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A Closer Look at Laryngeal Nerves during Thyroid Surgery: A Descriptive Study of 584 Nerves.

Pradeep PV, Jayashree B, Harshita SS - Anat Res Int (2012)

Bottom Line: TZ was Grade 1 in 65.2%, Grade II in 25.1% and Grade III in 9.5%. 31.16% of the RLN passes through the LOB.Conclusions.A thorough knowledge of the laryngeal nerves and anatomical variations is necessary for safe thyroid surgery.

View Article: PubMed Central - PubMed

Affiliation: Department of Endocrine Surgery, Narayana Medical College & Superspeciality Hospital, Chinthareddypalem, Nellore 524002, India.

ABSTRACT
Morbidity after thyroidectomy is related to injuries to the parathyroids, recurrent laryngeal (RLN) and external branch of superior laryngeal nerves (EBSLN). Mostly these are due to variations in the surgical anatomy. In this study we analyse the surgical anatomy of the laryngeal nerves in Indian patients undergoing thyroidectomy. Materials and Methods. Retrospective study (February 2008 to February 2010). Patients undergoing surgery for benign goitres, T1, T2 thyroid cancers without lymph node involvement were included. Data on EBSLN types, RLN course and its relation to the TZ & LOB were recorded. Results. 404 thyroid surgeries (180 total & 224 hemithyroidectomy) were performed. Data related to 584 EBSLN and RLN were included (324 right sided & 260 left sided). EBSLN patterns were Type 1 in 71.4%, Type IIA in 12.3%, and Type IIB in 7.36%. The nerve was not seen in 4.3% cases. RLN had one branch in 69.34%, two branches in 29.11% and three branches in 1.36%. 25% of the RLN was superficial to the inferior thyroid artery, 65% deep to it and 8.2% between the branches. TZ was Grade 1 in 65.2%, Grade II in 25.1% and Grade III in 9.5%. 31.16% of the RLN passes through the LOB. Conclusions. A thorough knowledge of the laryngeal nerves and anatomical variations is necessary for safe thyroid surgery.

No MeSH data available.


Related in: MedlinePlus

ITA: Inferior thyroid artery. (A) depicts the left RLN deep to the ITA and (B) shows the right RLN superficial to the ITA.
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fig6: ITA: Inferior thyroid artery. (A) depicts the left RLN deep to the ITA and (B) shows the right RLN superficial to the ITA.

Mentions: Galen in second century A.D described the RLN [19]. Many surgeons including Billroth, Kocher, and Joll tried to avoid this nerve by dissecting away from it; however, some like Bier and Lahey preferred to expose those [1]. Even though the approach to the RLN varied it was realized that the nerve should not be injured. At present the exposure of the nerve is mandatory in all thyroid surgeries. The extra laryngeal branching of the RLN can lead to injuries to some of the branches of the RLN. In our dissection involving 584 RLN's majority had single branch (68.2% on the right side and 70.8% on the left); however, there were two or more branches in 31.42% on the right side and 29.2% on the left. With intraoperative neuromonitoring of the recurrent laryngeal nerve; Serpell et al. [20] had revealed RLN branching in 64.53%. Casella et al. [21] noticed that RLN had branches in 25.7% on the right side and 22.9% on the left. The motor fibers responsible for the adduction and abduction of the vocal cords are located in the anterior branches of the RLN. The RLN branching can be observed before and also after the crossing of the inferior thyroid artery across the nerve. We have observed that the bifurcation of the RLN commonly occurs distal to the crossing with the inferior thyroid artery and hence if the superior approach to identification of RLN is used, one of these branches may be injured. We therefore trace the branches to the trunk of the nerve in cases where we have to use the superior approach to RLN. Branched RLNs represent a risk factor for both temporary and permanent nerve palsy after surgery [22]. The relationship of the RLN to the ITA can vary. In our patients 64.3% is deep to the ITA, 8.2% passes in between the branches of ITA, and the remaining are superficial to the artery (Figure 6(A) and Figure 6(B)). Similarly Berlin [23] observed that more than 80% of the nerves was deep to the ITA.


