The incidence of thyroid diseases is variable among the general population.
There are two major categories, either benign or malignant thyroid
diseases. Multinodular goiter (MNG) is the most frequent endocrine
disorder that requires surgical intervention. There are many surgical
techniques available for MNG, such as subtotal thyroidectomy (ST),
near-total thyroidectomy (NTT), hemithyroidectomy plus subtotal resection (Dunhill
procedure), and total thyroidectomy (TT) [1].
For more than a
century, ST has been frequently performed with the expectation of taking care
of nearly all compressive symptoms and cosmetic concerns associated with
an MNG with no postoperative hypothyroidism and major morbidity [1].
Total thyroidectomy is a surgical procedure for the treatment of various
thyroid diseases with the removal of all thyroid gland tissue. However,
the use of total thyroidectomy procedure is deemed not safe for thyroid
[2].
ST has many
limitations. Recurrence of MNG was reported in 50% of cases on long term follow
up. The function status of the remnant thyroid tissue is
still unpredictable. In addition, a significant percentage of cases
with postoperative hypothyroidism requires replacement therapy. In some
cases, injury of RLN was reported following ST [3].
Recently, TT has
replaced ST as an optimal surgical technique for MNG in the clinical field of
the majority of endocrine surgeons, and with good results and justification. TT
for MNG had many advantages of removal of all tissue with subsequent no
risk of recurrence. Also, it can resolve all the compressive symptoms of MNG.
Lastly, it eliminates any possibility of incidental thyroid cancer (ITC)
[4].
This study aimed
to assess the incidence of complications with total (TT) and subtotal
thyroidectomy (STT) among patients with benign goiter disease
and incidental malignancy in MNG.
Patients and methods
This prospective
study was conducted in the period between November 2016 and December 2019. The
study followed the Code of Good Practice and the guidelines of the
Declaration of Helsinki, seventh revision, 2013. It was approved by the Medical
Ethics Committee of the Faculty of Medicine at Assiut University. Written
informed consent was obtained from all participants.
Patients
All patients with
benign thyroid enlargement, either diffuse or nodular, and candidate for
surgical treatment, were enrolled in the study. Any patient with malignant,
recurrent, or unilateral multinodular goiter was excluded from the study.
Sixty patients with benign goiter disease were enrolled in the study.
Those patients were divided into two equal groups based on the type of
operation, either total (TT Group, n=30)
or subtotal thyroidectomy (ST Group, n=30).
Preoperative assessment
All enrolled
patients were subjected to detailed history taking and thorough physical
evaluation. The baseline level of thyroid-stimulating hormone,
T3, T4, and serum calcium, was recorded. For medicolegal purposes, vocal
cord examination with a laryngoscope was done. Thyroid evaluation with
ultrasound was done with fine-needle aspiration cytology in
the suspicious patient. In the case of huge goiter, plain X-ray was
performed, and computed tomography was required in cases with retro-sternal
goiter. The preoperative cardiopulmonary assessment was done for all
patients.
Operative techniques
Total
extracapsular thyroidectomy
The surgical
technique for each operation was the same. After making an incision in the
lower anterior neck and dissecting the subhyoid muscles
(without cutting them), the thyroid gland was exposed, and the
thyroid capsule was dissected, and the lobe was delivered to the wound
after the middle thyroid vein was ligated. In order to preserve the
external laryngeal nerve, the superior thyroid vessels were dissected, ligated,
and divided in all patients, as close as possible to the thyroid gland.
The recurrent laryngeal nerves have been systematically searched,
attempts have been made to identify and preserve the parathyroid glands on
each side of the thyroid gland with identification of inferior thyroid
artery at both sides with dissection and preservation of its branches
to parathyroid glands.
Bilateral subtotal
thyroidectomy
The identification
of inferior thyroid artery branches to the thyroid gland was made with its
ligation near the capsule. The main trunk of that artery was preserved. A
small slice only of posteromedial gland tissue on each side was preserved
with suturing its capsule to the pretracheal fascia to confirm homeostasis.
Statistical analysis
Data were analyzed
using the statistical package for the social sciences, version 20 (SPSS Inc.,
Chicago, IL, USA). Continuous data expressed as mean ± SD
and compared with the Student t-test, while nominal data expressed as
frequency (percentage) and compared with Chi2 test
or Fisher's exact test. The level of confidence was kept at 95%, and hence, the
p-value was significant if
<0.05.
