BREATHE EASY: Google CEO Larry Page suffers from bilateral vocal fold paralysis, which leaves him short of breath and weakens his voice. While Page plans to fund research to better treat this condition, new technologies are already in the works. Image: Courtesy of Google
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When Google CEO Larry Page blogged about his struggles speaking and, at times, breathing last week on his Google+ page he spotlighted a rare condition, bilateral vocal cord paralysis, which leaves sufferers short of breath and with few viable treatment options. This is likely to change in coming years. Page has deep pockets and has promised to fund research into the disorder via the Voice Health Institute. In the meantime scientists are experimenting with electrical stimulation technologies to enhance existing voice therapy as well as surgical treatments.
Vocal cord paralysis, or, more accurately, vocal fold paralysis (they’re not really “cords”) occurs when the nerve impulses to the larynx, or voice box, are interrupted. This can lead to paralysis of the vocal fold muscles on either side of the throat, impeding speech and even the ability to breathe. Because these folds protect a person’s airway from being choked by food, drink and saliva, bilateral paralysis—a rare variety that affects vocal folds on both sides of the larynx—can be life threatening.
Depending on the severity of the paralysis, patients can be treated using voice therapy, injections or surgery. In more extreme cases a patient might need a tracheotomy in order to continue breathing. New, experimental approaches to treating the condition seek to use electrical stimulation to move the vocal folds.
Electrical vocal fold stimulation faces two main challenges—it must stimulate the correct muscles, and has to achieve the right motion and correct vocalization, says Alexander Leonessa, an associate mechanical engineering professor at Virginia Polytechnic Institute and State University’s Center for Autonomous Systems. Leonessa leads a team of researchers who for the past few years have been experimenting with stimulators that, when placed on the neck, would generate electrical signals to activate the nerves governing vocal fold movement.
His latest approach involves designing a microcoil that could be implanted or injected into a patient’s neck, near the muscle that needs to be stimulated. That coil would interact with a larger coil placed around the neck—perhaps on a necklace—to generate a variable magnetic field that could generate the necessary electric stimulation. Leonessa’s team has used this approach in the lab to stimulate different levels of contraction in muscle removed from a mouse leg. This will help the researchers pinpoint specific muscles for stimulation and even stiffen the vocal fold to the necessary amounts to produce different sounds. The researchers are planning animal testing of their stimulator by the end of the year.
To learn more about vocal fold paralysis and its treatment, Scientific American spoke with Christy Ludlow, professor of communication sciences and disorders and director of James Madison University's Laboratory on Neural Bases of Communication and Swallowing.
[An edited transcript of the interview follows.]
What is vocal fold paralysis?
It means that the vocal folds are not moving. Normally we open our vocal folds to breathe and close them to speak or to swallow. When a vocal fold is paralyzed, it’s somewhat unpredictable what position it’s going to be in. A fold can be stuck in what’s known as the paramedian position, halfway between open and closed. When one side is paralyzed the person can have a breathy voice, as the condition typically affects the ability to close the larynx, which is important for speaking and swallowing.
If both vocal folds are in the paramedian position, you’ll have a weak voice, some reduction in your breathing capacity and some swallowing difficulties. If one fold is paralyzed to the side and the other is paralyzed in the center, then you’ll have a weak voice as well as breathing problems. If both vocal folds are paralyzed and sit [closed] in the midline [of the throat], such a closure can create a critical breathing problem, and that’s when someone may need a tracheotomy—to create an airway below the larynx—in order to be able to breathe. Often, to treat the breathing problem you have to sacrifice [a patient’s ability to speak].
What typically causes vocal fold paralysis?
There are different muscles that open and close the vocal folds. Both sets of muscles are controlled by what’s known as the recurrent laryngeal nerves. The left recurrent nerve is much longer than the right—it goes down and wraps around the aorta of the heart and comes back up along the tracheal esophageal groove. Because it is a longer nerve, the left side is more likely to be injured, for example, during heart surgery or a thyroidectomy—where the thyroid gland is removed due to cancer—or to be affected by aging or viral infections.
What type of viral infection might damage the vocal folds?
Although not common, a virus can be absorbed into the mucosa lining the upper respiratory area in the trachea, particularly in the larynx. The virus can be transported from the mucosa back through the nerve, causing inflammation and damage to the nerve. We don’t really understand which viruses do this; there’s a lot more research needed.
Could someone have genetic disposition toward vocal fold paralysis?