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Diagnosis of Vocal Fold Scarring
How is vocal fold scarring diagnosed?
An otolaryngologist can make a diagnosis of vocal fold scar from a
patient history and a laryngeal examination. If vocal fold scarring is
suspected after a review of the patient's voice symptoms, the
otolaryngologist will examine the voice and voice box to confirm
diagnosis.
Patients with vocal fold scarring will typically have a roughness,
breathiness, or weakness to the voice. Often, a strained sound is
associated with vocal fold scarring.
The physician will also note whether a patient is attempting to
compensate for or adapt to vocal fold scarring by speaking in an
unnaturally low pitch or high pitch ("compensated falsetto").
Stroboscopy Is Key Diagnostic Test
The most important method to diagnose vocal fold scarring is
stroboscopy. Stroboscopy allows the examiner to observe vocal fold
vibration in "slow motion" during voice production. From this
observation, the nature of the vocal fold vibration, specifically the
mucosal wave, can be observed. (For more information, see Laryngoscopy/Stroboscopy.)
- Stroboscopy reveals the movement of the vibrating
layer that occurs during vocal fold vibration. Stroboscopy combines
laryngoscopy with synchronized rapid light pulses, thus providing a
slow motion-like view of vocal fold vibration.
- In reality,
vocal fold vibration is extremely fast. Stroboscopy is necessary to
create a slow motion-like, simulated view of vocal fold vibration. This
view is referred to as the mucosal wave. (Note: The vocal folds are not
really slowed down, rather the strobe light provides a simulated
slow-motion-like picture of the different phases of the vibratory
cycle.) (For more information, see Anatomy & Physiology of Voice Production.)
- The
mucosal wave is changed when vocal fold scarring is present. Normally,
the mucosal wave is rapid and regular and with good reach in its
movement (amplitude). Vocal fold scar causes the mucosal wave to be irregular and/or reduced in both speed and extent of movement (amplitude).
Typical Findings in Vocal Fold Scarring
Typical findings from stroboscopy in patients with vocal fold scar include:
- Decrease in the extent of movement (amplitude) of the mucosal wave seen during vocal fold vibration
- Abnormality of vocal fold closure during vocal fold vibration
- Decreased or stiffened appearance of mucosal wave
- Incomplete vocal fold closure or a shortened duration of closure
Incomplete vocal fold closure is an extremely important diagnostic
finding because it directly indicates vocal fold scarring and
correlates with the breathiness and increased effort that is commonly
experienced by patients with vocal fold scarring.
How Vocal Fold Scarring – No Matter How Small – Can Hamper the Vibratory Cycle
| Normal |
1 Column of air pressure moves upward towards vocal folds in "closed" position
2, 3 Column of air pressure opens bottom of vibrating layers  of vocal folds; body of vocal folds stays in place 
4, 5 Column of air pressure continues to move upward, now towards the top of vocal folds, and opens the top |
(click for larger image) |
6-10 The low pressure created behind the fast-moving air column produces a
Bernoulli effect which causes the bottom to close, followed by the top
10 Closure of the vocal folds cuts off the air column and releases a pulse of air.
New vibratory cycle – repeat 1-10. |
Abnormal Vocal Fold Scarring –
Impact on Opening and Closing During Vibratory Cycle |
2 Stiffness from Scar  increases amount of air pressure needed to open vocal folds
hoarseness, increased voice effort, voice fatigue |
(click for larger image) |
8 Stiffness from Scar decreases Bernoulli effect's efficiency to close vocal fold
hoarseness, breathy voice |
Although quite simplified, this is a schematic representation of what could go wrong when one has scarred vocal folds.
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Scarring
affects the vibration of the vocal folds making it harder to open
(panel 2) and harder to close (panel 8) compared to normal vocal folds
(see normal vocal fold parallel diagram). Hence, patients with
scarring in one or both vocal folds usually complain of increased
effort and therefore voice fatigue. Depending on severity of scarring,
the voice may be hoarse all the time, or just when added inflammation
occurs as when one has a cold or reflux laryngitis. Also, when a cold
goes away, the hoarseness that was precipitated by the cold does not go
away when the cold lifts because the scarred area would be expected to
heal slower if not worsen with each inflammatory insult.