Results
The majority (80%
of TT group and 90% of ST group) were females. The two groups had insignificant
differences regarding age and sex (P>0.05).
Baseline thyroid function and ultrasound findings
among enrolled patients (tabl. 1)
Only one patient
of the TT group and five (16.7%) of the ST group had a toxic pattern of thyroid
function while all other patients had a euthyroid pattern. Based on ultrasound
findings, the majority of patients (96.7% of TT and 83.3% of ST groups)
had a bilateral multinodular goiter. Diffuse gland enlargement was found
in one patient of the TT group and 4 (13.3%) of the ST group. A dominant
thyroid nodule was observed in only one patient of th e ST group.
Both groups had insignificant differences regarding baseline thyroid
function and ultrasound findings.
Clinical diagnosis of the enrolled patients (tabl. 1)
Simple nodular
goiter was the diagnosis of 19 patients (63.3%) of the TT group and 10 (33.3%)
of the ST group. Only one patient of the TT group had a primary toxic
goiter. In the ST group, primary toxic goiter, secondary toxic goiter,
simple nodular goiter, and dominant toxic nodule were found in 4 (13.3%), 10
(33.3%), 15 (50%), and 1 (3.3%) of the patients, respectively.
Table 1. Baseline data of patients in
studied groups
Note. Data expressed as frequency (percentage), mean (SD);
p-value was significant if <0.05; * - p-value
cannot be calculated due to the small number of cases in subgroups
Postoperative complications in both groups (tabl. 2)
Only one patient
of TT group and two patients of ST group developed wound infection. Transient
and permanent RLN injury occurred in one patient of the TT group
compared to none of the ST group. Also, hypoparathyroidism was found in two
patients (6.7%) of the TT group and none of the ST group. One
patient in each group developed postoperative bleeding. There was no
significant difference between both groups as regards the development of
postoperative complications.
Table 2. Postoperative complications
in both groups
Data expressed as
frequency (percentage). p-value was
significant if <0.05.
Postoperative histopathological diagnosis
4 (13.3%) patients
in the TT group had malignant features on the histopathological examination
compared to 6 (20%) patients in the ST group (p=0.488). Patients in the ST group with incidental
malignancy on pathological evaluation required
re-operation (completion thyroidectomy).
Discussion
Total
thyroidectomy (TT) and subtotal thyroidectomy (ST) are the most common surgical
procedures used for benign thyroid disorders. The choice of such a
procedure aims to eradicate the disease and minimize postoperative
complications [5]. Subtotal thyroidectomy was preferred because of the low
incidence of postoperative complications but had the disadvantage of a
high recurrence rate [6]. Recently, there were many studies suggested that
TT has an incidence of complications similar to ST [7]. Currently, no consensus
about the safety and effectiveness of TT compared to ST or Dunhill
operation has been reported [8]. However, the risks of TT do not
overweight the cumulative operative risks for recurrent goiter after ST or
near-total thyroidectomy. This evidence is in favor of TT for the
treatment of benign MNG [9].
Pappalardo et al.
reported a recurrence rate of 14.5% in patients who received medical treatment
after subtotal thyroidectomy and 43% in patients who did not [10]. The
recurrence rate after ST reported in the two most cited meta-analysis
ranged from 0 to 50% [11-13]. Other studies revealed that the
mean recurrence rate in ST was 10.0%, and TT was significantly better than
ST in terms of frequency of recurrence [9, 14]. Only one Longitudinal study
reported that the recurrence rate was (0.3%) after TT. So, the authors of
both meta-analyses stated that TT is the best surgical option for benign
multinodular goiter [11]. Another study showed that the recurrence
rate tended to increase with time of follow up. It was 8.2% at five
years and doubled (15.5%) at ten years [9].
Re-operation for
thyroid disease recurrence has been associated with a high complication rate
as the fibrous tissue disturbs normal anatomical architecture. There was a
10-fold increase in RLN and parathyroid gland injuries [15]. There was also
an increase in wound infection and bleeding rates [16].
