In this age of increasing reliance on diagnostic technologies to better see pathologies of the body, there is a confounding problem of seeing too much, with too little understanding of what one is seeing and whether what one sees poses a problem.
Explore This IssueApril 2009
In the world of laryngology, vocal fold paresis falls into this diagnostic problem area. With the aid of electrophysiological investigations, vocal fold paresis (or partial or incomplete paralysis) is now a recognized clinical condition that is seen as belonging on a continuum of neurogenic dysfunction along with vocal fold paralysis. Although vocal fold paralysis was once thought to be an all-or-nothing phenomenon, as noted by Lucian Sulica, MD, in a recent review article (Curr Opin Otolaryngol Head Neck Surg 2007;15:159-62), improved diagnostics have now shown that there are variable degrees of nerve function of the vocal folds. What distinguishes vocal fold paresis from vocal fold paralysis is both the degree of nerve dysfunction and mobility of the vocal folds.
According to Dr. Sulica, Associate Professor in the Department of Otorhinolaryngology at Weill Cornell Medical College in New York, who moderated a miniseminar on this topic at the 2008 annual meeting of the American Academy of Otolaryngology-Head and Neck Surgery, vocal folds in patients with vocal fold paralysis may still demonstrate some evidence of nerve function, but the vocal fold is completely immobile. In patients with vocal fold paresis, the vocal folds themselves retain substantial mobility, he said, but the muscles of the vocal fold in these patients receive incomplete motor nerve input.
Despite this recognition that vocal fold paresis exists, there remains the problem of meaning. Part of this is the lack of agreement on an exact definition of what vocal fold paresis is, and its natural history. Part of this is the real thorny problem of distinguishing what is normal from what is pathology on laryngeal examination.
How to Determine the Meaning of What Is Seen
Diagnosis of vocal fold paresis is done by identifying the one vocal fold that does not move as well as the other, according to Mark S. Courey, MD, Director of the Division of Laryngology at the University of California, San Francisco. However, no one’s larynx is totally symmetric at baseline, he said. Therefore, the big trick is to determine if the asymmetric movement is due to a true nerve injury or just a congenitally asymmetric larynx.
Put another way, although laryngeal examination may show asymmetric movement of the vocal folds, determining whether this is a problem is not easy.
When you figure that there are frequently asymmetries in laryngeal motion in the normal larynx, said Dr. Sulica, you begin to appreciate the difficulty in deciding whether a given finding is paresis or not.
Electromyography (EMG) is the only objective way to diagnosis vocal fold paresis, according to Dr. Sulica, and even with the use of this diagnostic tool, mild cases of paresis may be difficult to diagnose. Likening the ability of laryngoscopy to show small asymmetries that are not significant to the ability of electromyography to show nonsignificant small aberrations, Dr. Sulica emphasized that any hypotheses based on the current understanding of paresis are still based on very subjective findings and that more solid evidence is needed to discern which findings are meaningful.
It would be regrettable if vocal fold paresis became the new reflux, he said. Many symptoms that we can’t explain tend to be attributed to laryngopharyngeal reflux without a great deal of critical thinking.
Albert L. Merati, MD, Chief of Laryngology Service in the Department of Otolaryngology-Head and Neck Surgery at the University of Washington Medical Center in Seattle, believes, however, that the majority of laryngeal asymmetries in symptomatic patients are related to changes in the neurologic functioning of the larynx and therefore indicative of paresis. He bases this assertion on a few small studies that reviewed EMG findings in paresis patients (J Voice 2006;20:269-81; Am J Otolaryngol 2006;27:106-8).
His advice to otolaryngologists is to trust their endoscopy. If your patient has a symptom related to the vocal folds and you see an asymmetry by your examination, it is probably real, he said. The real question is what significance does this finding have?
Common symptoms of vocal fold paresis include mild hoarseness, increased phonatory effort, and limitation of pitch-all of which can get more pronounced when a person tries to project his or her voice, or after heavy voice use. Signs include loss of vocal range, soft voice, inability to project the voice, increased vocal roughness, and, sometimes, swallowing problems.
Emphasizing that these are the main symptoms of paresis of the motor nerves, Dr. Sulica also mentioned that other symptoms such as cough, throat clearing, and laryngospasm may indicate the less-explored condition of paresis of the sensory nerves.
Dr. Sulica, however, takes a more cautious approach to diagnosis and emphasizes the need for consistency among the symptoms and signs of paresis with the clinical history of the patient, and recommends electromyography to confirm the clinical suspicion of paresis. I understand very well that these aspects are not always in perfect agreement, he said, so there’s a role for clinical judgment as well.
Caution is also the preferred approach by Dr. Courey, who thinks that physicians too often diagnose vocal fold paresis based only on symptoms, even when the symptoms are nonspecific. This may cause the patient to give up on improving the way they use their voice through behavioral therapy, because the patients feel that they have a neurological problem rather than that they are just inefficient laryngeal users, he said. If they could learn to use their voices better, it would probably serve them better.
Significance of What Is Seen: Whether to Treat
Whether to treat vocal fold paresis may be largely up to the patient, whereas how to treat may be linked more to the proclivities of the physician they see. For Dr. Merati, treatment is driven by the particular needs of the person experiencing the voice changes and is not always warranted.
But for those patients in whom even slight changes are problematic, treatment by injecting the vocal folds with a substance such as collagen offers an easy way to correct the condition.
For Dr. Merati, this ability to treat people in the office with simple injections, married to the recognition that even slight paresis can be a problem, has resulted in a lowered threshold for treating this condition.
People coming into the office complaining of vocal fatigue 10 years ago probably wouldn’t be getting treated for the same things they are getting treated for today, he said. The threshold for treatment has been lowered, and more people are being helped.
Dr. Sulica agreed that office-based injections are able to correct the vocal folds for paresis resulting in incomplete vocal fold closure, but emphasized that treatment is evolving. In some cases, like vocal fold paralysis, the paresis corrects itself over time, whereas in other cases, patients can compensate for the paresis with the remaining neuromotor function that is intact.
Favoring a more conservative approach, Dr. Courey emphasized the need to first help patients learn to function with limited vocal fold motion by teaching them to change the way they produce their voice to fit their laryngeal mechanism. He recommends surgery and injection to reposition the vocal fold only if this fails.
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