The Anatomy Of Sinus-related Anterior Skull Base Relating To Sinus Endoscopy: Study And Case Report

Purpose:To provide endoscopic sinus surgery with the anatomic reference by studying the anatomy of sinus-related skull base area its adjacent structures.Methods:There are three parts. Part I (anatomy study): Whole,local and endoscopic anotomy were collaborated to study endoscopy-related sinus and skull base structueres. Some data were measured by ruler and some key clinic marks were recognized. The following were included: The anatomy of frontal recess and its adjacent structures; A binding study of the gross and endocsopic anatomy of optic canal; The clinical anatomic study of bony pterygopalatine fossa related with endoscopic surgery; The clinic anatomy of operation on pterygopalatine fossa through nasal cavity under endoscope; Applied anatomy study on the lateral wall of sphenoid sinus and the cavernous sinus under transnasal endoscope. Part II (clinic study): The modification of endoscopic nasal surgery in the treatment of nasopharyngeal angiofibroma; Surgery of Occupation Lesions of the Skull Base Assisted by Sinus Endoscope.Results:1. As the drainage passage of frontal sinus, frontal recess is a complex 3-dimensional structure; The range of frontal recess can be exposed completely by endoscopic frontal sinus surgery with agger nasi approach; The anatomic relationship of agger nasi, uncinate process and ethmoid bulla determine the approach of surgery; The median distance between anterior ethmoid artery, which is the important mark to recognize frontal ostium and skull base, and the joint of columella nasi and alae nasi is 57.3±2.6mm and the median angle with nasal bottom is 51.6±1.6°.2. From the study of gross anatomy, the specific structure of opti canal and internal carotid artery were found.The mean length of the medial wall of optic canal was 9.3±2.3mm. The mean diameter of the optic canal orbital aperture was 4.1±0.6mm. The distances from the midpoint of the medial wall of optic canal orbital aperture to anterior nasal spine was 64.4±4.7mm, and the angle from the midpoint of the medial wall of optic canal orbital aperture to anterior nasal spine was 46.1±5.2°. From the study of endoscopic anatomy, optic canal, looking like a light-reflective band, was alone optic canal orbital aperture posteriorly. Obvious prominence could be found in 7 sides(70%), while not been seen clearly in 3 sides(30%).3. The pterygopalatine fossa showed a long and narrow cleft with seven paths communicating with nasal cavity, mouth cavity, pharynx, orbit, infratemporal fossa and middle cranial fossa. The distances from pterygomaxillary fissures to the beneath midpoints of the zagmatic arch were (33.4±3.1) mm. 70% of sphenopalatine foramen were over and 30% were strided over and no were under the minddle turbinate. With endoscope, the pterygopalatine fossa could be observed as a whole.4. Pathway through nasal cavity can lead to good view of pterygopalatine fossa. The main soft structures in PPF was maxillary artery and maxillary nerve and their branches. The diameter of arteries were smaller than 3 mm.5. From the study of endoscopic anatomy, the specific structure of opti canal and internal carotid artery were found, and the lateral wall of the cavernous sinus could be exposed by tracing the internal carotid artery. The internal carotid artery, oculomotor, trochlear, abducent and optic nerves could be separated completely.6. with preoperative feeding artery embolism, NBCA (N-butyl-2-cyanoacrylate) injection into angiofibroma and suction electricocautery, a seventeen-year-old yang man with nasopharyngeal angiofibroma was treated by endoscopic sinus surgery. After surgery, the operative area was coated with fiber protein glue. No complications had occurred. Intraoperative blood loss was only 150 ml.The angiofibroma was successfully and completely cleared.7. We summarized retrospectively 10 cases of the occupation lesions of the skull base involving the parasinus treated under endoscope. There were 2 cases of nasopharyngeal angiofibroma, 1 case of osteodysplasia fibrosa, 1 case of plasmacytoma,5 cases of inverted papilloma and 1 case of cylindroma. All the lesions were excised entirely indicated by CT and no recurrence after 1-2 years.Conclusion:1. Agger nasi, uncinate process and ethmoid bulla are the important anatomic marks in nasal endoscopic surgery around frontal recess. Accuratelly recognizing the anatomic relationship of frontal recess and its adjacent structures help to improve the effect of surgery and avoid serious complication.2. The binding study of the gross and endocsopic anatomy of optic canal help to recognize optic canal accurately under nasal endoscope, which can improve the veracity of transnasal endoscopic optic nerve decompression. The optic canal are always appeared to be a light band, which can be used to mark of optic canal.3. The data of our study could be regarded as the important anatomical parameters in the operation in endoscopic transnasal surgery in pterygopalatine fossa.4. The endoscopic PPF sugery is safe and practical from the anatomic structres.5. The approach of exposing cavernous sinus visa transsphenoidal by using endoscopic endonasal is simple , minimally invasive , and useful for clinic operation.6. preoperative feeding artery embolism, NBCA injection and suction electricocautery make the endoscopic sinus surgery little blood loss. It also make the patient little anguish. PVA embolism is a better choice than gel in nasopharyngeal angiofibroma.7. For the occupation disease of the skull base involving sinus, we can take advantage of the nasal endoscope.