|Year : 2015 | Volume
| Issue : 2 | Page : 119-122
Minimally invasive video-assisted thyroidectomy: Ascending the learning curve
Michela Giulii Capponi1, Carlo Bellotti2, Marco Lotti1, Luca Ansaloni1
1 General Surgery 1 Unit, Emergency Department, Papa Giovanni XXIII Hospital, Bergamo, Italy
2 Thyroid and Parathyroid Surgery Unit, Surgeal Department, Sant' Andrea Hospital, La Sapienza University, Rome, Italy
|Date of Submission||11-Aug-2013|
|Date of Acceptance||29-Oct-2013|
|Date of Web Publication||24-Mar-2015|
Michela Giulii Capponi
Papa Giovanni XXIII Hospital, Piazza OMS 1, Bergamo 24127
Source of Support: None, Conflict of Interest: None
Background: Minimally invasive video-assisted thyroidectomy (MIVAT) is a technically demanding procedure and requires a surgical team skilled in both endocrine and endoscopic surgery. The aim of this report is to point out some aspects of the learning curve of the video-assisted thyroid surgery, through the analysis of our preliminary series of procedures. Patients and Methods: Over a period of 8 months, we selected 36 patients for minimally invasive video-assisted surgery of the thyroid. The patients were considered eligible if they presented with a nodule not exceeding 35 mm and total thyroid volume <20 ml; presence of biochemical and ultrasound signs of thyroiditis and pre-operative diagnosis of cancer were exclusion criteria. We analysed surgical results, conversion rate, operating time, post-operative complications, hospital stay and cosmetic outcomes of the series. Results: We performed 36 total thyroidectomy and in one case we performed a consensual parathyroidectomy. The procedure was successfully carried out in 33 out of 36 cases (conversion rate 8.3%). The mean operating time was 109 min (range: 80-241 min) and reached a plateau after 29 MIVAT. Post-operative complications included three transient recurrent nerve palsies and two transient hypocalcemias; no definitive hypoparathyroidism was registered. The cosmetic result was considered excellent by most patients. Conclusions: Advances in skills and technology allow surgeons to easily reproduce the standard open total thyroidectomy with video-assistance. Although the learning curve represents a time-consuming step, training remains a crucial point in gaining a reasonable confidence with video-assisted surgical technique.
Keywords: Minimally invasive video-assisted thyroidectomy, minimally invasive thyroidectomy, thyroid surgery
|How to cite this article:|
Capponi MG, Bellotti C, Lotti M, Ansaloni L. Minimally invasive video-assisted thyroidectomy: Ascending the learning curve. J Min Access Surg 2015;11:119-22
| ¤ Introduction|| |
Conventional thyroid surgery has gained such a high standard in terms of mortality and morbidity to let the attention focus on additional outcomes of cosmetics and functionality, thanks to minimally invasive approach.
The first reported case of minimally invasive thyroid surgery was published in 1997;  Since then the procedure has been widely accepted as several studies demonstrated its advantages: Shorter hospital stay, reduced post-operative pain and improved cosmetic results. Minimally invasive video-assisted thyroidectomy (MIVAT) is a specialised procedure. It requires a well-experienced surgeon and suitable surgical skills, which evolve from appropriate training.
We reviewed the data of the beginning of our experience with minimally invasive thyroid surgery and selected our first series of 36 video-assisted procedures (surgical results, conversion rate, operating time, post-operative complications, hospital stay and cosmetic outcomes) to analyse some aspects of the learning curve we dealt with when we introduced this technique in our practice.
| ¤ Patients and methods|| |
Over a period of 8 months, among the patients who referred to our tertiary university hospital, we selected 36 patients for minimally invasive video-assisted thyroid surgery: 29 females (85.5%) and seven males (14.5%) with a mean age of 50.4 years (range: 28-72 years). We used the following inclusion criteria: 
- Age ≥18 years old;
- Total thyroid volume <20 ml ultrasonographically determined;
- Absence of biochemical and ultrasound findings of thyroiditis.
