Vocal Fold Scar
What is vocal fold scar?
Scar refers to damage to the vibratory mechanism of the vocal fold. Vibration of the mucosa of the vocal fold depends on the integrity of the layers underneath it, particularly the superficial lamina propria, a loosely-packed network of fibers that functions like a ball-bearing layer to guarantee the mucosa on top of it is flexible and not tightly attached to the deeper tissues (see Normal Voice Function). Damage to this layer causes the covering of the vocal fold to be less pliable than it needs to be. Sometimes, scarring is severe enough to cause outright fixation of the mucosa to deeper tissues.
Scar usually results from surgery, and may be unavoidable, as when an invasive cancer must be removed, or may represent a complication. Scar may also result from damage to the larynx from disease or accident.
Figure 1: Scar is very difficult to show in still images. The bloodshot, unusually white vocal folds shown here are typical for diffuse scar, in this case after sloppy surgery for a pair of vocal fold polyps.
What are the symptoms of vocal fold scar?
Hoarseness results from abnormalities in vibration caused by scarring. The degree of hoarseness is roughly proportional to the extent and severity of the scar. When the mucosa does not vibrate readily, voice production requires more effort, and many people report soreness or tightness of their neck muscles as a result. In general, hoarseness from scarring becomes worse over the course of a day’s voice use, and a little better with voice rest. Scar does not usually cause difficulty swallowing or breathing.
What does vocal fold scar look like?
Because scarring causes disturbances in vibration, it is usually visible only on stroboscopy. Any laryngoscopy under normal light, whether with a flexible or rigid endoscope, cannot accurately assess scar. For this reason, scar is one of the most often overlooked problems in laryngology.
That having been said, certain features visible on a non-stroboscopic evaluation may suggest scar. These are due to the inflammation and excess deposition of fibrous tissue at the scar site, and include swelling, redness, and unusually large blood vessels leading into the area, or opacity and dullness of the normally shiny, translucent covering tissue of the vocal fold.
Figure 2: The vocal fold on the left of the image has a linear scar from an injury caused by the insertion of a breathing tube.
Figure 3: This patient has scar of both vocal folds after more than a dozen surgeries for papilloma.
How is vocal fold scar treated?
Every effort should be made to prevent scar from forming in the first place. Before surgery, this includes controlling acid reflux and eliminating smoking. After surgery, this includes voice rest and appropriate voice therapy to eliminate harmful vocal habits. During microlaryngoscopic surgery, the surgeon must use careful microscopic technique to avoid any unnecessary trauma to the superficial lamina propria and preserve all mucosa covering the vocal fold that is unaffected by the lesion.
Once a scar has developed, it should be treated nonsurgically for a period of time. Most scars will improve with voice therapy and judicious voice use. It is generally a good idea to let it do so for at least several weeks, until its characteristics stabilize over the course of a few examinations. This will minimize the amount of tissue that is involved.
Surgical intervention for scar must be considered carefully, for any such intervention stands to make scar worse. The challenge is to separate the mucosa layer from the tissues to which it is tethered and replace the damaged “pliability layer” (the superficial lamina propria) between them in order to keep them separated. There is no perfect substitute for superficial lamina propria available, although several groups are working to synthesize such a substance in the laboratory. Surgeons have tried a number of surrogates, including collagen, fat and a protein substance called hyaluronan with varying degrees of success. Often, the damaged tissues re-adhere despite the tissue placed between them, and sometimes to a greater extent than pre-operatively.
The rehabilitation of scarred vocal folds is one of the greatest clinical challenges in laryngology, and investigational efforts continue in a number of areas. Vocal fold scar is one of Dr. Sulica’s special interests, and is a focus of his practice.