A case of unilateral fenestration of the external jugular vein, through which the cervical branch of the facial nerve passes

Abstract

The external jugular vein (EJV) is being utilized increasingly as the recipient vein in head and neck free tissue transfers, and for cannulation in order to conduct diagnostic procedures or intravenous therapies. Knowledge of variations in its structure or pathway are therefore important. Various authors have described phlebectasia (Hermans 1991; Turan-Ozdemir et al. 2004), saccular aneurysm (Verbeeck et al. 1997), duplication of the EJV (Comert and Comert 2009), and anastomosis between the EJV and internal jugular vein (IJV) (Chalian et al. 2001). We report on unilateral EJV fenestration, through which the cervical branch of the facial nerve passes—an entity that has not been reported previously. During a course in applied clinical anatomy for dental students and dissection of the neck of a 75-year-old female cadaver, a large fenestration of the EJV was observed on the left side after removing the skin from the platysma muscle (Fig. 1). The anterior division of the retromandibular vein was absent. The entire retromandibular vein joined the posterior auricular vein to form the EJV, which continued downwards and bifurcated into a medial and lateral branch, half-way between the hyoid bone and the upper margin of thyroid cartilage, and reunited again just before penetrating the deep fascia 2.5 cm above the clavicle. There was no venous dilatation before or after the fenestration. The fenestrated segment of the EJV was large: 6 cm in length. The cervical branch of the facial nerve passed through the fenestrated EJV, running superficially to its medial and deep to its lateral branch before entering the platysma muscle. A communicating vein (CV) connected the medial branch of the EJV and the anterior jugular vein (AJV), which was formed by a union of the facial vein and the submental vein. The EJV entered the subclavian vein on the deep surface of the sternocleidomastoid muscle. The AJV emptied into the EJV near the junction of the EJV with the subclavian vein. No variation of the IJV was observed. The veins on the right side of the neck showed no significant variations. In many of the craniocervical arteries, divisions of the vasculature have been described, but venous fenestrations only rarely so (Towbin and Kanal 2004). Divisions (fenestrations or duplications) of the IJV are estimated to occur in as much as 0.4 % of the population (Prades et al. 2002). We could find only one publication on EJV division in the available literature (Comert and Comert 2009). In order to avoid confusion between the terms duplication and fenestration, which are used interchangeably in the literature, Downie et al. (2007) suggested that the term duplication be limited to those cases in which the branches of the anomalous vessel remain separate over the entire course, whereas the term fenestration should be used for those cases in which the branched vessel reunites into a single normal vessel. Comert and Comert (2009) reported an EJV duplication observed during neck surgery. No nerve passed through the duplicated part of the vessel. Since the duplicated segment was described in the middle part of the EJV, which reunited again into a single stem, the anomaly concerned was in fact fenestration and not duplication according to the reclassification proposed by Downie et al. (2007). It has been postulated that vessel duplication may be due to derangement from early development between the 3rd and 6th gestational weeks (Rossi and Tortori-Donati 2001). IJV duplication is usually reported in association with phlebectasia, suggesting abnormal development of the E. Cvetko (&) Institute of Anatomy, Medical Faculty, University of Ljubljana, Korytkova 2, 1000 Ljubljana, Slovenia e-mail: erika.cvetko@mf.uni-lj.si