| Research backgroundCavernous sinus is an important pair of dural sinus.It is located in the middle cranial fossa and both sides of the sella turcica,which contains oculomotor nerve,trochlear nerve,,abducens nerve and internal carotid artery,sympathetic nerve plexus and venous space go throught cavernous sinus.It is always invaded by invasive pituitary adenoma, chordoma,meningeoma,,nasopharyngeal malignant tumor and other skull baselesions. Although the depth and the narrow space of cavernous sinus,it is very complex and closely connected and related with many important structures of the skull base region.Cavernous sinus had been the focus in the anatomy and skull base surgery research,but it had also been seen as a restricted area of surgical operation.Until 1965, Parkinson[1] opearated into the cavernous sinus region through the lateral wall of it and successed in the treatment of internal carotid cavernous sinus fistula.Research on the microsurgical anatomy and surgical techniques involving the cavernous sinus region began to develop and improve gradually from then on. At present,cavernous sinus region is no longer "non-touch".Research on the morphology and adjacent relationship of the anatomic structure in cavernous sinus region and its surrounding can provide a safe guarantee for the mode and approach of the endoscopic operation.The exposure of both sides in the bone window range in the traditional endonasal transsphenoidal approach to cavernous sinus region arrives mainly to the bony eminence which was made by internal carotid artery in the sphenoid sinus cavity.There were some limitations in the traditional endonasal transsphenoidal approach to cavernous sinus region, which were shown in the following aspects:1.the range of the sphenoid ostium was small,as well as the operative field,so the space of operation was insufficient,and there were some interference between the surgical instruments;2.because of the narrow space of the operation,for those which were invaded by the tumor in the parasellar cavernous sinus,the bottom of temporal lobe and the sphenoid platform,it was unable to judge the relationship of tumor,intracavernous internal carotid artery,abducent nerve and the cranial nerve which were located on the lateral wall of cavernous sinus.Thus,it could not judge the degree of resection and residual of the tumor,as well as the position. Since 1987,Weiss first proposed and described in detail about the "expanded transsphenoidal"surgical operation,the surgical approach has been gradually developed and applied. Application by extended endoscopic endonasal transsphenoidal approach to cavernous sinus has become a focus in the cavernous anatomical region,many experts and scholars have continued to explore and improve in the surgical approach and the method of operation.At present,the approach of extended endoscopic endonasal transsphenoidal is based on the traditional approach,and further expanded from both sides of the bone belonged to sphenoid sinus cavity to the outer wall of the cavernous sinus region.This approach has become the first choice for the treatment of cavernous sinus lesions.Imaging examination should be performed before the extended endoscopic endonasal transsphenoidal approach to handle the cavernous sinus region lesions,in order to further determine the location.shape and other characteristics of the lesions,and provide imaging data for the approach and correct design of the surgical operations.With the development of modern imaging technology,the detection rate of cavernous sinus disease is increasing.Radiographic images not only can clearly show the morphology of cavernous sinus region,but also display the distribution of cranial nerve.lt plays an important role in diagnosing the invasive degree of the lesions in cavernous sinus and its surrounding,as well as whether or not invaded.Therefore,by detailed analysising the image manifestations of the important anatomical structure in cavernous sinus region with CT plain scan and enhancement,MRI plain scan,routine enhancement and dynamic enhancement,the structure,shape and content of the region can be further identified,these can provide imaging evidence for endoscopic operation and achieve the goal of reducing the risk of operation and the postoperative complications.Objective:In this paper,research about the detailed anatomy of cavernous sinus regions on cadaver heads by extended endoscopic endonasal transsphenoidal approach can provide the anatomical reference to handle the cavernous sinus region lesions.At the same time,combining with CT,MRI and other image data of cavernous sinus region can further clarify important anatomical marks for the surgical approach,and explore safety range of the operation,so as to reduce surgical risk and postoperative complications of the cavernous sinus.Specifically,this research mainly consists of the following two parts.The first part mainly uses dry adult’s cadaveric heads as the research object,and completes the extended endoscopic endonasal transsphenoidal approach on them.By measuring,analysising and statisticsing the meaningful signs of the anatomy,the specific contents include the size and position of sphenoid ostium,the type of the gasification for sphenoid sinus,the observation and positioning significance of the main anatomical marks for sphenoid sinus cavity,the morphology of cavernous sinus and its surrounding,the shape and distribution of intracavernous carotid artery and cranial nerve ect.The second part mainly selects adult’s CT and MRI images of cavernous sinus region without lesions, and detailed analysises the characteristics of important anatomical structures of cavernous sinus region throught CT plain scan, enhancement,MRI plain scan,routine enhancement,and dynamic enhancement.The interval distance of the intracavernous internal carotid artery and other important structures are measured and analyzed,those can provide imaging reference basis for the extended endoscopic endonasal transsphenoidal approach to cavernous sinus region.Methods:7 cases (14 sides) of adult’s dry cadaver heads were treated with 10% formalin fixed, and all the specimens were exposed and observed under 0° endoscopy.Endoscopic transnasal approach exposed sphenoid sinus,measured the distance from