One of the most interesting experiences for singers in the laryngologist’s office is to see their larynx on the video monitor screen. As you phonate, the vocal folds open and close; as you glissando up, the vocal folds elongate and thin out. No matter how often our patients see this, it never loses its visual impact.
Not infrequently, we see patients who are concerned about how well the vocal folds move. They may have been told by another physician that they have a “lazy vocal fold,” or that there is a weakness in one of the folds. What is this, what causes it, and what does it mean for the singer?
Let’s step back for a moment from singing and generally consider the movement of the vocal folds. Normally, the vocal folds are constantly moving, whether we speak, sing, rest, or just breathe. They move themselves, using muscles within the vocal folds (vocalis) and are moved by muscles attached to them via the laryngeal cartilages (the various cricoarytenoid, interarytenoid, and cricothyroid muscles).
Speaking of “lazy,” we have all become a bit lazy in how we describe vocal fold movement. To be semantically correct, vocal folds should be characterized as motile (capable of active movement) as well as mobile (capable of being moved passively). In addition to movement caused by muscles within the vocal folds and attached to the laryngeal cartilages, vocal folds also sway in the breeze as air rushes between them during inspiration and expiration. They also reflexively approximate to build up intrathoracic pressure, whether for a cough, sneeze, lift, push, or even just to initiate a whistle. This is why vocal folds are never completely immobile, no matter how strict your vocal rest regimen may be. It is theoretically possible for a vocal fold to be completely immobile under specific pathologic conditions, but in most cases there is movement, active and passive, that accompanies our everyday lives.
Not only do vocal folds move constantly, they do so in a generally symmetrical fashion: each side is a mirror image of its counterpart in terms of pulling apart (abduction), coming together (adduction), the degree of excursion, the rapidity of movement, and its static position and vertical level within the larynx. I say “generally” for a reason. While the body is generally symmetrical on either side of its vertical axis, it really isn’t absolutely identical. We all have one foot that is bigger, one eye that is stronger, one side of the mouth that we prefer chewing on, and so on.
Similarly with the larynx, there may be minute differences in both the shape, surface features, and positioning of the two vocal folds. For example, it is not uncommon to see one arytenoid cartilage tilt and tip a bit across the midline as the vocal folds approximate.
These minute visual differences are normal, and should not be alarming. But what about movement?
We can look at vocal fold movement with the naked eye and the stroboscope. This device takes samples of vocal fold position at regular intervals. These tiny snapshots are strung together and create the illusion of movement, much as tiny still pictures on a movie film are played back. While a stroboscope does not display every single movement of the larynx, it is a good way to identify significant differences in movement between the two sides. One vocal fold may not move as freely as the other or it may vibrate in an aperiodic fashion (i.e., not vibrate regularly at the pitch that the singer is trying to hit).
While a strobe is a great way to look for microscopic movement and stiffness, it is not the way to look at gross abduction and adduction. These larger movements, which are made when you prepare to sing or to take a deep breath, are necessarily assessed with the naked eye. Some studies have quantified the degree of excursion by drawing lines on still photos of the larynx—but the degree, and especially the speed of adduction or abduction remains, at least in the examination room, a matter of clinical judgment. So one doctor’s “lazy cord” may well be another doctor’s “normal variant”!
But the story is not simply one of clinical judgment. There are situations where one vocal fold may become temporarily and partially impaired. In otherwise healthy younger patients, we usually attribute this to a viral infection. The true incidence of this condition is unknown, for two reasons. Often it is mild and does not cause any symptoms. In other cases, it can temporarily cause vocal impairment, but the patient doesn’t see a doctor and the condition resolves on its own. In either case, it is never diagnosed.
So it may well be the case that on one examination the laryngologist sees some impaired movement in one vocal fold, and two weeks later the condition has resolved and another laryngologist sees nothing. In this situation, both diagnoses are correct.
From a practical point of view, here are the “take-aways” for singers. The occasional finding of minor asymmetry in vocal fold movement can be a normal variant, with no impact on the voice. When the asymmetry causes vocal problems and the doctor identifies a “lazy cord,” remember that this may be a temporary viral problem that can resolve completely; a second and third examination is in order, over the next few months. Even in cases where the slight weakness persists, your larynx, an organ with a remarkable bag of tricks up its sleeve, can learn to compensate and return you to your normal voice. However, where the weakness causes persistent vocal problems, recurs, or worsens, medical help should be sought.
