A scar of the vocal fold is not quite the same thing as a scar elsewhere in the body. In voice production, the mucosa, or covering of the vocal fold, must vibrate over the underlying tissue. Underneath the mucosa is a special tissue layer, called Reinke’s layer, or the superficial lamina propria, that permits this. You can think of this as a ball-bearing layer that allows the free motion of overlying mucosa, while keeping it attached to the underlying muscle.
Any disruption of this layer is called a vocal fold scar. Scarring means that the mucosa is tethered to the underlying tissue and cannot vibrate freely. The resulting irregularities in vibration cause hoarseness, breathiness and demand increased effort to produce voice.
The sulcus on each vocal fold causes the mucosal cover to adhere to the deeper layers of tissue, resulting in poor mucosal wave vibration and incomplete glottal closure.
The sulcus on each vocal fold can be seen as a ridge running the length of the fold
Scar can occur in many ways. It can result from vocal fold lesions that have been present for a long time and grown into deeper tissue. It can result from generalized inflammation of the vocal folds, like a vocal fold hemorrhage or radiation used to treat cancer. It can also be an unintended consequence of surgery on the vocal folds. To a certain extent, scarring is unpredictable – it can happen even after the most meticulous surgery. But there are measures to take to minimize scar – voice rest after surgery, controlling laryngopharyngeal reflux (LPR), not irritating the vocal folds with cigarette smoke. The use of the laser for vocal fold surgery is another factor that may affect scar formation, because of the heat radiated by the laser beam. Prior to undergoing any vocal fold surgery, it’s important to speak to your surgeon about all of these factors, and especially about the use of the laser.
Sulcus vocalis is a special case of scarring in which the superficial lamina propria (or "ball-bearing layer") is absent over the length of the vocal fold. The reason for this is unclear. Theories include a genetic or developmental cause. There appears to be a higher incidence in certain ethnic groups.
Repairing scar once it has already happened is challenging. Simply separating the mucosa from the underlying tissue almost always results in the re-adhesion because the superficial lamina propria is still missing. There is no adequate replacement for the superficial lamina propria, although many substances have been tried. Synthetic tissue is under development, but not ready for clinical use. Substances that inhibit scar formation in other tissues exist, but their use in the vocal fold is experimental.
Voice therapy may make significant improvements in the voice of people with vocal cord scar, and especially in people with sulcus.