The Misbehaving Larynx: Understanding Inducible Laryngeal Obstruction (ILO)
At Network Speech Pathology, we know that breathing and voice issues can feel frightening — especially when the cause isn’t obvious. One condition we’re seeing more of is Inducible Laryngeal Obstruction (ILO), also known as Paradoxical Vocal Fold Motion (PVFM) or vocal cord dysfunction (VCD). We’re referring to it today as “The misbehaving larynx” because it captures the sense of something fast, unexpected and out-of-sync happening in the voice box.
What is ILO?
ILO is a condition in which the vocal folds (laryngeal tissues) close when they should stay open during breathing. The person has a structurally and neurologically normal larynx, but the fold‑movement is inappropriate, resulting in symptoms such as sudden breathlessness (often worse on inspiration), throat tightness, a choking sensation or stridor/wheeze‑type sounds.
Rather than being a classic respiratory condition, this is a voice‑ or larynx‑driven phenomenon. The leading theory suggests the larynx becomes irritable or hypersensitive — much like an “over‑active guard dog” that responds at a lower threshold than normal. In other words, benign triggers cause the vocal folds to adduct when they should not.
Why is it different to other conditions?
One of the key distinctions we emphasise at Network Speech Pathology is that ILO is not the same as swallowing difficulties (dysphagia). With dysphagia, the issue occurs during eating or drinking (the airway or swallowing mechanism is compromised). With ILO, the trouble happens during breathing, typically not related to food or drink.
It is also often mis‑diagnosed as asthma, but there are key differences:
Onset: ILO attacks typically come on rapidly (seconds), often triggered, and resolve fairly quickly; asthma tends to onset more gradually (minutes to hours) with slower recovery.
Breathing phase: ILO often causes difficulty on inhalation (breathing in), whereas asthma typically affects exhalation.
Response to treatment: Asthma generally responds to inhalers; ILO does not respond to typical asthma treatment.
Associated features: ILO isn’t typically associated with lip, tongue, or face swelling (as might occur in anaphylaxis) and isn’t life‑threatening when identified and managed appropriately.
These differences matter because they guide the correct pathway for assessment and intervention.
What triggers ILO?
Because the larynx becomes hypersensitive, a wide range of everyday stimuli can trigger an episode. These include:
Dust, fumes, or perfumes
Air conditioning or cold‑air environments
Exercise
Odours or chemical exposures
Reflux
Chronic rhinosinusitis
Anxiety or heightened episodes of stress
Because triggers are often external or sensory in nature, therapy of ILO focuses on retraining the sensory‑motor response of the larynx rather than treating a structural lung disease. A multidisiplianry approach is encouraged, to optimise client outcomes.
what to do with ilo?
If you or someone you support has episodes of sudden throat tightness or breathlessness that don’t make sense in the context of asthma or swallowing problems, it may be time to consider ILO.
There are some wonderful resources available from the Centre of Excellence ILO/VCD Toolkit, which you can find via the link below:
At Network Speech Pathology, we provide tailored, evidence‑informed support (via telehealth as well as face‑to‑face) so that voice, breathing, and throat‑related issues don’t stay misunderstood or untreated.
If you’d like to discuss whether further assessment might be appropriate, or to learn more about laryngeal retraining and trigger management, please get in touch.