Patients were excluded if they had:
- Enlarged lymph nodes in the neck;
- Previous neck surgery or irradiation;
- Pre-operative diagnosis of thyroid cancer.
Patients underwent pre-operative fine-needle aspiration (FNA) cytology routinely and admission diagnoses were: suspicious follicular lesion in 18 cases (50%); benign multinodular goitre in nine cases (25%); toxic multinodular goitre in eight cases (22.2%); Hürthle cell neoplasm in one case (2.8%).
All patients underwent pre-operative direct laryngoscopy to assess vocal cord motility and signed an informed consent, which included the permission of collecting video and photo data.
All operations were attempted by the same experienced surgeon. The technique used is the one originally described by Miccoli et al.  The procedures were carried out through a 2 cm central incision above the sternal notch under endoscopic vision, using a 30° endoscope 5 mm in diameter and were totally gasless. Small conventional forceps and instrumentation derived from ear-nose-throat and spinal surgery (forceps, scissors, spatulas, spatula-shaped aspirator) for dissection were used for the first five procedures, then a dedicated set for the following ones. No drains were left inside. Conversion to open surgery was defined as the need to perform a longer incision. All operation videos were saved and analysed after the surgery.
Patients were asked to evaluate the cosmetic result of the video-assisted procedure 45-60 days after the operation, by means of a four grade scale of satisfaction: not sufficient, sufficient, good, excellent. 
| ¤ Results|| |
A total of 36 total thyroidectomy was performed. In one case, a parathyroidectomy for consensual adenoma (15 mm in largest diameter) was added. The procedure was successfully carried out in 33/36 cases (conversion rate 8.3%). Conversion was required in three patients: in two cases, the identification of the recurrent laryngeal nerve (RLN) was uncertain and in one patient bleeding from the upper pedicle forced to extend the skin incision.
The mean operating time was 109 min (range: 80-241 min) and reached a plateau after 29 MIVAT [Table 1]. Final histology showed benign goitre in 13 cases (36.1%), follicular adenoma in 10 cases (27.8%), toxic multinodular goitre in eight cases (22.2%) and Hürthle cell adenoma in one case (2.8%), low risk T1 papillary carcinoma in four cases (11.1%). Post-operative complications included: three transient RLN palsies (registered among the first five video-assisted procedures performed) and two transient hypocalcaemias; no definitive hypoparathyroidism was registered. There was no post-operative haematoma or seroma. Post-operative pain was slight. No patients required post-operative administration of further analgesics. The hospital stay was 2 days for all patients. Post-operative calcium supplementation therapy was not needed in any patient except 2, who were administered with 1000 mg calcium the following 10 days after surgery. The cosmetic result 45-60 days after operation was considered excellent by most patients (34/36, 94.5%), good by 2 ones (5.5%) [Figure 1]. Transient hoarseness completely recovered in all patients within 6 months after surgery, as confirmed by laryngoscopy.
|Figure 1: Minimally invasive video-assisted thyroidectomy cosmetic result|
45 days after surgery
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|Table 1: Minimally invasive video-assisted thyroidectomy: Operative time distribution during the learning curve|
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| ¤ Discussion|| |
For a minimally invasive procedure to gain universal acceptance the intrinsic goal of the treatment should not be compromised in the pursuit of less-invasive surgery. Mortality and morbidity rates should be at least comparable with those of conventional surgery and the minimally invasive procedure should take additional benefits to patients, such as reduced post-operative pain, shorter hospital stay and better cosmetic results. Finally, the technique should be reproducible. 
The training is a crucial step while gaining any video-assisted surgical technique and it should be defined in detail to exploit it completely.
However, the learning curve is more than a shortening of the operative time: Skillfulness, proficiency and stability of operation should be achieved. 
We introduced MIVAT in our practice in 2005, after attending about 20 hours of instructional courses on porcine models. Furthermore, we decided that the surgical team should have been always the same, to get on well together rapidly, which is the first recommendation to surgeons who start a new procedure.
