**4. Clinical application results of "a layer of TBP"**

A retrospective chart review was authorized and drawn from all 487 patients with PTC who underwent TT with ipsilateral or bilateral CND or plus lateral neck dissection between January 1, 2012 and December 31, 2014 [15]. The study group consisted of 181 patients with using the new surgical concept "a layer of TBP," from January 2014 to December 2014, whereas the control group included 306 sex- and age-matched patients who underwent conventional method from January 2012 to December 2013. There were no significant differences between the groups in tumor size, multifocality, extrathyroidal extension, and number of harvested and metastatic central lymph nodes. The rate of inferior parathyroid gland preservation in situ was significantly improved from 37.9 to 76.3% on the left side (P < 0·001), and from 52.0 to 77.9% on the right side (P < 0.001), in the study group compared with the control group (**Figure 12**). The incidence of transient hypoparathyroidism decreased significantly from 35.0 to 7.2% (P < 0.001). In addition, the excised lymph nodes in the unilateral and bilateral CNDs were compared between the groups. The result showed that significantly more lymph nodes were removed in bilateral CND in the study group than in the control group; however, there was no difference in lymph nodes in unilateral CND between the groups (**Table 1**). Therefore, applying the proposed surgical concept improved the rate of inferior parathyroid gland preservation in situ and decreased the incidence of transient postoperative hypoparathyroidism, along with ensuring the completeness of lymph node

**Variables Control group (n = 306) Study group (n = 181)** *P* No. retrieved lymph nodes 12.74 ± 6.16 (1-30) 13.83 ± 7.07 (3-43) 0.186 No. metastatic lymph nodes 1.94 ± 2.83 (0-14) 1.95 ± 2.75 (0-13) 0.826 No. retrieved lymph nodes in unilateral CND 11.08 ± 5.71 11.33 ± 5.89 0.756 No. metastatic lymph nodes in unilateral CND 1.52 ± 2.20 1.67 ± 2.28 0.393 No. retrieved lymph nodes in bilateral CND 16.04 ± 5.70 18.10 ± 7.00 0.036 No. metastatic lymph nodes in bilateral CND 2.79 ± 3.66 2.41 ± 3.37 0.342

Inferior Parathyroid Gland Preservation In Situ during Central Neck Dissection for Thyroid…

http://dx.doi.org/10.5772/intechopen.78636

27

**2.** Although the success rate of IPTG preservation in situ can be considerably improved using the concept "a layer of TBP" in CND, it is important that the surgeons have the abilities to identify the parathyroid glands and evaluate their blood supply. Some techniques such as no black stain in parathyroid gland by carbon nanoparticles [18] and the intraoperative near-infrared autofluorescence imaging of parathyroid gland [19] are recommended, but we suggest that it is necessary to clinically train the identification of the parathyroid gland

**3.** Parathyroid autotransplantation has been considered a salvage method to avoid permanent hypoparathyroidism. Although the incidence of IPTG preservation in situ was increased greatly after using the concept of "a TBP layer," still about 10% of IPTGs were removed inadvertently or devascularized during thyroid surgery. Therefore, the technique

**4.** The IPTG and its blood supply are frequently involved in the dorsal extrathyroidal invasion of primary tumor or extranodal metastasis of paratracheal lymph nodes; therefore, the preservation of IPTG in situ is unsuitable, and en bloc resection of the thyroid and central neck lymph nodes is recommended. In addition, although the paratracheal area is full of excessive fatty tissue in obese patients, it is also possible to identify and build up "a layer

**5.** Preservation of the IPTG in situ using the approach "a layer of TBP" requires meticulous manipulation during the operation. The requirements for meticulous manipulation include good operation vision, wide operation space, antagonistic traction (the first assistant's), and

of parathyroid autotransplantation should be mastered by thyroid surgeons.

**1.** Some special considerations relative to "a layer of TBP."

**Table 1.** The excised lymph nodes in the unilateral and bilateral central neck dissections.

dissection.

by the naked eyes.

of TBP" by clinical training.

