Complications associated with surgery for RG
The presence of RG is historically known to carry a higher risk of
finding a malignancy and of the development of postoperative
complications (hematoma, transient/permanent hypoparathyroidism, and RLN
dysfunction) compared to cervical goiters81. The most
recent evidence has further confirmed these findings: for example, in a
cohort of 1500 RLNs at risk, substernal extension and a thyroid volume
>100 mL were the only significant factors for postoperative
transient or permanent VC paralysis82. In the IONM
era, a study extracting 42341 operations from the UK Thyroid database
found that RG was an independent factor (OR= 1.36, 95%CI 1.05- 1.77)
that predicted the risk of RN injury, along with revision surgery and
patient age.83 A recent anatomical study has revealed
that iatrogenic lesions of the RNL after RGs’ resections are more
frequent on the right side in comparison to the left one because of the
known anatomical and embryological differences in the development of the
RLN on either side of the neck84.
Regarding postoperative hematoma formation, male sex, the use of
preoperative anticoagulant therapy or postoperative subcutaneous
heparin, and the presence of RG (38 cases) were all significant
predictors in a group of 6900 thyroidectomies85.
Instead, RG was not a significant risk factor in another series of 5900
operations, including a total of 148 RGs (2.5%)86.
Both series, unfortunately, did not provide a definition of RG nor how
the extension was determined. On the contrary, another analysis of the
aforementioned UK registry (n= 53838 entries) revealed in multivariable
analysis that male sex, increasing age, redo surgery, RG (whenever
having an “extension to the thoracic inlet or below”), and total
thyroidectomy were all correlated with an increased risk of reoperation
for bleeding; interestingly, surgeon monthly thyroidectomy rate
correlated with a decreased risk87.
The presence of RG is linked with a major risk of developing clinical
symptoms of hypocalcemia (OR 10.26)88. A recent study
published by Chen et al. provides evidence that there are predictive
factors for this adverse event. This meta-analysis includes 23 studies
and identifies twelve significant risk factors for postoperative
hypocalcemia. In particular, hypoparathyroidism (OR 5.58), total
thyroidectomy (OR 3.59), hypomagnesemia (OR 2.85), and preoperative
vitamin D deficiency (OR 2.32), were those most associated with
hypocalcemia89. In another observational study, RG and
its extension beyond the carina showed a statistically significant
higher risk for transient (less than one year) hypocalcemia (relative
risk = 1.76) after total thyroidectomy90.
Van Slycke and colleagues reported that the higher risk of postoperative
complication is influenced by the surgical approach chosen: out of 95
thyroidectomies performed for RGs, eighty patients (84%) were operated
by cervicotomy and 15 (16%) by cervicosternotomy. The latter group had
a higher risk of temporary recurrent laryngeal nerve palsy (21%)
compared to cervicotomy (4%) and standard thyroidectomy (3%); also,
the risk of temporary hypocalcemia after cervicosternotomy was higher
than with transcervical approaches 62. In addition,
another study highlights how postoperative complications associated with
RG surgical removal are low in the hands of experienced, high-volume
thyroid surgeons, regardless of transcervical or transthoracic
approach91. Instead, the presence of RG was
statistically significant for being an independent predictor of any
complication (OR 2.1), when controlling for age, BMI, gender, and
race91.
Tracheomalacia remains the most dreadful complication in the case of
large RGs, despite its incidence seems to be very
low92. In a series of 40 patients subjected to
thyroidectomy with sternotomy, tracheomalacia was reported in 3 cases,
in absence of any patient- or thyroid-related factor significantly
associated with its development: one patient required tracheal resection
with anastomosis, and two patients required
tracheostomy92. In another paper, 17 cases of
tracheomalacia out of 106 cases were reported, probably caused by
long-standing tracheal compression from RG: this study suggested that
prolonged intubation was sufficient to resolve airways collapse without
tracheal reconstruction in all cases93. Zuo et al.
reported how tracheomalacia could be successfully managed
intraoperatively by suspending the trachea to the overlying skin with
Prolene stitches, despite the fact that they didn’t exhibit either the
exact number of patients affected or the long-term
outcomes94. Despite all the aforementioned
complications, RG was not considered a contraindication for outpatient
surgery: in a recent national survey conducted by the American
Association of Endocrine Surgeons, the diagnosis of RG had no or minimal
effect on same-day discharge95.
The main issue in the analysis of the complications of surgery for RGs
remains the non-standard definitions and characterizations. For
instance, postoperative vocal cord dysfunction may be diagnosed by using
a mirror52, flexible laryngoscopy57,
or a mixture of both82. The timing of what constitutes
a “permanent” hypocalcemia changes (after 657,
versus after 12 months53); the same is true for
hematoma/seroma that should be considered only when needing revision
surgery according to some but not all the authors. To overcome these
limitations, the use of the Clavien-Dindo system may be a solution:
proposed in 1992 and revised in 2004, it appears reliable as a
compelling tool for quality assessment in surgery worldwide. This
classification system was reported as simple, reproducible, logical,
useful, and comprehensive96 and it is beginning to be
implemented also in thyroid surgery97.