Duplicated Vagus Nerve in Adolescence: Case Report and Review of Literature.

BACKGROUND: Vagus nerve stimulation (VNS) has become an increasingly popular procedure for the treatment of epilepsy and depression. Significant complications or side effects associated with VNS surgery may result from either the inadvertent direct injury to the vagus nerve as part of the surgical approach, placement of the electrode, or the concomitant stimulation of vagal efferent fibers. To mitigate these effects, the recognition of anatomic variants that may place the nerve at increased risk is necessary. CASE DESCRIPTION: During microsurgical dissection of the carotid sheath for the implantation of a vagus nerve stimulator in a 17-year-old male patient with refractory epilepsy, additional nonidentified nerve tissue was found running parallel to the vagus nerve. These fibers were two thirds of the thickness of the vagus nerve and ran medial to it, from the most superior to the most inferior aspect of the carotid sheath dissection, found at a distance of at least 4 cm in a craniocaudal direction. This duplicated nerve did not appear to branch from the vagal trunk nor exit the sheath but rather paralleled the course of the vagus nerve. The parallel course and the proximity of the unidentified nerve make this structure likely to be a duplicated vagus nerve. CONCLUSIONS: This is the first reported case of cervical vagus nerve duplication presented in the literature. Surgeons performing VNS implantations should be cognizant of this potential anomaly in order to avoid inadvertent injury to the nerve.

Variations in the course of the cervical vagus nerve on thyroid ultrasonography.

BACKGROUND AND PURPOSE: Only 1 ultrasonography study that described the variation of the VN had been published at the time our research was begun. The purpose of this study was to evaluate the incidence and type of variation in the course of the cervical VN on thyroid ultrasonography. MATERIALS AND METHODS: From August 2009 to September 2010, 163 consecutive patients were evaluated by sonography for the screening and characterization of thyroid nodules (mean age, 49.0 ± 14.4 years, male:female, 20:143). Two types of variation were defined as follows: 1) anterior variation, when the course of the VNs changed from the typical location to an anterior location in front of the CCA; and 2) medial variation, when the course of the VNs changed from the typical location to a location medial to the CCA (between CCA and thyroid gland). The incidence of the each variation was studied. RESULTS: Variation in the course of the VN occurred in 5.5% (18/326) of cases. The anterior variation was observed in 4.3% (14/326, right:left = 4:10), and the medial variation was observed in 1.2% (4/326, right:left = 3:1). For both variations, the VN was close to or nearly abutted the thyroid gland after it changed course. CONCLUSIONS: Variation in the course of the cervical VN could be assessed by ultrasonography. Two variations were observed in 5.5% of cases. The anterior variation was more common than the medial variation.

A "pilot light" of the right non-recurrent laryngeal nerve.

Total thyroidectomy was performed in a 53-year-old male, with Graves-Basedow's disease. At surgery, the vagus nerve was found to be located medially to the carotid artery associated with a non-recurrent laryngeal nerve arising directly from the cervical vagus: this association has never been described in the literature. These results indicate that a medial location of the vagus nerve may be considered as a "pilot light" of the non-recurrent laryngeal nerve.

Unusual origin of the ansa cervicalis observed during carotid endarterectomy.

The surgical approach of the carotid artery for carotid endarterectomy demands knowledge of normal anatomy and anatomic variation. During carotid endarterectomy, a rare anatomic variant of the origin of the upper root of the ansa cervicalis was found. Contrary to commonly found anatomy, no upper root of the ansa cervicalis originating from the hypoglossal nerve was found. Instead, what seemed to be the ansa cervicalis originated from the vagus nerve and passed over the carotid bifurcation, branching to the infrahyoid muscles. Transection of this ansa cervicalis, for the purpose of good exposure, had no functional or cosmetic consequences.

The myenteric plexus of the esophagus is abnormal in an experimental congenital diaphragmatic hernia model.

