Jugular foramen anatomy in lateral skull base paraganglioma surgery

In this article we present the surgical approaches to the temporal bone paraganglioma based on the anatomical studies. Objective. To detalize the anatomy of the jugular foramen according to the comparison of cadaver dissections findings and the CT scans data that were performed before the dissections, for improvement of quality of treatment of patients with temporal bone paraganglioma (Fisch type C). Material and methods. The data of CT scans and the steps of the approaches to the jugular foramen (retrofacial and infratemporal approaches with opening of jugular bulb and identification of the anatomical structures of jugular foramen) were analyzed on 10 cadaver heads, 20 sides. Clinical implementation was demonstrated in case of temporal bone paraganglioma type C. Results. Based on the detail study of the CTs data we revealed the individual features of the temporal bone structures. Due to the results of 3D rendering the average length of the jugular foramen in anterior-posterior direction was 10.1 mm. The length of vascular part was larger than the nervous part. The posterior part had the bigger height wherein the shortest part we detected between jugular ridges, which in some cases caused the dumbbell shape of jugular foramen. According to 3D multiplanar reconstruction the distances between jugular crests (3.0 mm) had the lowest measures and the largest was between internal auditory canal (IAC) and jugular bulb (JB) (8.01mm). At the same time, one of the largest variations of values was also identified between IAC and JB (from 4.39 to 9.84 mm). The distance between the facial nerve in the mastoid segment and JB was variable (from 3.4 to 10.2 mm) and determined by the volume and position of the JB. The results of the dissection corresponded to the measurements according to the CT scans, taking into account the 2-3 mm error due to the massive removal of temporal bone during performing of surgical approaches. Conclusion. The detailed knowledge of the surgical anatomy of the jugular foramen based on a thorough analysis of preoperative CT data is the key to an adequate surgical tactic for the removal of different types of temporal bone paraganglioma while preserving the function of vital structures and the quality of life. A larger study on the big data is needed to determine the statistical relationship between the volume of JB and the size of the jugular crest; the correlation between the dimensions of jugular crests and the tumor invasion in the anterior part of the jugular foramen.