Second, patients should be strictly selected, on the basis of the actual confidence of the surgeon with the technique at the time of the diagnosis. At the beginning of our experience we used stricter eligible criteria than the ones we adopt at present. FNA diagnosis of low risk papillary carcinoma at admission was an exclusion criteria because we were in the learning curve period and also because cancer represented a controversial indication for MIVAT at that time, even if oncologically possible as demonstrated by Miccoli et al. , Indeed the oncologic outcomes of the four patients incidentally detected with low risk T1 papillary carcinoma were satisfactory in spite of the learning curve.
We advise not to perform MIVAT in cases in which selection criteria are not respected: such attempt to speed the course of the training period does not bring any real advantage and results in a higher conversion rate.
Although MIVAT remains a surgical option for a low number of patients, about 10% of all patients,  the learning curve demonstrates a sharp increase in selection criteria with growing experience: indications for MIVAT can evolve, allowing the use of MIVAT for larger volume goitres (30 ml) and for low-grade thyroid carcinomas. 
Moreover, we believe that the use of dedicated instrumentation is essential as it is extraordinary useful to create a comfortable working space and maintain bloodless the operating field.  In our first cases, we used small conventional forceps and instrumentation derived from ear-nose-throat and spinal surgery for dissection. We noticed a rapid ascent in the learning curve in terms of feasibility and operating time from the sixth procedure, when we adopted the more comfortable dedicated instrumentation.
The performance of safe and effective video-assisted thyroid surgery requires in-depth knowledge of biology and pathology of thyroid diseases and maximum ability: achieving low morbidity rates demands meticulous attention to operative technique and anatomic details. Particularly, it must be emphasized that video-assisted thyroid surgery requires fine technique to prevent injuries to the RLN and parathyroid glands.
Acceptable rates of permanent RLN injury should be 1% or less and permanent hypoparathyroidism 2% or less.  During our preliminary experience, we registered 3 temporary palsies of the RLN (8.3%), a too high rate of injury if compared with the established results of conventional thyroidectomy. Through a careful analysis of the operative videos we noticed that it was probably due to excessive traction over the thyroid lobe, which resulted in stretching of the recurrent nerve.  After first five procedures we rigorously avoided every potential traumatic manoeuvre and no more damage occurred.
On the contrary, in our hand, transient symptomatic hypocalcaemia was slightly more frequent with the standard procedure than with MIVAT, thus confirming the encouraging results already reported. 
MIVAT is a technique with early outcomes that are at least comparable to those of conventional TT, with some endpoints appearing superior. With the help of the optical magnification, the superior laryngeal nerve can be easily identified and respected with enhanced results in swallowing and voice.
The technique offers the advantage of a lower post-operative pain and a better cosmetic result. In our series, no additional analgesics were required during the post-operative course as MIVAT does not need to place patient's head in hyper-extended position. Furthermore, patients did not registered paraesthesia or constant discomfort and sensation of foreign body in relation to long scars and excessive subcutaneous and subplatysmal dissection. Shorter skin incisions and the absence of musculo-cutaneous flap have contributed to obtain the satisfactory cosmetic results patients declared at follow-up.
A great concern arises about operative time and consequently costs of minimally invasive thyroid surgery. In our experience, the operation time gradually decreased and remained steady after 29 case, in accordance with previously estimated learning curves of 20-30 cases: , We decided to add the analysis of further following seven procedures of our series (which is about 20% extra) to state the achievement of stable results. Certainly MIVAT seems to be easier and faster to learn than other endoscopic procedures  and its safety rate suggests the procedure to be performed in out-patients settings, , thus reducing hospital costs.
In conclusion, MIVAT is a very specialised approach, requires knowledge of specific handling techniques and a relatively low number of cases to be qualified to perform the procedure. 
Its results appear to be comparable with those of the traditional surgical technique or even superior in terms of pain and cosmetic results when used in properly selected patients.
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