What is ILO/EILO
ILO stands for “inducible laryngeal obstruction.” Similarly, EILO stands for “exercise-induced laryngeal obstruction.” These terms describe the phenomenon of narrowing (which can be obstructive) of the vocal folds and/or the structures above the vocal folds, such as the false vocal folds. This narrowing happens in response to some sort of stimulus or “trigger.” EILO’s trigger is exercise. This group of disorders were formerly called paradoxical vocal fold movement (PVFM), vocal folds dysfunction (VCD), or sometimes even referred to under the umbrella of irritable larynx syndrome (ILS).
When an attack happens, the patient feels as though their throat is closing up and they cannot get air in. Triggers can be from a wide range of things; irritants, exercise, or or psychogenic origin. Attacks can last several minutes. These attacks, while they can be scary, are not life threatening in nature. It is important to distinguish these attacks from other events that make it hard to breath, such as asthma attacks or anxiety attacks.
What Actually Happens During an Attack?
Normal breathing-in (or inspiration) has the vocal folds spread apart widely (or abducted). While the vocal folds may be slightly more closed when breathing out (or expiration), they are still open to allow air to pass through. In ILO, the vocal folds or structure above the vocal folds narrow when breathing in. This is the cause of the narrowing feeling in the throat. It may also cause sound when breathing in. Essentially, the structures of the larynx are doing the exact opposite of what they are typically supposed to do when breathing in. This “opposite” movement typically starts in response to the trigger. In ILO, it may be smelling a particular smell, where in EILO the attack happens during exercise.
How Common Is It?
EILO, which is a common form of ILO that is most prevalent among adolescents in young adults, is seen in about 7.1% of adolescents. It is also more commonly seen in women. Athletes, including those who perform at the competitive level, are commonly affected by this. Rates in adolescent athletes are greater and may be anywhere from 17.6-35.2%.
Seeking a Diagnosis
EILO (and ILO) are often misdiagnosed. Some patients report that care providers sometimes dismiss it as something else, which leads to a long time to receive a proper diagnosis. While it can also accompany other disorders, like asthma or anxiety, it is a distinct and different disorder. The difficulty in receiving a diagnosis can lead to frustration in those suffering from the condition. It is important to ensure that the symptoms the patient’s experience are from ILO/EILO and not a more serious condition. Providers who should be seen to help with a differential diagnosis include:
-Pulminologist
-Otolaryngologist (ENT)
-Speech Language Pathologist (SLP)
-Primary Care Physician (PCP)
The gold standard for evaluation, specifically for EILO, is to have continuous laryngoscopy during exercise (CLE) to be able to image the attack. This has a camera looking down at the vocal folds while the patient exercises to observe what happens during the attack. Not all clinics have the equipment required to do this, so laryngoscopy and videostroboscopy are still strong diagnostic tools to be used. Pulmonary measures should also be taken.
Treatment
More than 80% of patients who receive therapy from an SLP experience successful treatment. This success can be a decrease in frequency of attacks and/or greater ability to manage symptoms when they do occur. Breathing strategies, patient education, and counseling are key to ensuring a good clinical outcome.
Sources
Christensen, P. M., Thomsen, S. F., Rasmussen, N., & Backer, V. (2011). Exercise-induced laryngeal obstructions: Prevalence and symptoms in the general public. European Archives of Oto-Rhino-Laryngology, 268(9), 1313–1319. https://doi.org/10.1007/s00405-011-1612-0
Liyanagedara, S., McLeod, R., & Elhassan, H. A. (2016). Exercise induced laryngeal obstruction: A review of diagnosis and management. European Archives of Oto-Rhino-Laryngology, 274(4), 1781–1789. https://doi.org/10.1007/s00405-016-4338-1
McCracken, A. (2020, August 26). A young athlete’s breathing problems weren’t asthma. what were they? NPR. https://www.npr.org/sections/health-shots/2020/08/26/906047231/a-young-athletes-breathing-problems-weren-t-asthma-what-were-they
Sayad, E. (2023, January 2). Exercise-induced laryngeal obstruction. StatPearls [Internet]. https://www.ncbi.nlm.nih.gov/books/NBK556148/#:~:text=TheexactcauseandunderlyingmechanismsofEILO,airwayhyperresponsivenessinparttoneuronalstimuli.