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Mammana et al. Mini-invasive Surg 2020;4:37 I http://dx.doi.org/10.20517/2574-1225.2020.24 Page 5 of 7

Table 1. Main published series of robotic thymectomy for myasthenia gravis
Ref. Year No. Approach Complete remission rate (%) Morbidity (%) Mortality (%)
Freeman et al. [20] 2011 75 Left 28 6.7 0
Ismail et al. [19] 2013 273 Left 57 1.6 0
Marulli et al. [21] 2013 100 Left 28.5 6.0 0
Keijzers et al. [22] 2015 125 Right 28.2 7.2 0
Kumar et al. [23] 2017 71 Left 38 7.0 0

Right-sided approach
The mediastinal pleura is incised just anterior and medial to the right phrenic nerve, starting from the
cardiophrenic angle and progressing upwards, and all anterior mediastinal tissue is separated from the
nerve and the superior vena cava. The retrosternal parietal pleura is then opened medial and parallel to
the right internal mammary vessels, and mediastinal tissue is dissected off the sternum anteriorly and the
pericardium posteriorly, until the left brachiocephalic vein is identified. The thymic veins are identified,
clipped, and dissected. The superior horns are then identified and divided from the thyroid gland. The
left pleura is then opened and after the left phrenic nerve is identified, the dissection of the thymus is
completed and the specimen is extracted as described above.

OUTCOMES OF ROBOTIC THYMECTOMY
The safety profile of RATS thymectomy seems excellent, with a morbidity rate ranging between 1.6% to 7.2%
and no perioperative mortality in any of the studies [Table 1]. The most commonly reported complications
include myasthenic crisis, bleeding and chylothorax [19-23] . In terms of postoperative results (blood loss,
morbidity rate and length of hospital stay), several single-center case series have demonstrated better
outcomes with RATS than with open thymectomy [24-26] . A multicenter study from the French database
EPITHOR confirmed that patients undergoing thymectomy with minimally invasive procedures (mostly
RATS) had fewer postoperative complications and a shorter hospital stay compared to patients operated
[27]
on by sternotomy . However, because of important disparities in baseline patients’ characteristics, no
[27]
firm conclusions about the superiority of one technique over the other could be drawn . Finally, a recent
systematic review compared postoperative outcomes after thymectomy by RATS or VATS, and found no
[28]
significant difference in terms of morbidity, conversion to open and length of hospital stay .

As far as neurological outcomes are concerned, in general, non-surgical factors that are believed to decrease
the effectiveness of thymectomy in palliating symptoms of MG are the presence of thymoma (as compared
[29]
with thymic hyperplasia), duration of symptoms longer than 1 year, and older age . The completeness
of removal of all thymic foci, on the other hand, is the single most important surgery-dependent variable
that influences postoperative neurological outcomes [10,11] . Unfortunately, because of differences in surgical
approaches and operative techniques, it is not always easy to determine the extent of removal of thymic
tissue from retrospective studies. In an attempt to overcome this issue, the following definitions have
been proposed: basic thymectomy includes the removal of the thymic gland without any surrounding fat;
extended thymectomy includes removal of the thymus with surrounding fatty tissue of the neck and the
mediastinum ; finally, the maximally extended thymectomy procedure, proposed by Jaretski, consists
[30]
in removal of the thymus with all mediastinal fat, from the level of the upper poles of the thyroid gland
[10]
to the diaphragm, with opening of both pleural cavities . Clearly, the maximally extended procedure
is recommended to achieve the highest remission rates. Zielinski and colleagues, in fact, have compared
neurological outcomes of patients who underwent thymectomy according to 3 different techniques,
demonstrating better complete remission rates in the group of patients treated by the most radical operative
technique .
[31]
Following robotic thymectomy, all authors report satisfying complete remission rates, with values ranging
from 28% to 57% [19-23] . These results are in line with complete remission rates achieved by transsternal