Vocal cord dysfunction (VCD) and exercise-induced laryngeal obstruction (EILO): Diagnosis

What are vocal cord dysfunction and exercise-induced laryngeal obstruction?

Vocal cord dysfunction is a condition where the vocal cords or nearby tissues in the voice box (larynx) close instead of opening during inhalation (breathing in). When symptoms mainly happen during physical activity or sports, it is called exercise-induced laryngeal obstruction. For an overview of the condition, including the signs and symptoms, please see Vocal cord dysfunction (VCD) and exercise-induced laryngeal obstruction (EILO): Overview.

How are VCD and EILO diagnosed?

Diagnosing VCD or EILO usually involves a combination of a detailed discussion of your child’s symptoms, a physical exam and diagnostic tests. Because VCD and EILO can look like other conditions—such as asthma, other lung problems or even heart issues—your child’s health-care provider may recommend testing to rule those out and help make the right diagnosis. However, not all these tests need to be performed in everyone.

Diagnostic tests include:

• spirometry (breathing test)
• challenge test (methacholine challenge or exercise challenge)
• laryngoscopy (a procedure used to view the vocal cords with a small camera called a laryngoscope)
• exercise test with laryngoscopy (for suspected EILO)
• other possible tests: blood tests, chest X-ray, electrocardiogram (ECG; a heart rhythm test), echocardiogram (ultrasound of the heart)

Your child’s health-care provider may also recommend recording a video of an episode. In some cases, video can be very helpful in identifying the characteristic features of VCD/EILO, such as stridor (high-pitched noise during inhalation).

Diagnostic tests for VDC

Spirometry

Spirometry is a breathing test used to check how well your child’s lungs are working. It measures how much air they can breathe in and out, and how quickly they can move that air. This test helps diagnose conditions such as asthma and other lung problems. The results of spirometry are usually normal in people with VCD and EILO if they are not having symptoms at the time of the test. In some cases, especially if your child is having symptoms, the test may show decreased air flowing into the lungs when they breathe in, which can be a clue that they may have VCD.

Laryngoscopy

Laryngoscopy is the most accurate way to diagnose VCD as it allows the health-care provider to see the vocal cords and structures in the larynx. This test is usually done by an ear, nose and throat (ENT) specialist. During this test, the ENT specialist uses a small, flexible tube with a camera (called a laryngoscope) that is gently passed through the nose to look at the back of the throat and the voice box. This test helps check how well your child’s vocal cords are moving when they breathe. It is a safe and common procedure.

If your child is not having an episode of VCD during the test, their vocal cords may look completely normal. For this reason, the health-care provider might try to bring on symptoms using one of your child’s triggers, such as exercise. Even if your child is not having symptoms at the time of testing, the test can still be important to rule out any structural problems in the voice box.

Diagnostic tests for EILO

To diagnose EILO, health-care providers may suggest a test to see how your child’s voice box is working while they are exercising. Here’s how it works:

• Your child will be asked to exercise on a stationary bike or treadmill, usually at the hospital or clinic.
• If they develop symptoms, a small flexible camera (laryngoscope) may be gently passed through the nose and positioned just above the vocal cords.
• This allows the health-care provider to watch how your child’s voice box moves while they breathe during exercise and document an episode of EILO.

Sometimes, the camera is only used at the end of exercise if your child’s symptoms are happening at that point. However, in some specialized centres around the world, the camera is placed before exercise and secured in place the whole time the child is exercising. This allows health-care providers to better see exactly when and how the vocal cords and other parts of the voice box are closing or collapsing. This test is called continuous laryngoscopy during exercise (CLE).

What if my child's symptoms do not happen during the test?

Since VCD and EILO symptoms come and go, it is possible that your child's symptoms may not be present during testing. In this situation, your child's health-care provider may still suggest treatment to see if symptoms improve. Even if testing does not confirm the diagnosis, your child's health-care provider can often have a good idea of what is going on based on symptoms and video recordings after ruling out other problems.