Inducible Laryngeal Obstruction

What is Inducible Laryngeal Obstruction?

Inducible Laryngeal Obstruction (ILO) is used to describe a throat disorder that typically affects your ability to breathe in (inspiration). It causes inappropriate narrowing or closure of the vocal cords or structures in the voice box.

Inducible: symptoms are intermittent and can be triggered by different factors
Laryngeal: Voice box
Obstruction: prevents passage of air, making it more difficult to breathe

ILO can mimic or coexist with other respiratory disorders such as asthma, chronic cough or chronic obstructive pulmonary disease (COPD). Therefore diagnosis and treatment can be challenging. It is important that you undergo specialist assessment to diagnose and manage this condition effectively.

Understanding the cause, symptoms and diagnosis of ILO is crucial in helping you manage this.

Upper airway and breathing

Your voice is produced in your voice box (also known as your larynx) which sits at the top of your windpipe (trachea). Inside your voice box are your vocal cords. Air from your lungs travel up the windpipe and vibrate your vocal cords to produce your voice.

As we breathe in, we fill our lungs with air. This air is then moved up the windpipe (trachea) to the voice box (larynx). Normally, when we breathe in and out, our vocal cords stay open to allow air to flow freely into the lungs.

The vocal cords are two muscles covered in a delicate membrane. When the vocal cords are healthy, they appear as pearly white ‘V’ shape (see photo). When we breathe, the vocal cords are open and this allows air to flow in and out of the lungs.

Breathing: When we breathe the larynx is open. The vocal cords lie in a wide V shape to allow air to flow easily through them when you are breathing in and out.

Symptoms of Inducible Laryngeal Obstruction

The upper airway includes the larynx (voice box), vocal cords and muscles of the throat. ILO happens when muscles of the upper airway over react to a trigger, causing them to become uncoordinated and tight. The muscles of the throat squeeze together which can result in the vocal cords closing, when they should stay open for breathing.

This creates a partial narrowing or complete obstruction of the upper airway which stops air easily flowing in or out of your airway. This affects your ability to breathe comfortably as your upper airway is narrower or obstructed. You may experience breathlessness or your breathing can sound noisy or wheezy.
These symptoms and breathing difficulties are usually intermittent but can happen suddenly when exposed to a trigger. They typically only last for a short time and are reversible.

Symptoms vary in levels of severity. You may experience one symptom, or multiple symptoms, as follows:

ILO symptoms can be similar to other respiratory conditions, such as asthma or chronic cough. ILO can occur independently, or co-occur with these conditions.

However, there are fundamental differences between ILO and other respiratory conditions.

Key differences between Inducible Laryngeal Obstruction (ILO), asthma, and chronic cough. 

ILO has a sudden onset with throat tightness and difficulty breathing in, and inhalers usually don't help or worsen symptoms. Asthma develops over a few minutes, causing chest tightness and difficulty breathing out, but symptoms typically improve with inhalers. Chronic cough is defined by coughing for more than eight weeks, often accompanied by chest pain or tightness and shortness of breath; inhalers might be used to alleviate wheezing or shortness of breath in some cases.

It is important that you access specialist ENT and Respiratory assessment so that you are provided with an appropriate and correct diagnosis. Do not change or alter respiratory medication without consulting ENT, Respiratory medicine or your GP.

Causes of Inducible Laryngeal Obstruction

The precise cause of ILO is unclear. However, it is generally thought that ILO occurs because the throat becomes hypersensitive to a combination of different triggers, including physical, psychological or environmental factors.
 
Your throat is reacting to these triggers by closing the airway to protect the lungs from these irritants, affecting your ability to breathe.

It is important to explore and understand what may trigger ILO in you. If you are able to identify the underlying triggers, you can manage these to reduce the number of ILO episodes you may experience. This can improve your quality of life.

ILO can occur due to multiple triggers, including:
1.    External environmental triggers
2.    Physical triggers
3.    Emotional triggers

Common ILO triggers are discussed on our ILO causes, triggers and management section.