Middle Cranial Fossa Approach: Anatomical Study on Skull Base Triangles as a Landmark for a Safe Anterior Petrosectomy.

Objective The Kawase approach provides access to the petroclival and posterior cavernous sinus regions, cerebellopontine angle, and upper basilar artery territory. Nevertheless, it remains one of the most challenging approach for neurosurgeons, due to the considerable related morbidity and mortality. The goal of this study was to evaluate the relationship between anatomical landmarks and their possible variations, and to measure the extension of the Kawase space, to define the reliability of these landmarks while performing an anterior petrosectomy. Design Using eight cadaveric specimens (15 sides), an anatomical dissections and extradural exposure of the Kawase area were performed. Settings A two-step analysis of the distances between the mandibular branch of the trigeminal nerve (V3) and the structures at risk of iatrogenic damage was performed. Main outcome measures We measured the distance between V3 and the basal turn of the cochlea, and between V3 and the internal acoustic canal (IAC), analyzing the limits of bone resection without causing hearing damage. Results We analyzed eight cadaveric (15 sides) formalin-fixed heads injected with colored silicone: four males and four females of Caucasian race (mean age: 73.83 years). We found a mean distance of 10.46 ± 1.13 mm between the great superficial petrous nerve (GSPN) intersection with V3 and the basal turn of the cochlea, and of 11.92 ± 1.71 mm between the origin point of V3 from the Gasserian ganglion and the fundus of the IAC. Conclusion The knowledge of the safe distance between the most applicable anatomic landmarks and the hearing structures is a practical and useful method to perform this approach reducing related comorbidity.

Anatomical Correlation Between Nasal Vascularisation and the Design of the Endonasal Pedicle Flaps.

Arteries that supply the nasal septum and the lateral nasal wall include vessels that originate from the external carotid artery and from the internal carotid artery. A variety of local endonasal pedicle flaps can be used in different anatomical areas for endoscopic skull base reconstruction. The main flaps are based on terminal branches of the sphenopalatine artery and on anterior ethmoidal artery. This study will describe the anatomy of these vessels and their relationship with the main flaps.

Surgical Anatomy of the Medial Wall of the Orbit in 14 Human Cadavers.

Objective The aim of our study is to present the anatomical landmarks to perform an endoscopic endonasal approach to the medial wall of the orbit (EEAMO). Material and Methods We performed 14 complete nasal and orbital endoscopic dissections in 7 adult cadaveric heads. Results The EEAMO provides a surgical corridor between the medial rectus muscle superiorly and the inferior rectus muscle inferiorly .The mean distance between the ethmoidal crest and medial rectus muscle was 1.5 cm (range, 1.3-1.9 cm). The width of the medial rectus muscle was 1.2 cm (range, 1-1.5 cm). The main vascular structure in this retrobulbar space was the ophthalmic artery that crosses over the optic nerve in 86% of the cases. In its intraorbital route, the anterior ethmoidal artery and the ethmoidal nerves were situated inferior to the superior oblique muscle in all cases. The posterior ethmoidal artery was found superior to it. We could identify the inferior division of the oculomotor nerve in this surgical approach. Conclusions The EEAMO allows adequate exposure of the space between the medial rectus muscle and the inferior rectus muscle. The location of the ethmoidal crest of the palatine bone, and its relationship with the medial rectus muscle, is a useful anatomical landmark for this surgical approach.

Anatomical and surgical study of the sphenopalatine artery branches.

The sphenopalatine artery gives off two main branches: the posterior lateral nasal branch and the posterior septal branch. From 2007 to 2012 17 patients were treated with cauterization and/or ligature of the sphenopalatine artery with endonasal endoscopic approach. 90 nasal dissections were performed in 45 adult cadaveric heads. We evaluated the number of branches emerging from the sphenopalatine foramen and the presence of an accessory foramen. In the surgery group, we observed a single trunk in 76% of the patients (13/17) and a double trunk in 24% (4/17). We found an accessory foramen in four cases. We obtained a successful result in bleeding control in 88% of the cases. In the cadaver dissection group, 55 nasal cavities had a single arterial trunk (61%), 30 had 2 arterial trunks (33%) and in only 5 nasal fossae we observed 3 arterial trunks (6%). We were able to dissect four accessory foramina. We suggest that in most cases only one or two branches are found in the sphenopalatine foramen.