Another limitation
of subtotal thyroidectomy is the malignant potential of thyroid nodules. The
occult cancer rate varies between 7-10% [17]. Castro et al. reported
that 5% of thyroid nodules have malignant characteristics [18]. The most
common reason for re-operation (completion thyroidectomy) for benign MNG
is an incidental finding of occult malignancy in histopathological
examination. Re-operation carries a higher risk of RLN and parathyroid
injuries [19]. One of the advantages of TT is avoiding completion
thyroidectomy for occult cancer and its related risks [8]. Incidental thyroid
cancers have been detected in 3-16.6% of apparently benign goiters after
TT or BST in various studies [12, 20]. A meta-analysis done by Li
showed that the incidence of thyroid cancer was comparable between TT
and ST [21]. This is consistent with our study; the incidence of occult
malignancy in the histopathological specimens was 16.7% (10% after ST
vs 6.7% after TT). All patients in the ST group with occult malignancy
required completion thyroidectomy.
The most common
complications following thyroidectomy are RLN injury, parathyroid gland injury,
and bleeding. Some studies reported a higher incidence of complications after
TT [22]; others reported lower risk [23, 24]. However, some other studies
reported no significant difference in complications between TT and ST [5, 17].
The incidence of
temporary RLN injury is (5-11%) while permanent injury (1-3.5%) [22]. Based on
the analyses of Barczynski and Thomusch, the incidence of permanent
RLN injury was 0.8% after ST, 1.4% after Dunhill operation, and 2.3% after
TT [9, 25]. 2 recent meta-analyses revealed that TT is more effective
in preventing goiter recurrence than other limited resection while has
identical morbidity as regards the potential risk of RLN injury [11, 12].
Another study
showed the rate of transient and permanent RLN palsy (1.7-0%, respectively)
after both TT and ST [26]. Ozbas et al. revealed that tran-sient/permanent
RLN injury (1.9-0%, respectively) after TT, which even less than that for
the ST group (4-1%) [7]. Ciftci reported no significant difference in
the incidence of transient/permanent RLN palsy between TT and ST groups.
The risk of RLN injury depends on the extent of thyroid resection (TT vs
ST), underlying thyroid pathology, and volume of surgeon experience
[5]. In the current study, there was only one patient with transient RLN
injury and another one with permanent injury after TT compared to
none after ST. In agreement with previous studies, there was no
significant difference between both groups in incidence of RLN injury
(p=1.000).
The incidence of
temporary hypoparathyroidism is (20-30%) while permanent in (1-4%) [22].
Permanent hypocalcemia results from unintentional removal of parathyroid glands
or disruption of the blood supply of parathyroid glands. A large multicenter
study included 5195 patients who underwent thyroid resection in 45 hospitals
presented significantly higher rates of RLN palsy and hypoparathyroidism following
TT than those after ST [22]. Tezelman reported an incidence of transient/persistent
hypocalcemia of 8.4-0.8% after TT and 1.4-0.4% after ST [20]. Another
study reported an incidence of transient/persistent hypocalcemia of 15.1-0.4%
after TT and of 17.5-0% after ST. There was no significant difference
between both groups in the incidence of transient and permanent hypocalcemia
[5]. This was consistent with our study, which revealed no significant
difference between both groups (p=0.492)
regarding developing hypoparathyroidism.
According to the literature,
the frequency of postoperative hemorrhage and wound infection ranges between 0
and 2% [20]. In the study by Ozba, the hemorrhage rate was 0.4% after TT
and 0% after ST, and the wound site infection rate was 0% after TT and 0.6% after BST
[7]. In the current study, there was no significant difference between TT and
ST group as regards the incidence of hemorrhage and wound infection (p=1.000). In agreement with our study,
Ciftci et al. also reported the same result in both groups [5].
According to our
study, there was no significant difference between 2 groups as regard age, sex,
thyroid function, ultrasound findings, and clinical diagnosis. Analysis of the
data from all operations performed by one of three highly experienced
surgeons demonstrated a low complication rate following total thyroidectomy,
more or less identical to those following subtotal procedures [9]. Also, Padur
et al. revealed that TT as safe and effective as ST for most of the
thyroid diseases [27].
Based on the above
evidence, we would conclude from our study that total thyroidectomy is a safe
and effective procedure for benign thyroid diseases as subtotal
thyroidectomy. Furthermore, ST is associated with a high recurrence rate
and leaving behind foci of occult malignancy, which required completion
thyroidectomy with its related risks. So, we consider that TT has a
significant advantage over ST, especially in the hands of expert surgeons.
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