BACKGROUND/AIM: Infants surviving congenital diaphragmatic hernia (CDH) suffer from anatomical and functional esophageal abnormalities. Previous work in the nitrofen animal model of CDH demonstrated malformations in neural crest-derived structures, including the vagus and recurrent laryngeal nerves. The aim of the present study was to assess whether the esophageal myenteric plexus is abnormal in rats with CDH. METHODS: We used the nitrofen-induced CDH fetal rat model. Two sections of the proximal, medium and distal esophagus from both groups were processed for immunohistochemical staining with anti-neuron specific enolase and anti-S-100 antibodies; the number of stained areas was recorded for each group. Whole-mount preparations of the entire esophagus of Control and CDH animals were histochemically stained for acetylcholinesterase; the density and area of the ganglia and the number of cells/ganglia were determined. Comparisons between groups were made by standard statistical methods. RESULTS: The number of immunohistochemically stained areas in transversal sections were decreased in CDH animals for anti-enolase (11.5+/-6.06 vs. 1.93+/-1.49, control vs. CDH, p<0.001) and anti S-100 antibodies (8.57+/-4.1 vs. 4.06+/-2.82, p<0.001). In whole-mount preparations the number of ganglia per high power field (35.16+/-6.57 vs. 29.29+/-10.26, p<0.05), the number of cells per ganglia (11.85+/-3.52 vs. 2.28+/-4.61, p<0.0001) and the relative area of the ganglia (0.35+/-0.32 vs. 0.18+/-0.42%, p<0.001), were also significantly decreased in CDH animals compared with Controls. CONCLUSIONS: Esophageal intrinsic innervation is defective in rat fetuses with CDH. If patients with CDH bear the same anomalies, this may explain some of their esophageal motility disorders. Finally, these findings support the concept of neural crest involvement in the pathogenic pathways of CDH.

Anomalous intrathoracic left vagus and recurrent laryngeal nerve course.

An anomalous course of the vagus nerve is an extremely rare congenital anomaly. We report the case of a 59-year-old man who had left lung cancer. We performed a left upper lobectomy and mediastinal lymphadenectomy, paying attention to the pathway of the left vagus nerve, which had an anomalous course passing anteriorly to the left pulmonary trunk between the apical and anterior branches. The left recurrent laryngeal nerve hooked around the lower border of the apical branch of the left pulmonary artery.

Perturbation of hoxb5 signaling in vagal neural crests down-regulates ret leading to intestinal hypoganglionosis in mice.

BACKGROUND & AIMS: The enteric nervous system (ENS) controls intestinal peristalsis, and defective development of this system results in hypo/aganglionosis, as seen in Hirschsprung's disease. In the embryo, vagal neural crest cells (NCC) migrate and colonize the intestine rostrocaudally then differentiate into the ganglia of the ENS. Vagal NCC express the homeobox gene Hoxb5, a transcriptional activator, in human and mouse, so we used transgenic mice to investigate the function of Hoxb5 and the receptor tyrosine kinase gene Ret, which is affected in many patients with Hirschsprung's disease, in ENS development. METHODS: We perturbed the Hoxb5 pathway by expressing a chimeric protein enb5, in which the transcription activation domain of Hoxb5 was replaced with the repressor domain of the Drosophila engrailed protein (en), in vagal NCC. This enb5 transcriptional repressor competes with wild-type Hoxb5 for binding to target genes, exerting a dominant negative effect. RESULTS: We observed that 30.6% +/- 2.3% of NCC expressed enb5 and that these enb5-expressing NCC failed to migrate to the distal intestine. A 34%-37% reduction of ganglia (hypoganglionosis) and slow peristalsis and, occasionally, absence of ganglia and intestinal obstruction were observed in enb5-expressing mice. Ret expression was markedly reduced or absent in NCC and ganglia, and enb5 blocked Hoxb5 induction of Ret in neuroblastoma cells. CONCLUSIONS: Our data indicate that Ret is a downstream target of Hoxb5 whose perturbation causes Ret haploinsufficiency, impaired NCC migration, and hypo/aganglionosis, suggesting that Hoxb5 may contribute to the etiology of Hirschsprung's disease.

