Vocal Folds - Vocal Fold Wound Healing

Vocal Fold Wound Healing

Wound healing process is a natural regeneration process of dermal and epidermal tissue in which a series of biochemical events occurs in an organized sequence to restore the injuries. These events are complex and can be categorized into three stages: inflammation, proliferation and tissue remodeling. With respect to human vocal fold particularly, study about human vocal fold wound healing is not that extensive as investigations on animal models due to limited availability of human vocal fold. Vocal fold injuries can be caused by a variety of factors: chronic overuse of vocal, chemical, thermal and mechanical trauma such as over-smoking, laryngeal cancer and surgical operation. What’s more, some benign pathological phenomena like polyps, nodules and edema is another category of lesion which will definitely introduce disordered phonation.

Any injury to human vocal folds elicits a wound healing process characterized by disorganized collagen deposition and, eventually, formation of scar tissue. Verdolini and her group sought to detect and describe acute tissue response of injured rabbit VF model. They quantified the expression of two biochemical markers: Interleukin-1 and prostaglandine-E2, which are associated with acute wound healing. They found the secretions of these inflammatory mediators were significantly elevated when collected from injured VF versus normal VF. This result was consistent with their previous study about the function of IL-1 and PGE-2 in wound healing. Investigation about the temporal and magnitude of inflammatory response in VFs may benefit for elucidating subsequent pathological events in vocal fold wounding, which is good for clinician to develop therapeutic targets to minimize scar formation. In the proliferative phase of VFs wound healing, if the production of HA and collagen is not balanced, which means the HA level is lower than normal, the fibrosis of collagen cannot be regulated. Consequently, regenerative-type wound healing turns to be the formation of scar. Scarring may lead to the deformity of vocal fold edge, the disruption of LPs viscosity and stiffness. Patients suffering from vocal fold scar always complain about increased phonatory effort, vocal fatigue, breathlessness, dysphonia as well. Vocal fold scar is one of the most challenging problems for otolaryngologists because it’s hard to be diagnosed at germinal stage and the function necessity of VF is delicate.