DISCUSSION
Facial nerve preservation is the most important problem in parotidectomy
with benign tumors. However, quality of life after parotidectomy should
not also be ignored. FS and facial aesthetic have the potential to
profoundly impact quality of life after parotidectomy. So, the purpose
of this study was to evaluate the complication, including FS, and
aesthetic effects of insertion of ADM after parotidectomy with the
method of propensity score matched analysis.
One of the mechanisms of FS is caused by an aberrant regeneration
between the postganglionic parasympathetic nerve fibers that innervate
secretion of the parotid glands and the sympathetic nerve fibers that
control the subcutaneous sweat glands and vessels after parotidectomy.
(21) The reported that the overall incidence of FS following
parotidectomy has been great difference. Most previous reported the
subjective incidences of FS are between 10% and 40%, and the objective
incidences are up to 90%.(22) One reason for this difference may lose
to estimate the no clinic symptoms of gustatory sweating and and
gustatory flushing. The other reason may the differences research
methods. A reported that the incidence of FS in a prospective group was
higher than in a retrospective one. The differences may be clarify that
the prospective group was more aware of the possible incidence of FS and
symptoms of FS may disappear with time in the retrospective group.
A variety of treatment have been reported over time with advantages and
disadvantages. Botulinum toxin type A has become the first-line therapy.
However, the durations effect may short from 12.1 months to 17.3 months.
(23) Scholars have also reported that building a barrier in the surgical
site after parotidectomy can help to prevent FS, including the
sternocleidomastoid muscle flap, the temporoparietal fascia flap, the
superficial musculoaponeurotic system flap(SMAS), the free or
vascularized dermal fat graft, and ADM.
The SMAS layer is the superficial cervicofacial fascia. The SMAS flap is
placed between the skin and the surgical site of the parotid region. The
SMAS flap can effectively prevent the occurrence of FS following a
parotidectomy in benign tumors. (24) The use of SMAS flap is limited in
the malignant tumors or the obese patients, which is being resection or
sometimes insufficient to cover the surgical site. Another limitation of
the SMAS flap may more injure to the marginal mandibular branch or
cervical branch of the facial nerve.
The free fat graft is also common barrier after parotidectomy. A
reported that ADM and free fat grafts were an equal effective in
preventing FS and other complications, including facial palsy, sialocele
or salivary fistulas, and sensory deficit. (25) Nosan et al. (26) used
free abdominal dermal-fat grafts to preserve the periauricular
depression of 9 patients undergoing parotidectomy, and the results
showed that the aesthetic scores was improving without significant
complications. However, the shortcoming of grafts may be the need of a
second surgical site with potential wound infection. The other
shortcoming is the potentially unpredictable reabsorption rate without
continuous efficiency. Some previous reported reabsorption rates were
high with vary from 20% to 90%. (11)
In recent years, ADM has been used in plastic surgery and parotidectomy.
Hartzell et al. (27) reported ADM have a satisfactory effect and safe
material for breast augmentation. In 2007, Chen et al. (28) reported ADM
provided a satisfactory aesthetic result with a low incidence of FS in
parotid haemangiomas. Govindaraj
et al. (7) reported the use of ADM in the prevention of FS compare with
control group for superficial parotidectomy. 64 patients were randomly
equal assigned to two groups. The results demonstrated
the subjective incidences of FS
were 9.3% in control group and 3.1% in ADM group. The
objective incidence of FS was 40%
in control group and 0% in ADM group. However, the complication rate of
25% in ADM group was higher than 9% in control group. In 2008, Wei et
al(29) reported similar conclusion
in the incidence of FS after superficial and partial superficial
parotidectomy. The subjective and objective incidences of FS were
recorded in 61% and 23% from the control group and 2% and2% from the
ADM group. Furthermore, the complication of sialocele or salivary
fistula in 17% from the control group was higher than that 2% from the
ADM group. Luo et al. (19) reported the subjective incidences of FS in
ADM group was 1 patient (3.4%) lower than that 14 patients (34.1%) in
the control group for total parotidectomy. No cases of complication were
observed in either group.
In our study, the subjective incidences of FS in ADM group were 1
patient (3%) lower than that 9 patients (30%) in the control
group(P =0.015). And the
overall
complication rate of 5(17%) in
ADM group was lower than 13(43%) in control group(P =0.024). The
incidence of FS for both group in our study was resemble to the previous
literature. (7, 19, 28, 29) The results of complication have been
analogue to the conclusion of Wei et al(29), while difference from the
conclusion of Govindaraj et al(7). The reason of difference may partly
because the research methods were difference. Although our study has
used retrospective study as same as the previous literature, we matched
the baseline data according a propensity score matched analysis. We
matched some important data including age, gender, type of tumor, size
of tumor, volume of specimen, type of parotidectomy, hypertension and
diabetes mellitus, which may reduce the bias of data and increase the
persuasiveness of conclusions.
In our study, the complication of facial palsy and sensory deficit were
no statistical significance. The incidence is related to the surgical
technique, tumor size and location, individual feeling etc. The
incidence rate of Sialocele or Salivary 1(3%) in ADM group was lower
than 6(20%) in control group(P =0.108). However, postoperative
drainage and time were significantly decreased or lower in the ADM group
compared with the Control group (Fig. 2A and 2B). In the present study,
Although the incidence rate of Sialocele or Salivary was no statistical
significance, ADM patients experienced a lower rate of postoperative
drainage and time when compared with control group. This difference of
Sialocele or Salivary and postoperative drainage were thought to be
related to the use of the barrier of ADM. Some previous study has shown
similar conclusion. Ye et al. (29) reported one salivary fistula was
noted in the ADM group, while 18 cases developed in the control group
(P = 0.002). We consider that the ADM should completely cover the
exposed parotid and facial nerve surface. ADM graft may replace fascia
to reduce secretion and promptly eliminate the dead space. When the
postoperative drainage is less than 10 ml drainage tube can be removed,
and a proper pressure dressing used for about 3-5 days. So, the ADM
graft may promote the quality of life after parotidectomy.
The aesthetic score after parotidectomy should also be important
considerations. In our study, the subjective aesthetic score for
patients in the ADM group was higher than those in the Control group
(P =0.040). In 2012, a study reported the use of ADM may reduce
postoperative facial contour deformities following total parotidectomy.
(19) Ciuman et al(30) also reported that the extent of parotidectomy was
related to aesthetic score. In 2019, Kim et al. (9) shown insertion of
ADM after parotidectomy, including partial, superficial, and total
parotidectomy, may improve aesthetic score. The results also
demonstrated the aesthetic score was related to gender and
complications. Interestingly, the results showed that women were more
satisfied than men. We consider the subjective aesthetic score may no
difference in both group before the study. Our research results
indicated the factor of subjective aesthetic score are manifold. We
guess the factor is related to the age, gender, incision, size of tumor,
sample volume, complications, individual feelings etc. There are need
further study.
Our study was limited by the small sample, relatively short follow-up
time. The FS and aesthetic score were evaluated by subjective methods
without objectively assess. The reason is the FS and aesthetic score are
higher related to the subjective evaluation than the objective
evaluation. So, even if the starch iodine test is positive, or the
aesthetic score is low, if a patient suffers no symptoms or satisfied
then no intervention is required.
In conclusion, the present clinical study suggests that ADM graft are
effective in preventing FS and improving aesthetic score after
parotidectomy. More RCTs are needed to confirm
this conclusion and prove the influencing factors of aesthetic score.