**Figure 12.** The status of inferior parathyroid glands after TT and CND. It was classified into four categories: C1, preserved in situ (vascularized); C2, autotransplanted (devascularized); C3, removed owing to infiltration by the tumor; and C4, not identified. The rate of inferior parathyroid gland preservation in situ was significantly improved on both sides (P < 0.001) in the study group compared with the control group.

Inferior Parathyroid Gland Preservation In Situ during Central Neck Dissection for Thyroid… http://dx.doi.org/10.5772/intechopen.78636 27


**Table 1.** The excised lymph nodes in the unilateral and bilateral central neck dissections.

enters the central neck compartment posterior to the carotid sheath, branches of the ITA need to traverse paratracheal fibrofatty tissue anteriorly to the TBP layer. In general, these branches of the ITA abut against the carotid artery medially and run into the TBP layer; therefore, the TBP layer, carotid artery and ITA branches can easily be retracted laterally, allowing en bloc excision of the paratracheal fibrofatty tissue (**Figure 11A**). The alternative situation is that the ITA branches are not very close to the carotid artery, and the RLN traverses between them (**Figure 11B**). For completeness of dissection and RLN preservation, it is suggested that the paratracheal dissection should be divided into two parts according to the level of the ITA: a dissection cranial to the ITA (between the cricoid cartilage and ITA level) and one caudal to

A retrospective chart review was authorized and drawn from all 487 patients with PTC who underwent TT with ipsilateral or bilateral CND or plus lateral neck dissection between January 1, 2012 and December 31, 2014 [15]. The study group consisted of 181 patients with using the new surgical concept "a layer of TBP," from January 2014 to December 2014, whereas the control group included 306 sex- and age-matched patients who underwent conventional method from January 2012 to December 2013. There were no significant differences between the groups in tumor size, multifocality, extrathyroidal extension, and number of harvested and metastatic central lymph nodes. The rate of inferior parathyroid gland preservation in situ was significantly improved from 37.9 to 76.3% on the left side (P < 0·001), and from 52.0 to 77.9% on the right side (P < 0.001), in the study group compared with the control group (**Figure 12**). The incidence of transient hypoparathyroidism decreased

**Figure 12.** The status of inferior parathyroid glands after TT and CND. It was classified into four categories: C1, preserved in situ (vascularized); C2, autotransplanted (devascularized); C3, removed owing to infiltration by the tumor; and C4, not identified. The rate of inferior parathyroid gland preservation in situ was significantly improved on both

sides (P < 0.001) in the study group compared with the control group.

the ITA (between the innominate artery and ITA level).

26 Thyroid Disorders

**4. Clinical application results of "a layer of TBP"**

significantly from 35.0 to 7.2% (P < 0.001). In addition, the excised lymph nodes in the unilateral and bilateral CNDs were compared between the groups. The result showed that significantly more lymph nodes were removed in bilateral CND in the study group than in the control group; however, there was no difference in lymph nodes in unilateral CND between the groups (**Table 1**). Therefore, applying the proposed surgical concept improved the rate of inferior parathyroid gland preservation in situ and decreased the incidence of transient postoperative hypoparathyroidism, along with ensuring the completeness of lymph node dissection.


refined operational instruments. In this study, TT and CND were mostly performed under direct vision with the operator's headlight (mPack LL, HEINE Optometrik, Germany), and the first assistant's coordinated traction was emphasized; in addition, the use of a high-frequency electric knife with a needle-shaped head (Changzhou Yanling Electronic Equipment Co. Ltd., Jiangsu, China) and a small titanium ligating clip (Horizon; Weck Drive, Research Triangle Park, NC 27709, USA) are strongly recommended to preserve the parathyroid gland and its blood supply.