anterior nasal spine to sphenoid ostium, resected the lower end of the superior turbinate,exposed sphenoethmoidal recess to make sure the sphenoid ostium.Used an electric grinder to expand the sphenoid ostium and grind the bone of the anterior wall and lateral wall belonged to sphenoidal sinus,observed the type of sphenoid sinus gasification,the distribution of the septa and the adjacent relationship of sphenoid sinus and sphenoid bone.Grinded all of the sphenoid sinus septa,stripped the mucosa of the sinus cavity,then endoscopic could display clearly the bone landmarks of sphenoid sinus.The bottom of the sellar was located in the central region of the sinus cavity, the backward was slope sag,the both sides were Optic protuberance,Carotid protuberance,Opticocarotid recess. Grinded off the bone which was in front of cavernous sinus,and exposed clearly the structures of the anterior wall,medial wall and lateral wall.Opened cavernous sinus,exposed the anatomical structures of internal carotid artery,oculomotor nerve,trochlear nerve,trigeminal nerve and its branches,as well as the abducens nerve.Grinded off the sphenoid platform, exposed the anatomic structures of optic nerve,optic chiasma and pituitary stalk.At the same time,the image data were collected,and the important structures were measured and recorded.Randomly selected 25 cases adult’s CT and MRI images of cavernous sinus region without lesions of Guangdong General Hospital,by detailed analysising CT plain scan,enhancement, MRI plain scan,routine enhancement and dynamic enhancement about cavernous sinus region important anatomical structures,the interval distance of intracavernous internal carotid artery and other important structures were measured.Used SPSS 19.0 software to carry out the experimental data for statistical analysis.Measurement data was expressed by x±s,used t for test,and determined P<0.05 for a statistically significant.Results:1.Sphenoid ostium was presented as "eight-shaped" symmetrical distribution, which was located in the sphenoethmoidal recess of the posterior of the middle nasal passage.The length from anterior nasal spine to sphenoid ostium is 66.86±3.47mm (left),66.37±3.62mm (right).respectively.2.The types of sphenoid sinus were mainly saddle or saddle pillow. In 7 cases,1 cases was conchiform,2 cases were saddle pillow types and 4 cases were saddle types. The number,shape, location,direction of sphenoid sinus interval had obvious variation,and they were not completely similar.3.The number of the position about intracavernous internal carotid artery had three distribution types,2 cases were lateral convex types,8 cases were center types,4 cases were medial types;The number of the shape could also be divided into three types,2 cases were straight line types,7 cases were middle curved types,5 cases were expressed as "S"types.4.57.1%(8 sides) of intracavernous internal carotid artery were closely next to the pituitary lateral wall,while there was 42.9%(6 sides) which had a gap with the pituitary lateral wall.5.Intracavernous internal carotid artery was divided into five segments from the bottom to the top,posterior vertical segment (also known as broken hole segment), post bending segment, horizontal segment, forward bend segment and anterior vertical segment (also known as clinoid segment),respectively.6.The main branch vessels of the intracavernous internal carotid artery was the inferior cavernous sinus artery,meningohypohyseal trunk and hypophyseal capsular artery (McConell capsular artery).The lateral wall of cavernous sinus distributed oculomotor nerve,trochlear nerve, abducens nerve and the first branch of trigeminal nerve from top to bottom, respectively.7.The imaging examination of cavernous sinus region with MRI coronal plain scan and dynamic enhancement was the best. But if suspecting skull base and orbital apex bone were destructed, CT was still needed to examinate.CT examination was best for observing the changes of the skull base bone, the destruction of the orbital apex and the calcification in the lesions.Conclusion:(1) The important anatomic landmarks involved in the extended endoscopic endonasal transsphenoidal approach to cavernous sinus regions:sphenoid ostium,sphenoid sinus anterior ridge,saddle,slope recess,optic protuberance,carotid protuberance,opticocarotid recess,intracavernous internal carotid artery,oculomotor nerve,trochlear nerve,abducent nerve,the branches of trigeminal nerve etc.(2) The position of sphenoid ostium (sphenoethmoidal recess) was relatively constant,and it could be used as an anatomical landmark.In the clinical operation,sphenoid ostium was important in finding and entering the sinus cavity.The enlargement of the sphenoid ostium anterior could directly affect the exposure of the operation field.The gasification configuration of sphenoid sinus in our country was well, mainly for the saddle or saddle pillow types, and it could be used for extended endoscopic endonasal transsphenoidal approach.(3) Sphenoid sinus was an important anatomical structure from the nasal cavity to cavernous sinus.The scope of cavernous sinus region could be roughly located according to the most constant anatomy landmarks,such as opticocarotid recess, saddle bottom and slope in the sphenoid sinus.(4) Oculomotor nerve,trochlear nerve,abducent nerve, trigeminal nerve and intracavernous internal carotid artery were the most important anatomical structures in cavernous sinus region and their forms were more variable.Knowing the position and the distributing of vessel and cranial nerve in this area had important guiding significance for clinical operation.(5) Fine sectional image examination and detailed imaging analysis could help to make the correct diagnosis of the structures and lesions in cavernous sinus region.For the diagnosis and surgical operation,it was particularly important to select appropriate image examination according to the characteristics of the lesions.(6) Familiared with the anatomy of cavernous sinus region, interpretated in detail preoperative CT and MRI image data of patients,could obtain more information about the anatomy of the lesions when they were integrated.By this way we could improve the safety and efficacy of surgery. |
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