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Panel
2 also depicts the increased air pressure needed to open a scarred
vocal fold and the asymmetry in vibration (cycles of opening-closing)
when one fold is stiffer (the scarred vocal fold) than the normal vocal
fold. This would be reflected in a change of voice quality that would
be more noticeable on singing. Worse scar leads to worse voice changes.
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Scarring
at the inferior (bottom) edge of the closing (striking) surface of the
vocal folds is harder to detect. Usually the superior (top) edge of the
closing surface can and will compensate.
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With increasing scar extent or severity, loss of vocal fold
pliability increases, thus hampering additional phases of the vibratory
cycle – and resulting in more severe voice symptoms.
Extent of Vocal Fold Scar
- Focal vocal fold scar: Scarring that involves a small portion of one or two of the vocal folds
- Full-length vocal fold scar: Scarring that extends the length of one or both of the vocal folds, depending upon the severity of the condition
Stroboscopy can also detect vocal fold lesions, such as cysts or
polyps, that may or may not be associated with the presence of vocal
fold scar. (For more information, see Vocal Fold Lesions.)
 Key Information
Key Role of Stroboscopy in Detection of Vocal Fold Scarring
- Stroboscopy is necessary to assess vocal fold vibratory
pattern (mucosal wave) during voice production. Abnormality in vocal
fold vibratory pattern is a key indication that vocal fold scar is most
likely present.
- Without stroboscopy, the diagnosis of vocal fold scarring can easily be missed.
Microlaryngoscopy Is a Powerful Diagnostic Adjunct
Microlaryngoscopy is another important diagnostic step that is sometimes required to
fully assess the nature of the vocal fold scar – especially when other
conditions such as vocal fold lesions make it difficult to assess the
presence and extent of scarring.
- Microlaryngoscopy is performed with the patient under
anesthesia. While the patient is asleep, the laryngologist uses a
microscope to obtain a highly magnified view of the voice box – a
better view than can be achieved by a mirror examination. Additionally,
the surgeon can gently and thoroughly palpate the vocal folds, allowing
an assessment of the size, nature, and location of the vocal fold scar.
- Microlaryngoscopy is also indicated when:
- Voice disorders cannot be completely explained by office examination techniques
- Patient cannot tolerate in-office examination techniques due to a strong gag reflex
Key Information
Patient Informed Consent: Anesthesia Risk Versus Diagnostic/Treatment Gains
Microlaryngoscopy
is performed routinely and without incident, however anesthesia is not
without risk. Microlaryngoscopy should therefore be performed only when
indicated, and patients should be informed regarding potential risks.
Vocal Fold Scar Can Cause Inadequate Closure of Vocal Folds
Often, incomplete vocal fold closure seen on stroboscopy is
attributed to vocal fold muscle weakness (paresis). Poor vocal fold
closure most likely indicates either vocal fold paresis or vocal fold
scarring. (For more information, see Vocal Fold Paresis/Paralysis.)
 Red Flag
Without a very careful assessment of the full
range of motion, speed of motion and motion activity of the vocal folds
during a variety of voice and non-voice tasks, an erroneous diagnosis
of vocal fold paresis can be given to individuals who actually have
vocal fold scarring (and vice versa).
Vocal Fold Scarring Often Occurs With Other Lesions
During the evaluation of vocal fold scarring, investigation of other
possible associated lesions, such as vocal fold nodules, polyps, or
cysts, is also necessary. (For more information, see Vocal Fold Lesions.)
- Vocal fold lesions must be investigated by both laryngoscopy and stroboscopy. (For more information, see Laryngoscopy/Stroboscopy.)
- Determining
whether vocal fold lesions accompany vocal fold scarring is important
since the treatment plan is different if is a combined problem exists.
- Vocal
fold lesions may mask vocal fold scarring. Sometimes, because of the
presence of large lesions of the vocal folds, scar tissue cannot be
fully assessed or appreciated on stroboscopy and is not observed until
microlaryngoscopy is performed under general anesthesia.
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Key Glossary Terms
