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.
Swelling (2 of 4)
Pre-phonatory instant. Standard light shows only the suggestion of margin swelling, as the dark space between the cords is not exactly the same along its length.
Swelling (3 of 4)
Open phase of vibration. Strobe light shows both wide excursions (indicating mild flaccidity) and margin swellings.
Pre-phonatory (1 of 4)
Pre-phonatory instant at E-flat 5 (622 Hz), conventional view with standard illumination shows no evident mucosal disorder.
Phonation 2 of 4)
Phonation, at E-flat 5 standard illumination, with vibratory blur and still no visible problem.
Subtle swellings (3 of 4)
Only at very high pitch and with high magnification can one see subtle swellings. Here, closed phase of vibration at C# 6 (1106 Hz).
Indicator swellings (4 of 4)
Open phase of vibration, also at C# 6 . Given the patient’s unimpaired “swelling checks,” these findings serve only as an indicator of past and potential over-use of voice, and should not be explained to the patient as being evidence of past problem and potential future problem if over-use again occurs, but, if voice is functioning well, not necessarily as a current problem.
Breathy voice (1 of 6)
Distant view at the prephonatory instant in young female singer. There is a wide gap between the cords. The explanation for this gap is not immediately evident, but the voice is breathy.
Phonation (2 of 6)
Phonation has started with margin blurring, and the sense of extra space between the cords remains.
Closed phase (4 of 6)
Closed phase of vibration, still at B4. Note the incomplete closure posteriorly caused by MTD. Arrows indicate the vocal processes.
Open phase, indicator lesions (5 of 6)
Open phase of vibration, strobe light, at F#5 (740 Hz). Here, the subtle indicator lesions are seen more clearly; vocal cord margins are not perfectly straight.
"Closed" phase, MTD (6 of 6)
“Closed” phase of vibration is not really closed and the vocal processes do not come into full closure, again consistent with MTD.
Breathing position (1 of 4)
Young woman with singing voice complaints. Speaking voice is normal but swelling checks are strongly impaired. Here, breathing position, standard light, nothing is very noticeable except subtle elevation left vocal cord (right of photo).
Phonation (2 of 4)
Here, high pitch but under standard light and with only moderate magnification, the abnormality is still fairly unimpressive.
Obvious swellings, open phase (3 of 4)
At closer range, using strobe light, and at the same time using fairly high voice (F#5 740 Hz), the obvious margin swellings are seen.
Obvious swellings, closed phase (4 of 4)
Same pitch, closed phase of vibration. Now both vocal and visual findings are indeed obvious. After a trial of speech therapy, vocal cord microsurgery provided return of "original equipment" vocal capabilities.