improve symptoms when they occur. This often requires a lot of repetition and practice on the patient’s part because using breathing techniques can be difficult in the moment dyspnea appears. We recently did a study where we talked to the parents of children with ILO, and parents indicated that getting children to practice the techniques learned in therapy was difficult. While this is not shocking, it does mean that patients may not get as much practice as we would hope. The techniques may initially appear simple, but they become more difficult when patients are symptomatic – because being unable to breathe is scary! It is important to emphasize that rescue breathing techniques will likely only work if the patient is very familiar with them before symptoms occur. For many patients, stress also aggravates symptoms, which makes using the techniques even more difficult if they cannot rely on some muscle memory. To address general tension or stress, relaxation techniques are sometimes incorporated, as are mindfulness techniques (Diab et al., 2022; Matsumoto & Smith, 2001) and circumlaryngeal massage (Roy et al., 1997). Comorbidities falling outside the scope of SLP practice (i.e., reflux, allergies) should be addressed by the appropriate physicians. Considering the overlap of ILO and anxiety, referral to--and collaboration with--mental and behavioral health specialists may also be warranted.  

16. What rescue breathing techniques are most effective?

Data regarding the comparative effectiveness of therapeutic strategies are not available. In all likelihood, the ideal technique varies for each patient. Breathing training should be individualized to patient needs and athletic activities. This training often includes pursed lip breathing, sniff inhalation, and/or biphasic inspiratory breathing with pursed lip exhale and establishing lower thoracic (abdominally driven) breathing patterns (Johnston et al., 2018; Patel et al., 2015; Shaffer et al., 2018). Breathing strategies all use partial oral occlusion to promote laryngeal abduction through negative back pressure. In my personal experience, pursed lip breathing or biphasic inhalation with pursed lip exhale are easiest for patients with exercise-induced symptoms, as they can be done quickly during physical exertion. At rest, sniff inhalation is also useful for patients; however, it can be tricky for those with a lot of nasal congestion. Regardless of what strategy is employed, it is important to ensure that the patient is breathing at a reasonable pace (particularly pediatric patients sometimes do the rescue techniques really quickly and then feel as though they are going to hyperventilate). Sometimes, focusing on exhalation is helpful for pacing patients – or in some cases, the clinician may remind the patient that exhalation should be longer than inhalation. It is also important to ensure that the patient is breathing “low” without tightening or raising the shoulders upon each inhale. In my experience, all breathing strategies require significant practice in the setting where symptoms occur to really be effective.

17. Should EILO and ILO be treated differently?

More research is needed; however, the limited evidence available suggests that the same rescue breathing techniques are effective for both conditions. One important factor, however, is that patients must be comfortable using therapy strategies in the context of their symptom triggers. Thus, patients with EILO must be able to use therapy techniques during exercise, and ILO patients in the presence of their triggers. In my experience, helping patients effectively use therapy techniques while they are symptomatic is the most challenging aspect of therapy. As patient triggers are rarely perfectly replicated in the therapy room – it is important to talk to patients about how they will implement rescue breathing techniques on their own. We can help them practice a lot, but we are frequently not there for actual dyspnea episodes. So the patient should have a plan in place. This plan should include specific rescue breathing techniques and clear guidance on when and how long they should be used.

18. How long does therapy for ILO take?

We recently performed a series of studies examining this question. We found that 112 pediatric patients required an average of 3.4 sessions of therapy prior to discharge, with over 80% percent of patients being discharged in under five sessions (Fujiki et al., 2022). In this study, a history of upper airway surgery or a behavioral health diagnosis increased the duration of therapy. In another study, we found that 350 adults with ILO required an average of 3.59 sessions of therapy. In adults, therapy duration was longer for patients with a behavioral health diagnosis, a voice complaint, or reduced physical activity from ILO symptoms.

19. What outcome measures have been developed for tracking therapeutic progress?

Overall, therapy outcome measures are lacking. Generally, therapeutic progress is tracked using patient report. We can certainly argue that the patient’s experience is the most critical outcome of intervention. There have been several patient-reported measures developed. These include The Dyspnea Index and the Vocal Cord Dysfunction Questionnaire. Specific to EILO, the Exercise-Induced Laryngeal Obstruction Dyspnea Index has also been validated. Future research will hopefully supplement patient report measures with objective assessments. In the meantime, for patients with exercise-induced symptoms, clinicians may time how long patients can exercise without experiencing symptoms or how quickly they can recover from symptoms using therapy techniques. Some clinicians have patients count the number of dyspnea episodes; however, this can be difficult for patients to remember. At this point, patient report is likely the best option we have. 

 20. How long do the effects of therapy last?

Unfortunately, longitudinal studies regarding therapeutic outcomes are lacking. We recently did a study that documented that teenagers with EILO continued to experience improvements in symptoms six months after discharge from therapy (Fujiki, Olson-Greb, Braden, et al., 2023). With regard to adults, we performed a retrospective study of 350 adults with ILO and found that 8% returned for additional therapy following discharge with a reoccurrence of symptoms. ILO is known to be somewhat cyclical in nature, so more research on maintaining intervention gains is sorely needed.

In summary, ILO can be both frightening and debilitating for patients and their families. It is often time-consuming and expensive for patients to obtain an accurate diagnosis. Those with less access to specialized health care may not receive an accurate diagnosis, and many may be prescribed medications they do not need (e.g., inhalers). On the bright side, intervention with an SLP is effective in helping individuals manage ILO—and in relatively few sessions!  We all need to work to improve the identification of ILO and to make diagnosis and treatment obtainable and equitable for all.

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