J Clin Med Res

Journal of Clinical Medicine Research, ISSN 1918-3003 print, 1918-3011 online, Open Access

Article copyright, the authors; Journal compilation copyright, J Clin Med Res and Elmer Press Inc

Journal website https://www.jocmr.org

Review

Volume 12, Number 10, October 2020, pages 640-646

The Anatomical Relationship of Inferior Thyroid Artery and Recurrent Laryngeal Nerve: A Review of the Literature and Its Clinical Importance

Figure 1. The anatomical relationships between the RLN and the ITA. RLN: recurrent laryngeal nerve; ITA: inferior thyroid artery.

Figure 2. Flow diagram according to PRISMA guidelines. PRISMA: the preferred reporting items for systemic reviews and meta-analyses.

Figure 3. Forest plot for the right-sided prevalence of the RLN anterior to ITA. RLN: recurrent laryngeal nerve; ITA: inferior thyroid artery.

Figure 4. Forest plot for the left-sided prevalence of the RLN anterior to ITA. RLN: recurrent laryngeal nerve; ITA: inferior thyroid artery.

Figure 5. Forest plot for the right-sided prevalence of the RLN posterior to ITA. RLN: recurrent laryngeal nerve; ITA: inferior thyroid artery.

Figure 6. Forest plot for the left-sided prevalence of the RLN posterior to ITA. RLN: recurrent laryngeal nerve; ITA: inferior thyroid artery.

**Table 1.** The Included Studies and the Prevalence of Each Type of RLN to ITA Relationship
Study	Type of patients	Number of RLN	RA	LA	A	RP	LP	P	B
C: cadavers; IP: intraoperative finding; RLN: recurrent laryngeal nerve; ITA: inferior thyroid artery; RA: right anterior, LA: left anterior, A: anterior, RP: right posterior, LP: left posterior, P: posterior, B: between.
She et al, 2005 [1]	C	99			30.3%			38.4%	31.3%
Uen et al, 2006 [2]	C	120	20.0%	8.33%	14.2%	61.67%	70.0%	65.8%	20.0%
Kuo et al, 2006 [3]	C	91			20.9%			59.3%	19.7%
Sultana et al, 2006 [4]	C	120			27.5%			30.8%	40.0%
Makay et al, 2008 [5]	IP	487	23.8%	18.9%	21.4%	63.66%	70.6%	67.2%	12.9%
Altorjay et al, 2009 [6]	IP	1,023	45.6%	15.4%	30.5%	47.70%	76.1%	61.9%	7.6%
Lee et al, 2009 [7]	C	110	40.0%	23.6%	31.8%	34.55%	56.4%	45.4%	22.7%
Sun et al, 2010 [8]	IP	566			1.94%			64.8%	31.9%
Kaisha et al, 2011 [9]	C	146			36.9%			50.0%	12.3%
Matubis et al, 2011 [10]	C	108			28.7%			59.3%	11.11%
Zhang et al, 2011 [11]	C	80			21.3%			40.0%	36.6%
Lu et al, 2012 [12]	C	100			22.0%			43.0%	35.0%
Asgharpour et al, 2012 [13]	C	246			32.9%			35.8%	31.3%
Tang et al, 2012 [14]	C	160	75.0%	7.50%	41.2%	10.00%	86.3%	48.1%	6.25%
Dai et al, 2014 [15]	IP	342			30.9%			62.9%	6.14%
Ozguner et al, 2014 [16]	C	400	11.5%	7.00%	9.25%	42.00%	65.0%	53.5%	5.00%

Table 1. The Included Studies and the Prevalence of Each Type of RLN to ITA Relationship

Study

Type of patients

Number of RLN

C: cadavers; IP: intraoperative finding; RLN: recurrent laryngeal nerve; ITA: inferior thyroid artery; RA: right anterior, LA: left anterior, A: anterior, RP: right posterior, LP: left posterior, P: posterior, B: between.

She et al, 2005 [1]

30.3%

38.4%

31.3%

Uen et al, 2006 [2]

120

20.0%

8.33%

14.2%

61.67%

70.0%

65.8%

20.0%

Kuo et al, 2006 [3]

20.9%

59.3%

19.7%

Sultana et al, 2006 [4]

120

27.5%

30.8%

40.0%

Makay et al, 2008 [5]

487

23.8%

18.9%

21.4%

63.66%

70.6%

67.2%

12.9%

Altorjay et al, 2009 [6]

1,023

45.6%

15.4%

30.5%

47.70%

76.1%

61.9%

7.6%

Lee et al, 2009 [7]

110

40.0%

23.6%

31.8%

34.55%

56.4%

45.4%

22.7%

Sun et al, 2010 [8]

566

1.94%

64.8%

31.9%

Kaisha et al, 2011 [9]

146

36.9%

50.0%

12.3%

Matubis et al, 2011 [10]

108

28.7%

59.3%

11.11%

Zhang et al, 2011 [11]

21.3%

40.0%

36.6%

Lu et al, 2012 [12]

100

22.0%

43.0%

35.0%

Asgharpour et al, 2012 [13]

246

32.9%

35.8%

31.3%

Tang et al, 2012 [14]

160

75.0%

7.50%

41.2%

10.00%

86.3%

48.1%

6.25%

Dai et al, 2014 [15]

342

30.9%

62.9%

6.14%

Ozguner et al, 2014 [16]

400

11.5%

7.00%

9.25%

42.00%

65.0%

53.5%

5.00%

**Table 2.** The Number of Studies Included, the Prevalence Estimate and the Statistical Heterogeneity According to Higgins I² Statistics
Variables	Number of studies (number of nerves)	Anterior % (95% CI)	I² % (95% CI)	Posterior % (95% CI)	I² % (95% CI)	Between % (95% CI)	I² % (95% CI)
CI: confidence interval.
Overall	16 (4,198)	23.9 (16.8 - 31.7)	96.7 (95.6 - 97.4)	52.1 (46.5 - 57.6)	91.7 (88.1 - 94.2)	18.9 (13.0 - 25.6)	96.1(94.8 - 97.1)
Right	6 (955)	16.5 (8.96 - 25.7)	95,9 (93.4 - 97.5)	20.8 (14.2 - 28.2)	93.1 (87.7 - 96.1)
Left	6 (996)	06.5 (4.31 - 9.10)	77.2 (49.3 - 89.7)	35.7 (32.6 - 38.9)	52.1 (0 - 80.1)

Table 2. The Number of Studies Included, the Prevalence Estimate and the Statistical Heterogeneity According to Higgins I² Statistics

Variables

Number of studies (number of nerves)

Anterior % (95% CI)

I² % (95% CI)

Posterior % (95% CI)

I² % (95% CI)

Between % (95% CI)

I² % (95% CI)

CI: confidence interval.

Overall

16 (4,198)

23.9 (16.8 - 31.7)

96.7 (95.6 - 97.4)

52.1 (46.5 - 57.6)

91.7 (88.1 - 94.2)

18.9 (13.0 - 25.6)

96.1(94.8 - 97.1)

Right

6 (955)

16.5 (8.96 - 25.7)

95,9 (93.4 - 97.5)

20.8 (14.2 - 28.2)

93.1 (87.7 - 96.1)

Left

6 (996)

06.5 (4.31 - 9.10)

77.2 (49.3 - 89.7)

35.7 (32.6 - 38.9)

52.1 (0 - 80.1)