Vocal cord dysfunction (VCD) is also known as paradoxical vocal fold motion (PVFM) and, for those with symptoms limited to exercise, exercise-induced laryngeal obstruction (EILO). It causes shortness of breath which can be very severe.
VCD and EILO are important conditions, because they are frequently misdiagnosed as asthma, and they can cause profound changes in quality of life.
Normal and Abnormal Vocal Cord Function
To understand VCD and EILO, it is helpful to understand how the vocal cords function. The vocal cords are located at the top of the windpipe (trachea) and vibrate to produce noise and voice. Breathing causes the vocal cords to open, allowing air to flow through the windpipe (trachea) and into the lungs. During episodes of VCD or EILO, the vocal cords constrict partially or near completely. This leaves a restricted opening for air to flow through the windpipe and causes shortness of breath.
Vocal cord dysfunction is different from vocal cord paralysis. They are different conditions requiring different treatment.
History of VCD & EILO
VCD and EILO were discovered relatively recently. Some descriptions of possible cases first appeared in medical literature in 1842 and then again in 1951, both times inaccurately characterized as having factitious (self-created) symptoms.
In 1983, a group of people who were said to have "uncontrolled asthma" were seen at National Jewish Health for evaluation. A multidisciplinary team of medical professionals, including pulmonologists, otolaryngologists, psychiatrists and speech-language pathologists, was able to accurately identify the condition and provided treatment for what we now know as VCD. Their findings were published in the New England Journal of Medicine in 1983.
People with symptoms limited to exercise were described in the years that followed. Since the 1980s, we have come to realize that they do not share all of the features seen in the first group described in 1983.