Anatomy of the sphenopalatine artery and its implications for transnasal neurosurgery.

BACKGROUND: The knowledge of sinonasal vasculature is inevitable in transnasal neurosurgery. We performed an anatomical study on the sphenopalatine artery from the perspective of skull base procedures. METHODOLOGY: To analyse the anatomical landmarks of the sphenopalatine artery, arterial skull corrosion casts (26 head halves) underwent endoscopic transnasal phantom surgery. Furthermore, we performed microsurgical dissection on formaldehyde-fixated cadavers with arterial perfusion (14 head halves) as well as studied Cone Beam CT-scans of anonymised patients and cadavers (115 head sides). RESULTS: In our cadaveric material, the sphenopalatine foramen is located at the transition of the superior and middle nasal meatus (95.0%) or in the superior nasal meatus (5.0%). It is the main entry point of the branches of the sphenopalatine artery into the nasal cavity. In most cadaveric cases (25.0%), at this level there are 2 branches superiorly and 1 vessel inferiorly to the ethmoid crest. An average of 2.4 vessels leave the sphenopalatine foramen superiorly to the ethmoid crest, 97.8% of them belong to the sphenopalatine arterys posterior septal branches. An average of 2.1 branches leave the sphenopalatine foramen inferiorly to the ethmoid crest; all of them belong to the posterior lateral nasal branches. There are no cases with a single artery at the plane of the sphenopalatine foramen. We describe a triangular bony structure bordering the sphenopalatine foramen anteriorly which is built up by the palatine and ethmoid bone as well as the maxilla. According to the radiographic studies, this triangular prominence is surrounded superiorly by a posterior ethmoid cell (57.4%), the sphenoid sinus (41.7%) or the orbit (0.9%) with a varying contribution of the superior nasal meatus; inferolaterally by the maxillary sinus (98.3%) or the pterygopalatine and infratemporal fossa (1.7%) and inferomedially by the middle nasal meatus. The medial vertex of the bony triangle corresponds to the ethmoid crest of the palatine bone. In transnasal endoscopic surgery, the posterior lateral nasal branches of the sphenopalatine artery appear at the triangle's inferomedial edge, the posterior septal branches emerge at its superior edge. CONCLUSIONS: The triangular bony structure is a landmark to find and differentiate the posterior lateral nasal and posterior septal branches of the sphenopalatine artery and to identify the sphenoid sinus.

Suitability of a preserved human cadaver model for the simulation of facemask ventilation, direct laryngoscopy and tracheal intubation: a laboratory investigation.

BACKGROUND: Using fresh or formalin-embalmed cadavers has not been generally accepted for the purposes of teaching airway management. We investigated whether cadavers 'preserved according Thiel's embalming method' (PATEM) are suitable for the simulation of facemask ventilation and tracheal intubation by direct laryngoscopy. METHODS: This observational cluster sampling, controlled simulation study, included eight PATEM cadavers and eight manikins in two clusters. Twenty experienced anaesthetists were randomly assigned to execute 80 facemask ventilations and 80 tracheal intubations in both groups. The ease of facemask ventilation was the primary endpoint. The secondary endpoint was the composite outcomes of laryngoscopy and tracheal intubation. RESULTS: The success rate at the first attempt at mask ventilation was 74% (59/80 attempts) on cadavers and 41% (33/80 attempts) on manikins (P<0.0001). Twenty one subjects received an oral airway in both groups and succeeded in facemask ventilation 20 times on cadavers and four times on manikins (P=0.004). Two-handed technique mask ventilation was required 24 times on manikins and once on cadavers (P=0.0016). In one attempt on a manikin the mask ventilation was impossible. Poor laryngeal view (Cormack-Lehane grade 3) occurred 14 times among cadavers (17.5%) and once in manikins (1.25%) (P=0.007), whereas difficulties in tracheal intubation were encountered 16 times in cadavers (20%) vs 17 times in manikins (21.25%) (P=0.84). In a subjective evaluation the participants preferred the cadaver model over the manikins (P<0.0001). CONCLUSIONS: PATEM cadavers were better suited for facemask ventilation and provided a more realistic environment for laryngoscopy and tracheal intubation than the studied manikins.