A Closer Look at Laryngeal Nerves during Thyroid Surgery: A Descriptive Study of 584 Nerves.

Pradeep PV, Jayashree B, Harshita SS - Anat Res Int (2012)

ITA: Inferior thyroid artery. (A) depicts the left RLN deep to the ITA and (B) shows the right RLN superficial to the ITA.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3378964&req=5

fig6: ITA: Inferior thyroid artery. (A) depicts the left RLN deep to the ITA and (B) shows the right RLN superficial to the ITA.
Mentions: Galen in second century A.D described the RLN [19]. Many surgeons including Billroth, Kocher, and Joll tried to avoid this nerve by dissecting away from it; however, some like Bier and Lahey preferred to expose those [1]. Even though the approach to the RLN varied it was realized that the nerve should not be injured. At present the exposure of the nerve is mandatory in all thyroid surgeries. The extra laryngeal branching of the RLN can lead to injuries to some of the branches of the RLN. In our dissection involving 584 RLN's majority had single branch (68.2% on the right side and 70.8% on the left); however, there were two or more branches in 31.42% on the right side and 29.2% on the left. With intraoperative neuromonitoring of the recurrent laryngeal nerve; Serpell et al. [20] had revealed RLN branching in 64.53%. Casella et al. [21] noticed that RLN had branches in 25.7% on the right side and 22.9% on the left. The motor fibers responsible for the adduction and abduction of the vocal cords are located in the anterior branches of the RLN. The RLN branching can be observed before and also after the crossing of the inferior thyroid artery across the nerve. We have observed that the bifurcation of the RLN commonly occurs distal to the crossing with the inferior thyroid artery and hence if the superior approach to identification of RLN is used, one of these branches may be injured. We therefore trace the branches to the trunk of the nerve in cases where we have to use the superior approach to RLN. Branched RLNs represent a risk factor for both temporary and permanent nerve palsy after surgery [22]. The relationship of the RLN to the ITA can vary. In our patients 64.3% is deep to the ITA, 8.2% passes in between the branches of ITA, and the remaining are superficial to the artery (Figure 6(A) and Figure 6(B)). Similarly Berlin [23] observed that more than 80% of the nerves was deep to the ITA.

Bottom Line: TZ was Grade 1 in 65.2%, Grade II in 25.1% and Grade III in 9.5%. 31.16% of the RLN passes through the LOB.Conclusions.A thorough knowledge of the laryngeal nerves and anatomical variations is necessary for safe thyroid surgery.

View Article: PubMed Central - PubMed

Affiliation: Department of Endocrine Surgery, Narayana Medical College & Superspeciality Hospital, Chinthareddypalem, Nellore 524002, India.

ABSTRACT
Morbidity after thyroidectomy is related to injuries to the parathyroids, recurrent laryngeal (RLN) and external branch of superior laryngeal nerves (EBSLN). Mostly these are due to variations in the surgical anatomy. In this study we analyse the surgical anatomy of the laryngeal nerves in Indian patients undergoing thyroidectomy. Materials and Methods. Retrospective study (February 2008 to February 2010). Patients undergoing surgery for benign goitres, T1, T2 thyroid cancers without lymph node involvement were included. Data on EBSLN types, RLN course and its relation to the TZ & LOB were recorded. Results. 404 thyroid surgeries (180 total & 224 hemithyroidectomy) were performed. Data related to 584 EBSLN and RLN were included (324 right sided & 260 left sided). EBSLN patterns were Type 1 in 71.4%, Type IIA in 12.3%, and Type IIB in 7.36%. The nerve was not seen in 4.3% cases. RLN had one branch in 69.34%, two branches in 29.11% and three branches in 1.36%. 25% of the RLN was superficial to the inferior thyroid artery, 65% deep to it and 8.2% between the branches. TZ was Grade 1 in 65.2%, Grade II in 25.1% and Grade III in 9.5%. 31.16% of the RLN passes through the LOB. Conclusions. A thorough knowledge of the laryngeal nerves and anatomical variations is necessary for safe thyroid surgery.

No MeSH data available.


Related in: MedlinePlus