**Author details**

**References**

Lei Xie\*, Jianbiao Wang and Liang Zhou

Hangzhou, Zhejiang, P.R. China

1998;**22**:718-724

2015;**35**:731-736

\*Address all correspondence to: xiel@srrsh.com

Surgery. 1998 Oct;**22**(10):1098-1102 discussion 1103

Department of Head and Neck Surgery, Institute of Micro-Invasive Surgery of Zhejiang University, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University,

Inferior Parathyroid Gland Preservation In Situ during Central Neck Dissection for Thyroid…

http://dx.doi.org/10.5772/intechopen.78636

29

[1] Numano M, Tominaga Y, Uchida K, Orihara A, Tanaka Y, Takagi H. Surgical significance of supernumerary parathyroid glands in renal hyperparathyroidism. World Journal of

[2] Welbourn RB. The History of Endocrine Surgery. New York: Praeger Publishers; 1990 [3] Pattou F, Combemale F, Fabre S, Carnaille B, Decoulx M, etal WJL. Hypocalcemia following thyroid surgery: Incidence and prediction of outcome. World Journal of Surgery.

[4] Bhattacharyya N, Fried MP. Assessment of the morbidity and complications of total thyroidectomy. Archives of Otolaryngology – Head & Neck Surgery. 2002;**128**:389-392 [5] Abboud B, Sargi Z, Akkam M, Sleilaty F. Risk factors for post-thyroidectomy hypocalce-

[6] Gonçalves Filho J, Kowalski LP. Surgical complications after thyroid surgery performed in a cancer hospital. Otolaryngology and Head and Neck Surgery. 2005;**132**:490-494 [7] Giordano D, Valcavi R, Thompson GB, Pedroni C, Renna L, etal GP. Complications of central neck dissection in patients with papillary thyroid carcinoma: Results of a study

[8] Di Marino V, Argème M, Brunet C, Coppens R, Bonnoit J. Macroscopic study of the adult

[9] Cui Q, Li Z, Kong D, Wang K, Wu G. A prospective cohort study of novel functional types of parathyroid glands in thyroidectomy: In situ preservation or auto-transplantation? Medicine (Baltimore). Dec 2016;**95**(52):e5810. DOI: 10.1097/MD.0000000000005810

[10] Zhu JQ, Tian W, Xu ZG, Jiang KW, Sun H, Wang P, et al. The expert consensus of parathyroid glands protection during thyroidectomy. Chinese Journal of Practical Surgery.

[11] Thompson NW, Olsen WR, Hoffman GL. The continuing development of the technique

[12] Attie JN, Khafif RA. Preservationof parathyroid glands during total thyroidectomy.

mia. Journal of the American College of Surgeons. 2002;**195**:456-461

on 1087 patients and review of the literature. Thyroid. 2012;**22**:911-917

thymus. Surgical and Radiologic Anatomy. 1987;**9**:51-62

of thyroidectomy. Surgery. 1973;**73**:913-927

American Journal of Surgery. 1995;**130**:399

**6.** As mentioned earlier, when the RLN traverses between the ITA branches and the carotid artery, the paratracheal dissection can be divided into two parts according to the level of the ITA: a dissection cranial to the ITA (between the cricoid cartilage and ITA level) and one caudal to the ITA (between the innominate artery and ITA level), for completeness of dissection and RLN preservation (**Figure 11B**). Actually, the dissection between the cricoid cartilage and ITA level is a challenge because superior parathyroid gland and its blood supply from ITA and RLN are on this area. Although some surgeons declare that performing the dissection inferiorly from the trunk of ITA could achieve the equal completion of the dissection in safety [20, 21] because the metastatic lymph nodes are rarely found above the ITA trunk, the recurrence can be observed in this region between the cricoid cartilage and the ITA trunk. Therefore, the dissection in this region (between the cricoid cartilage and ITA level) should be emphasized, especially when the concept of "a layer of TBP" is performed. In addition, the usage of carbon nanoparticles, as a lymph tracer, can facilitate this procedure (not published).
