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of the mucosal wave, whereas digital kymography can be used
to provide a complete three-dimensional profile of vocal fold
vibration dynamics.23,24 Although these new techniques are
superior to stroboscopy, there are some limitations to their
use. High-speed imaging systems are still too expensive to be
widely used in clinical practice, gathering larger data sets is
problematic because of that fact, and there are no general ac-
cepted clinical protocols in laryngology for these techniques.25
After performing the multivariate regression analysis, some
factors, such as the type of cordectomy and the existence of
a nonvibrating segment, were set apart from others and were
proven to significantly correlate with various levels of dysplasia
(P < 0.05). However, after logistic regression of all chosen fac-
tors (ie, cordectomy type and stroboscopic signs—glottic occlu-
sion, phase symmetry, periodicity, amplitude of vibrations,
mucosal wave, and nonvibrating segment), only the abnormal
amplitude of vocal fold vibrations was observed to occur signif-
icantly more frequently for recurrent disease in the group with
mild dysplasia and in all patients. None of the factors was signif-
icant for disease progression. The presence of some factors
placed the patients at higher risk of recurrence and progression
of the disease. The patient group with mild dysplasia and abnor-
mal vocal fold vibration amplitudes had a 2.93 times greater risk
of recurrence, and the group with nonvibrating segments was at
4.62 times greater risk compared with patients without those
stroboscopic signs. Nonvibrating segment placed those patients
at a 7.17 times greater risk of disease progression than those
patients without nonvibrating segment during stroboscopic
examination. In the group with moderate dysplasia, patients
with insufficient glottic occlusion and abnormal amplitude of
vocal fold vibrations were at a greater risk of recurrence. In
that group, the patients with insufficient glottic occlusion, with
abnormal amplitude of vocal fold vibrations, and the existence
of nonvibrating segment were at a greater risk of disease pro-
gression. In the patient group with severe dysplasia, the greater
risk of recurrence and disease progression aligned with the type
of cordectomy and abnormal amplitude of vocal fold vibrations.
These findings could also be the result of a relatively small
number of patients in the different dysplasia groups, which is
one of the limitations of this study. With a larger number of pa-
tients, some of the stroboscopic signs could be more prominent.
Chang et al 26 conducted a study on a small (18 patients) and
nonhomogenous group of patients with laryngeal dysplasia
and carcinoma to determine whether the clinical features and
clinical appearance of the lesions at presentation correlated
with the outcomes of treatment in terms of cure rate and voice
outcome. They noted that the clinical appearance of the lesion
at presentation, as judged by either still light endoscopy or stro-
boscopy, did not correlate with disease recurrence. The lesion
appearance on still light endoscopy and vibratory characteristics
on stroboscopy also did not correlate with the disease-free inter-
val or voice outcome after endoscopic resection.
Stroboscopy is a subjective method in terms of a stroboscopic
parameter rating system, and the person conducting the proce-
dure should be well trained to reduce variation and bias. Be-
cause of the increasing popularity of stroboscopy equipment
in the general otolaryngology office, it is useful to point out
some limitations of stroboscopy that can benefit less experi-
enced examiner. In this article, we showed that a large and clin-
ically significant number of cases with CIS with absence of
nonvibrating segments can be overlooked when relying solely
on stroboscopy. Caution must be exercised when assessing
stroboscopic findings, particularly during the posttreatment
follow-up period, or if other more sophisticated means of
diagnostics are unavailable.
CONCLUSION
Stroboscopy cannot be used reliably for classifying laryngeal dys-
plasia. Some stroboscopic signs cannot be used as an indication
for performing or not performing laryngomicroscopy with biopsy
in cases of any suspicious vocal fold lesions. In the absence of
more expensive and advanced diagnostic methods, vocal fold dys-
plasia could be precisely classified only by histopathology analy-
sis. The patient age, treatment modality, and stroboscopic signs,
such as abnormal amplitude of vocal fold vibration and the exis-
tence of nonvibrating segment, can be considered as warning fac-
tors for recurrence and disease progression.
REFERENCES
1.
.
2.
3.
4.
.
5.
6.
.
7.
.
8.
9.
10.
11.
.
12.
13.
.
14.
15.
.
Vojko Djukic, et al Stroboscopy in Detection of Laryngeal Dysplasia
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