Inducible Laryngeal Obstruction (ILO)

Keoghs has a long history of dealing with legacy claims. Our team of over 130 specialists operates across the UK, acting for the major legacy insurers, as well as large corporate and public sector bodies.

Our work involves a wide range of diseases and while most of it deals with the volume of claims arising from asbestos-related diseases (NIHL, WRULD, HAVS, dermatitis and asthma), we also handle more unique and unusual maladies.

One recent case that was initially made as a claim for occupational asthma due to exposure at work turned out to be Inducible Laryngeal Obstruction. Our specialist occupational disease handler had not encountered a claim for this condition in over 30 years of practice.

What is Inducible Laryngeal Obstruction (ILO)?

The condition was first identified in 1869 and associated with patients diagnosed as ‘hysteric’ as it was long thought to arise from a psychological disposition.

The term ILO was adopted in 2013 by the European Respiratory Society, who refer to the condition as ‘an inappropriate, transient, reversible narrowing of the larynx in response to external triggers’.1

It is a throat disorder where the vocal cords close inappropriately during breathing, resulting in an obstruction in the airways that causes breathing difficulties.

One confounding factor is that ILO not only mimics asthma but can arise alongside it, making a differential diagnosis very difficult, thus ILO is easy to miss.

What are the symptoms?

The symptoms of an ILO trigger are like those of asthma. They can vary between individuals and include difficulty to breathe and sometimes a feeling of choking and being unable to breathe. There can be audible sounds when breathing and ILO can induce anxiety or panic.

Other symptoms can include coughing, chest tightness, voice change/loss of voice, choking or swallowing issues, or the sensation of a lump in the throat.

The condition is not life-threatening. In the most extreme cases a person may lose consciousness for a few seconds.

What causes it?

The exact cause and underlying mechanism of ILO is not known, and no organic cause has been identified.

This makes it difficult for a claimant trying to establish a cause for their condition and determining whether this it is constitutional or was caused by any exposure at work.

This is important in a legal claim for understanding whether a negligent exposure has caused a claimant to develop ILO (with all the consequential difficulties arising from that) or only triggered an ILO episode which is short and transient.

However, once ILO has been identified, the correlation between a trigger and the onset of an ILO episode is easier to establish. The most common triggers of ILO are exercise, irritant exposures, and emotional stress.

Other less common triggers reported have included catching a cold or viral infection, eating crumbly, dry or cold foods, and the acts of laughing, coughing or even talking.

This can make identifying the actual cause and whether the trigger is a substance at work (which may lead to a claim) or at home, or due to an exercise regime or emotional stress, very difficult.

As with many occupational disease claims, a detailed history of the alleged exposure or trigger and the onset of symptoms will be vital, and consideration of the following will assist:

• A detailed record of the potential irritant smoke, fume, vapour or dust triggers, both at work and home, and a correlation with triggered symptoms will help.
• Consideration of other potential triggers, such as exercise or emotional stressors.
• Investigations, such as laboratory provocation studies with controlled exercise tests, may assist.

In the trigger is identified, it is easier to consider the source of the trigger and whether there has been a negligent exposure to it in the workplace.

What is the prognosis and what treatments are available?

Where an irritant is identified then removing the individual from the trigger will often help, although the irritant may be common, such as bleach, and provoke an episode in places such as supermarkets, which raises issues with avoiding the trigger irritant.

Many medical treatments comprise a mix of coping mechanisms, ranging from avoidance of the irritant, psychotherapy, behavioural modifications and distraction techniques, and common breathing techniques to move focus away from the larynx during a triggered ILO event.

There are medicines available, including antidepressants and drugs that dilate the airways, which have been known to relieve symptoms.

Summary

ILO is a poorly understood condition, which is often misdiagnosed as asthma. As the joint European Respiratory Society and European Laryngological Society observes: ‘many aspects of ILO remains at a relatively embryonic stage’.1

This poorly understood condition makes determination of diagnosis, causation and prognosis as well as treatment, difficult to determine in both medical and legal terms.

Top claims handling tips to consider:

• Is the claim advanced for causing the ILO or a trigger of the ILO? Check carefully any literature stating that the workplace exposure has caused the ILO rather than triggered an episode.
• What is the alleged trigger and correlation with symptoms? Consider references in the medical records.
• Are there other potential triggers, such as exposure to the irritant outside work (e.g. household bleach/cleaner or a varnish used at home), exercise or emotional stress?
• What legal duties arise as to control of the alleged trigger irritant and have they been complied with? Some irritants may not be hazardous substances that require special controls.
• If no specific controls were needed, was the trigger of an ILO foreseeable and one that could not have been prevented?
• The diagnosis and whether you want your own medical expert to consider diagnosis, causation and prognosis?

At Keoghs we are both happy and able to listen and help you with both well-known and unusual disease claims.  

1 European Respiratory Journal 2017 (VOL 50 Issue 3)