By Doug Kaufman, MD Consult, March 21, 2007

Vocal cord dysfunction (VCD), in which the vocal cords close and restrict breathing, can be difficult to diagnose.

"Most people, when they hear about people with trouble with breathing—wheezing or stridor—would consider that asthma," said Dr John Seibert, an otolaryngologist at Barnes-Jewish Hospital in St Louis. "Asthma is so frequent, especially in adolescents today, that it seems to be the more common diagnosis. ... The problem is, these patients will present with the same symptoms of cough, respiratory distress—these acute episodes which are thought to be an exacerbation of asthma."

Often, these patients are seen by primary care physicians or pulmonologists, Dr Seibert said, so no one really gets a good look at their vocal cords.

"More times than not, we''re relying more on their history, what is going on while these episodes are occurring and how many times this is occurring with the patient," said Dr Seibert, who is also an assistant professor at Washington University School of Medicine in St Louis.

Clinically, VCD remains an underrecognized disorder in many cases, according to Mason: Murray & Nadel''s Textbook of Respiratory Medicine, 4th edition. Many patients are misdiagnosed as asthmatics for years and develop iatrogenic complications related to steroid therapy, which does not provide significant benefit, according to the book. This adds to the psychological dimensions of this problem.

Many [VCD] patients are misdiagnosed as asthmatics for years and develop iatrogenic complications related to steroid therapy, which does not provide significant benefit.

In "Understanding Vocal Cord Dysfunction: A Step in the Right Direction With a Long Road Ahead," an editorial in the April 2006 issue of Chest, Kent L. Christopher, MD, FCCP, explained why it remains difficult to understand and diagnose VCD.

"The first answers are obvious," he wrote. "(1) [I]t is a relatively uncommon condition; (2) the disorder closely mimics asthma; (3) intermittent symptoms make endoscopic confirmation logistically difficult; and (4) by the very nature of a somatoform disorder, diagnosis of the condition is elusive."

VCD tends to affect more women than men, with the majority of patients in the 20- to 40-years age range, Dr Seibert said.

"A lot of times they won''t have symptoms, but if you look into the larynx with a fiber-optic scope, you will see some edema of the cords themselves, or the area behind the cords, which is called the postcrichoid area," he said. "If we see some edema there, that suggests they have some reflux."

Reflux doesn''t always cause VCD, but it can be a precipitating factor, Dr Seibert said. Experts think VCD is related to hypersensitivity caused by the vagus nerve, he added. The hypersensitivity causes the cords to close down.

"[Patients] can''t breathe, they can''t talk, and it causes [a reaction] like an asthma event," he said.

To diagnose VCD, doctors first look at the patient''s medical history, Dr Seibert said. To rule out asthma, doctors can check peak flow and lung function. But the typical curves that indicate an obstruction are still tough to detect.

"The only way they would show an obstructive curve is if they were having an acute episode at the time," he said. "More than likely the patients who have vocal cord dysfunction will have a normal peak flow. So if a [physician] sees a normal peak flow, but still sees these recurrent episodes, not responding to medical therapy, then that could suggest the possibility of vocal cord dysfunction. Again, it''s one of those things where you really have to rule out other things first."

One method of distinguishing between asthma and VCD, Dr Seibert said, is to give the patient a pulmonary function test using methacholine to induce irritation. Asthma patients will have hyperresponsiveness, while people with VCD will show no hypersensitivity.

There are symptoms to watch for.

"When episodes are occurring, [patients] may have these harsh, high-pitched stridor sounds, but that goes away after their cords relax," Dr Seibert said. "Again, that could sound just like asthma."

VCD can be associated with reflux that irritates the larynx, causing postnasal drip and chronic sinusitis. Inhalers and bronchodilators, typically administered with a misdiagnosis of asthma, just don''t work. Speech therapy and relaxation techniques aimed at naturally opening the vocal cords can be effective. The therapy is aimed at helping people with VCD "learn to control the spasms they''re having," he said.

Training patients to listen to their bodies helps.

"They basically use biofeedback to help realize, ''OK, here''s my larynx clamping down. I need to relax. This will pass,''" he said.

Athletes, by the nature of their pursuits, may be more susceptible than non-athletes.

"You may see it more in athletes, possibly, because those are the ones who are doing the more strenuous exercise, they''re pushing themselves more to the limit and there''s a possibility of having a greater irritation in that area," Dr Seibert said.

While VCD is not a frequent occurrence, doctors should be aware of its symptoms and how it differs from asthma.

"It''s something we should keep in the back of our minds [as a possibility]," he said. "There have been some studies that have looked at this and [found] that somewhere around 10% to 15% of patients going to get asthma referrals [because] they were unresponsive to therapy did have VCD."

Treating asthma is a good first step, he said. But if symptoms haven''t improved in 2 to 3 months, it''s time to refer the patient to an otolaryngologist.

"Pulmonologists do a very good job ... with asthma," Dr Seibert said. "... But [VCD] is more in our realm, in the larynx, and we''re able to visualize that. We look at this daily, and we can see if there is any sort of dysfunction going on."