| Objective To study the skull base related to the nasal parapharyngeal space which the endoscopic nasopharyngectomy for salvage in nasopharyngeal carcinoma. To research the relationship between important anatomical structures of skull base endoscopic nasopharyngectomy for salvage in nasopharyngeal carcinoma, and to find the anatomical landmarks in order to guide the clinic surgeries.Methods We choose eight adult cadaver specimens (16 sides) with 10% formalin fixed, and we operate arterial red colored latex injection and venous blue colored latex injection. After we did screw CT scan of the specimens, we expose full nasal sinuses, and simulate three kind of surgeries: middle nasal meatus or posterior wall of the maxillary sines approach to the pterygopalatine fossa/ infratemporal fossa, transpterygoid (transpterygopalatine-fossa ) approach in endoscopic skull base surgery, and endoscopic nasopharyngectomy for salvage in nasopharyngeal carcinoma. We dissected the skull base of nasopharynx, parapharyngeal space and adjacent areas, and we identified important anatomical landmarks and relationship between them. We measure the distance between columella nasi and the boundary of vidian nerve and anterior genu of internal carotid artery, the distance between columella nasi and eustachian tube isthmus, the distance between columella nasi and internal carotid artery, and the distance between eustachian tube isthmus and internal carotid canal external aperture. We use CT to measure the length of vidian canal, the length between the sagittal line of opisthognathous of vidian canal and inner margin of carotid canal, the shortest distance between eustachian tube isthmus and internal carotid canal external aperture, the distance between opisthognathous of vidian canal and eustachian tube isthmus, and the distance between opisthognathous of vidian canal and carotid canal.Results①The frequency of vidian canal influenced by the sphenoid pneumatization. The vidian canal pointed to the foramen lacerum permanently, thus, we can locating anterior genu of internal carotid artery by chasing the vidian nerve which surrounded the vidian canal, and we can stripping the fibrosa cartilage of the foramen lacerum beneath the vidian nerve without injured the internal carotid artery. The relationship between the foramen rotundum and vidian canal in pterygopalatine fossa is stable. We can locate horizontal segment of the internal carotid artery, the anterior border of cavernous sinus and Meckel's cave by chasing maxillary nerve and vidian canal nerve in endoscopic transpterygoid (transpterygopalatine-fossa ) approach to nasal skull base surgeries. endoscopic nasopharyngectomy for salvage in nasopharyngeal carcinoma, the eustachian tube isthmus is behind the lateral of foramen ovale, and is difficult to dissect the cartilaginous part of Eustachian tube, so we can maximized remove the cartilage of eustachian tube by anatomical landmark of mandibular nerve which pass through the foramen ovale. The internal carotid artery in parapharyngeal space located lateral of the longus capitis, behind the stylopharyngeal fascia and 0.5cm below the posterior of eustachian tube isthmus. The distance between the medial border of internal carotid artery and lateral of opisthognathous of vidian canal is 1cm in vertical plane;②Measurements from cadavers: the distance between columella nasi and the boundary of vidian nerve and anterior genu of internal carotid artery is 84.97±4.27mm, the distance between columella nasi and eustachian tube isthmus is 96.33±2.07mm, the distance between columella nasi and internal carotid artery is 101.56±2.56mm;③Measurements from CT: the mean length of vidian canal is 16.31±2.16mm, the mean length between the sagittal line of opisthognathous of vidian canal and inner margin of carotid canal is 9.98±2.22mm, the shortest distance between eustachian tube isthmus and internal carotid canal is 4.46±0.96mm, the mean distance between opisthognathous of vidian canal and eustachian tube isthmus is 20.08±2.70mm, and the mean distance between opisthognathous of vidian canal and eustachian tube isthmus is 17.74±1.17mmConclusions It is feasible for the endoscopic nasopharyngectomy for salvage in nasopharyngeal carcinoma, and there are important anatomical landmarks for the endoscopic nasopharyngectomy, such as vidian canal, foramen ovale, longus capitis, eustachian tube isthmus and stylopharyngeal fascia. It is difficult to dissect the cartilage of eustachian tube, so we can enlarge the incisal edge in skull base by use vidian canal and foramen ovale as landmarks. vidian canal and foramen rotundum are significant anatomical landmarks in transpterygoid (transpterygopalatine-fossa ) approach in endoscopic skull base surgery... |
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