This common condition is often misdiagnosed as a respiratory or cardiac issue, but new diagnostic tools and treatments could change that.
Breathlessness is not always a respiratory or cardiac issue but may be a sign of vocal cord dysfunction, says an Australian expert.
Vocal cord dysfunction is common. In addition, there are new ways to diagnose it and treatment is effective, Professor Philip Bardin, director of Lung and Sleep Medicine at Monash University told ASCIA conference goers in Melbourne this month.
“There are about half a million patients with vocal cord dysfunction, some of whom may be floating around your practices,” he said.
“It’s a real clinical entity that’s been hiding under our noses and it’s moving toward prime time at last.”
WHAT IS VOCAL CORD DYSFUNCTION?
Vocal cord dysfunction, also known as Inspiratory Laryngeal Obstruction, is characterised by inspiratory closure, rather than opening, of the vocal cords.
The symptoms can look a lot like asthma – cough, tightness of the throat, breathlessness, and stridor. But, unlike asthma, there is a change in the voice. An episode is often, but not always, brought on by triggers such as smells, cleaning products, deodorants, or vigorous exercise.
The condition also frequently co-exists with asthma. A 1995 US study showed that almost 60% of those with vocal cord dysfunction had asthma. A 2010 study reported around 40% of those with severe asthma and almost 30% of those with any asthma had vocal cord dysfunction. The condition can cause exercise-induced breathlessness. It can even mimic covid vaccination anaphylaxis.
If left untreated, it leads to a cycle of breathlessness, anxiety, dysfunctional breathing and chronic activation of laryngeal reflexes.
“There are patients where there is no clear explanation for their breathlessness,” said Professor Bardin. “It’s usually swept under the carpet. The patient is told, ‘It must be your asthma’.”
Vocal cord dysfunction is a heterogenous condition with at least four phenotypes – “an important insight belatedly arrived at,” said Professor Bardin – and they look quite different to each other.
A patient with classic vocal cord dysfunction will have some anxiety and other comorbidities, is breathless, and has no evidence of asthma or other structural lung disease.
Lung associated vocal cord dysfunction is seen in people with asthma and commonly in those with COPD and other lung diseases.
Exercise induced dysfunction is mostly seen in young people during exercise. And the fourth is incident-related vocal cord dysfunction.
“That has important implications for allergy,” said Professor Bardin.
For instance, some people who had been given a covid vaccine prior to throat symptoms were found to have vocal cord dysfunction rather than anaphylaxis.
MAKING DIAGNOSIS EASIER
“Diagnosis can be quite tricky, but the classic symptoms are worth looking at,” said Professor Bardin.
These include breathlessness with a history of or symptoms of a tight throat and also tightness of the chest, particularly if they have asthma.
“And then the other classic abnormality is that the voice changes during these episodes of breathlessness. They become croaky. They can’t speak sometimes, whereas in asthma most patients, unless they’re really breathless, can actually speak fairly normally. It’s only if they’re really distressed that their voice is affected,” he said.
The gold standard for diagnosis is laryngoscopy, generally done by ENT surgeons.
“But laryngoscopy, even in Australia, is not freely available. Patients have to wait. And if it’s not done by an expert, you can get a false positive, so it is a test that has drawbacks,” said Professor Bardin.
Another good option for patients over the age of 21 is a dynamic CT of the larynx, a non-contrast scan that takes about a minute, which will show narrowing of the larynx during inspiration and is shown to be reliable.
“Every large hospital in Australia has a cardiac CT, so there’s widespread availability. We’ve adapted it to look at the larynx. It scans an area of about 16cm, which is perfect, from the larynx to the thoracic inlet and it’s possible to see the narrowing of the larynx during inspiration,” said Professor Bardin.
“The patient says, ‘it feels like breathing through a straw’, and the picture shows that.”
A negative result does not necessarily rule out vocal cord dysfunction, because the condition is intermittent, so retesting might be necessary. Sometimes the provocation, if there is one, works quite well, said Professor Bardin. “And sometimes nothing happens. Patients will often say, ‘today I’m quite well’. And that’s another difficulty of its intermittent nature. Now you see it, now you don’t.”
Exercise-induced vocal cord dysfunction can be diagnosed using bespoke headgear.
Studies haven’t been done in children, Professor Bardin noted, partly because of the difficulty in imaging, but the impression was that it was more common in adults.
MANAGEMENT
Standard treatment, which is speech therapy for laryngeal retraining, is “very effective,” and also reduces subsequent healthcare need significantly, said Professor Bardin.
“Using speech therapy combined with a multidisciplinary team approach [including a respiratory physician, Ear-Nose-Throat surgeon, nurse specialist, respiratory scientist, and speech pathologist] we were able in our patients to reduce healthcare, either GP visits or emergency department hospital admission, by at least 50%,” he said.
In the same group, steroid use was also halved.
If speech therapy fails, the alternative treatment is botulinum toxin injection, which has similarly good results, said Professor Bardin.
“This is a very common condition, and it’s been happening without us really knowing and understanding that it’s taking place. The condition is treatable, and there are very effective approaches and interventions,” he said.
