Mucosal edema or swelling is the build-up of edema (tissue fluid) within the mucosa, the layer of tissue that lines the body’s interior. In the larynx, this build-up of edema usually occurs at the mid-point of the vocal cords, as the body’s response to vocal overuse, and it resembles a small, low-profile blister.
Vocal overuse triggers this build-up of edema because, with vocal overuse, the vocal cords undergo more vibratory stress and trauma than they are designed to handle. The body responds by gathering edema to form a protective cushion. However, this swelling distorts the vocal cord’s shape and can limit its flexibility, which can thereby impair the voice, making it sound acutely husky or hoarse.
From mucosal edema to nodules:
If the voice is rested even moderately, this edema fluid will disperse rapidly—within 12 to 24 hours if not severe—so that the swelling vanishes and the voice returns to normal. However, if the voice continues to be overused, then the body may build up more chronic swelling materials (no longer just edema), so that the vocal cords develop nodules.