Discussion
CRS may cause abnormal nasality and adverse effects on quality of
life.14 However, only a few studies have investigated
nasality changes in CRS patients. Hong et al. demonstrated that the
nasalance of patients with bilateral nasal polyposis was significantly
lower than that of healthy controls before operation and increased to
the level of the healthy controls 3 weeks after FESS.7Two studies had investigated the impact of FESS on nasalance change in
patients with high disease burden CRS with nasal polyps, and found that
the nasalance returned to nearly preoperative level 3 to 6 months
following FESS.11,15 To the best of our knowledge,
this is the first study to discuss nasality in patients with unilateral
CRS. These patients had only one side nasal airway involvement and had
relatively less disease burden with favorable surgical
outcomes.16 In the subjective evaluation, we found
that 33.3% of unilateral CRS patients had abnormal nasality by
self-scoring VAS and that 47.6% had noticeable abnormal nasality as
evaluated by their partners. In addition, a negative correlation was
found between the Lund-Mackay score and nasalance in patients with
unilateral CRS.
Hyponasality is present in patients with sinonasal disease with
obstruction of nasal airways.7 Sinonasal surgery
alters the structure and patency of the nasal cavity, and the acoustic
characteristics of the vocal tract change with it. Behrman et al.
reported that decreased nasal mucosal surface area and widened nasal
passages after sinonasal surgery will result in a decrease in acoustic
damping and an increase in acoustic coupling with the paranasal sinuses.
Therefore, sinonasal surgery may result in increased
nasalance.17 Renata Soneghet et al. reported that the
mean nasalance values of [i] increased significantly from 27.2%
preoperatively to 39.8% 1 month after FESS.1 Kim et
al. reported an initial increase in nasalance following FESS which
eventually returned to near pre-operative values 6 months
later.18 However, a trend toward increase of nasalance
in [a], [i], [u] was still found after surgery, although the
increase did not reach clinical significance (all P-valuesbetween 0.05 and 0.1). Otherwise, the postoperative sinonasal condition
was not mentioned, and recurrent nasal polyps or edematous mucosa may
also cause a decrease in nasalance postoperatively.
In our study, all patients underwent endoscopy, and the sinonasal
mucosal status was nearly normal postoperatively. We found a significant
increase in nasalance 1 year after FESS, particularly in patients who
received wide opening FESS. The nasalance of [i], [m], and
[MiMi] were significantly increased. The Lund-Mackay CT score was
negatively correlated with preoperative nasalance ([i] and [m])
and positively correlated with postoperative nasalance change ([i]
and [m]) with clinical significance. A higher nasalance change in
patients who underwent wide opening FESS may be due to a relatively
lower nasalance level preoperatively and a wider open sinonasal cavity
postoperatively. The significantly increased nasalance following FESS
was accompanied by a significant improvement in the subjective nasality
assessments (in both patient-reported VAS scores and questionnaires
reported by patients’ partners). These results imply that an increase in
nasalance corresponded to a nasalance return to a relative normal value.
The nasalance did not correlate with the subjective VAS of abnormal
nasality, but a significant negative correlation was found between
preoperative nasalance ([a], [i], [u]) and the severity of
nasal obstruction. A previous study revealed a correlation between the
increase in the volume of the nasal cavity and the increase in the
nasalance score in patients who underwent FESS due to
CRS.9,19 These results imply that the patency of the
nasal airway has a significant impact on nasalance change. The healing
and regeneration of the sinonasal mucosa happens usually within 6
months, and mucosal vibration may normalize
subsequently.20 Platt et al. found that the bony
structure continued to change in average 14.3 months after wide opening
ethmoidectomy.21 This alteration in the bony framework
of the paranasal sinuses after operation may be another reason for the
nasalance change after operation. In our study, a more significant
change in nasalance was found in patients who underwent wide opening
surgeries.
There are still some limitations in this study, and the first is the
limited sample size included in research. Some patients can’t complete
the entire post-op follow up and they were excluded from the study.
Another limitation of this study is the lack of normal controls for
comparison. However, the nasalance value is variable between individuals
and may be influenced by age, race, sex, geographic regions, and
habitual language.4,22,23 Therefore, a large sample
size is needed to establish normative values. In our study, we compared
pre- and post-operative nasalance to eliminate the possible bias of
individual differences. Furthermore, our post-operative nasalance was
close to the value of Mandarin speakers reported in the normal
papulation.22