[Diagnostic complexities and anatomical surprises in a case of thyroid surgery for papillary carcinoma]. / Complessità diagnostiche e sorprese anatomiche in un caso di chirurgia tiroidea per carcinoma papillare.

We present the case of a male patient who needed surgery for a large undefined submandibular schwannoma and a small contralateral thyroid carcinoma associated with cervical lymph nodes of a dubious nature. During the operative procedure all the pathological conditions were resolved, with some remarkable surprises. A non-functioning parathyroid adenoma was found and removed. A fairly unusual anatomical complication was also detected with regard to the right inferior laryngeal nerve, i.e. an anastomotic branch connecting the main trunk to the vagus nerve.

The vagus and recurrent laryngeal nerves in experimental congenital diaphragmatic hernia.

BACKGROUND: The etiology of the anatomic and functional abnormalities of the esophagus in infants surviving congenital diaphragmatic hernia (CDH) remains unclear. We showed previously that fetal rats with CDH have malformations of neural crest-derived structures. The aim of this study was to examine the anatomy of the vagus and the recurrent laryngeal nerves, both of neural crest origin, in rats with CDH. METHODS: We used the nitrofen-induced CDH fetal rat model. Nine control fetuses from four dams and nine fetuses with CDH from seven dams were included in this study. Embryos were fixed in formalin and a thoracic block from the larynx to tracheal bifurcation was serially sectioned in the horizontal plane. One in every ten sections was stained with hematoxylin and eosin. The image was digitalized using biological software (TDR-3dbase). Vagus and recurrent laryngeal nerves, trachea, esophagus and the great vessels were examined. In order to obtain the three-dimensional reconstructions, 90-120 consecutive images were used. RESULTS: In comparison with controls there were striking abnormalities of the vagus and the recurrent laryngeal nerves in fetuses with CDH: (1) absence of the left (2/9) or right (2/9) vagus nerves; (2) absence of the left (3/9) or right (3/9) recurrent laryngeal nerves; (3) marked hypoplasia of the trunk of the vagus (2/9); (4) deviations of their normal course and change of normal anatomical relationships into the mediastinum (2/9); and (5) abnormal branching of the lower portion of the vagus (1/9). CONCLUSIONS: Rat fetuses with CDH have anomalies of the vagus and recurrent laryngeal nerves that support the concept of a neural crest involvement in the origin of this malformation. 3-D reconstructions allow a detailed analysis and provide a precise insight into the real anatomy. These observations may explain esophageal motility disorders in CDH.

[The right inferior laryngeal nerve with a non-recurrent course]. / Il nervo laringeo inferiore destro a decorso non ricorrente.

Two cases of a right non-recurrent laryngeal nerve were encountered during the performance of 992 thyroid operations. In its abnormal non-recurrent course the nerve passes transversely from under the carotid sheat hand takes a position which is at right-angles to the normal recurrent laryngeal nerve.

The vagus and recurrent laryngeal nerves in the rodent experimental model of esophageal atresia.

BACKGROUND: After surgical correction of their esophageal atresia and tracheoesophageal fistula (EA-TEF), many patients exhibit evidence of esophageal dysmotility. Controversy exists as to whether the esophageal motility disorders result from denervation caused by surgery or from an inherent abnormal innervation of the esophagus. METHODS: The present study used an Adriamycin-induced EA-TEF fetal rat model to trace the course and branching of both the vagus and recurrent laryngeal nerves. Abnormalities observed in EA-TEF rat fetuses include: (1) fewer branches from both recurrent laryngeal nerves; (2) deviation of the left vagus from its normal course below the aorta, passing behind the fistula to approach and join with the right vagus to form a single nerve trunk on the right side of the esophagus; (3) relatively few branches from the single vagal nerve trunk (composed of fibers of the left and the right vagus) on the surface of the lower esophagus. CONCLUSIONS: Fetuses affected by EA-TEF have inherent abnormalities in the course and branching pattern of the vagus nerves as they descend through the thorax, culminating in a deficient extrinsic nerve fiber plexus in the lower esophagus. These observations may account for the esophageal motility disorders seen in patients who have EA-TEF even before surgical intervention.