Hua Xiaoyang, Diggelmann Henry, Jalukar Vishram, Turek Joseph W, Pagedar Nitin A
1 Department of Otolaryngology-Head and Neck Surgery, University of Iowa Hospitals and Clinics, Iowa City, Iowa, USA.
2 Department of Otolaryngology-Head and Neck Surgery, Mercy North Iowa Medical Center, Mason City, Iowa, USA.
Ann Otol Rhinol Laryngol. 2018 Feb;127(2):124-127. doi: 10.1177/0003489417744318. Epub 2017 Dec 4.
Left nonrecurrent laryngeal nerve (LNRLN) is an extremely rare anatomic variant. The development of such anatomic variation requires the regression of both the fourth (aortic arch) and sixth (ductus arteriosus, DA) arches on the left side. Preoperative prediction of this variant is difficult but might reduce risk of nerve injury.
A 34-year-old female was indicated for thyroidectomy for a 2.4 cm follicular neoplasm and Graves' disease. Due to a positive medical history of 22q11.2 microdeletion and unexplained left vocal cord paralysis, a preoperative chest computed tomography (CT) scan was obtained and revealed a right-sided aorta (RSA) and aberrant left subclavian artery (ALSA) without Kommerell's diverticulum. A left-sided NRLN was then highly suspected.
Thyroidectomy was performed under general anesthesia with the utilization of intraoperative laryngeal nerve monitoring. A LNRLN was confirmed intraoperatively.
Right-sided aorta and ALSA indicate embryologic regression of the left fourth primitive aortic arch. The absence of Kommerell's diverticulum at the origin of the ALSA indicates the lack of high-pressure blood flow from the pulmonary artery to the ALSA through the ductus arteriosus during embryogenesis, suggesting the embryologic regression of the left sixth primitive aortic arch. The presence of all 3 radiologic features thus highly suggests the possibility of a LNRLN.
左侧非返喉返神经（LNRLN）是一种极其罕见的解剖变异。这种解剖变异的发生需要左侧第四（主动脉弓）和第六（动脉导管，DA）弓的退化。术前预测这种变异很困难，但可能会降低神经损伤的风险。
一名34岁女性因2.4 cm滤泡性肿瘤和格雷夫斯病接受甲状腺切除术。由于有22q11.2微缺失的阳性病史和不明原因的左侧声带麻痹，术前进行了胸部计算机断层扫描（CT），结果显示为右侧主动脉（RSA）和异常左锁骨下动脉（ALSA），无Kommerell憩室。因此高度怀疑存在左侧非返喉返神经。
在全身麻醉下利用术中喉返神经监测进行了甲状腺切除术。术中证实存在左侧非返喉返神经。
右侧主动脉和异常左锁骨下动脉表明左侧第四原始主动脉弓的胚胎学退化。异常左锁骨下动脉起始处无Kommerell憩室表明胚胎发育过程中缺乏从肺动脉通过动脉导管向异常左锁骨下动脉的高压血流，提示左侧第六原始主动脉弓的胚胎学退化。因此，所有这三种影像学特征的存在高度提示存在左侧非返喉返神经的可能性。
