| BackgroundClivus and ventral region of foramen magnum locates in the middle part of skull basis,where meningioma,hemangioma,chordoma,lymphoma and cholesteatoma often occur.Deeply located,and having close relationship with important structures such as pituitary,brainstem,Ⅲ～Ⅷof the cranial nerve,basilar artery,glomus jugulare and cavernous.Especially,holding the lower part of medulla oblongata and pontine in addition to the surrounding structural barriers of osteoarthritis,it is very difficult for the conventional surgery to reach this area and causing great difficulty in surgical treatment in this region.Although there are relatively many types of clivus region surgery,including various entry routes,through infratemporal,suboccipitals extreme lateral,passingâ… -pharyngeal and nasal tip,now a general entry route has not been found yet to apply to all the cases.These different surgical entry routes have directly relationship with the special anatomical structure of clivus region.Knowing its patterns and adjacent relationships between clivus region and its surroundings,it is helpful to find the best entry route.Researches on different entry routes of clivus region surgery have become the hot spot of skull base surgery and anatomy of clinical application in recent years.Endoscopy,the symbol of Minimally Invasive Surgery,has been the important progress in now days clinical application.In 1901,Lespinasse used endoscopic in hydrocephalus operation first.In 1978 Bushe had reported the endoscopic surgery in saddle area.Jankowski had conducted endoscopic surgery to cure tumor in saddle area.Later Jho and Cappabianca had also conducted endoscopic surgery of trans nasal approach and proved the feasibility and good surgical result.Due to the complex anatomical structure of skull base,the procedure has certain constraints in clinical application and can only be applied in surgical treatments such as: cerebrospinal fluid and rhinorrhea repair surgery,optic canal decompression,pituitary adenoma and violations of intracranial mucocele of the paranasal sinuses.With the continuous development of the micro-endoscopic equipment and technology,the surgical treatment techniques through neb-skull base can be widely used and has become the first chosen treatment for pituitary adenoma in clinical application. Thanks to the continuous accumulation of surgery experiences,and more comprehensive researches on endoscopic anatomical structure of skull base,except in the sellar region,the surgery entry routes has been continuously expanded,and has gradually been applied to surgical treament in various skull base lesion regions such as pterygopalatine fossa,orbital apex,cavernous,petrous apex,clivus and craniocervical junction.In 1987,Weiss had first named and described the expanded entry route through Sphenoid.With the continuous improvement in the surgical regions,gradually expanding to the regions of anterior cranial fossa,saddle area, cavernous,clivus,and craniocervical junction.The extended endoscopic endonasal approach,in vertical direction,can be exposed from bottom saddle area to foramen magnum,in horizontal direction,can be exposed to bilateral temporomandibular joint, from sides can be exposed to internal carotid artery,foramen ovale,foramen rotundum,petrous apex petrous apex and jugular vein ball.Extended endonasal approach has unique advantage:simple,direct,quickly reaching the surgical region. With comprehensive development of endoscopic technology,many scholars have tried surgical indications to continuously extend the endoscopic endonasal approach in clivus region.This research is based on the research of applied anatomy of the deeply located clivus region structure for endonasal approach which has close important structural relationships with pontine,the ventral medulla oblongata, internal carotid artery,basilar artery,glomus jugulare and cavernous.This research aims to study the endoscopic anatomy of surgical entry routes,observe exposure region,determine anatomy indication,and provide more detailed information of anatomical,comparative anatomy,endoscopic anatomy and anatomical measurements for clinical application in lesion clivus region with surgical treatment of extended endoscopic endonasal approach.Objectives1.Establish surgical landmarks for the surgery through neb-ventral craniocervical junction under endoscopic,provide anatomical basis.To conduct the micro-anatomical descriptions and endoscopic description on the surgery via endonasal approach to clivus and ventral foramen magnum and its surrounding structures and provide substantial morphological evidence and basic anatomy for clinical doctors to conduct the extended endoscopic endonasal approach to clivus and ventral foramen magnum surgery under the endoscopic.2.In the same surgical region to find the comparative relations among endoscopic anatomy,sectional anatomy and imaging anatomy and provide clinical doctors with detailed images and data information.3.This research has conducted measurement of relevant data on low-middle part bone structure of clivus.With these data measurement,it is importantly meaningful not only to identify surgery safety scope to avoid accidental injury of important structure but also very helpful to the selection of suitable endoscopic equipment and provide a quick and easy entry route for clinical doctors to conduct the surgery in clivus region.4.To accumulate experiences in developing virtual software for the extended endoscopic endonasal approach surgery on region of clivus and craniocervical junction.Materials and methods 1.20 Dry skull specimens,conduct measurement of the anatomical landmark points on the surroundings of the clivus of osseous skull base;20 formalin-fixed complete head and neck specimens,to fill red color emulsion in artery,to complete simulate surgical endoscopic endonasal approach,conduct anatomical observation on anatomical characteristics of surgical entry route that passes nasal to clivus and ventral foramen magnum and establish surgical landmarks.And utilize vernier caliper (precision 0.02mm) and compasses to gauge the important anatomical structures related to the surgical entry road in this region.â‘ Pterygoid canal,pharyngeal opening of eustachian tube,the breakdown hole,outside ostium of hypoglossal nerve,internal carotid artery,atlantoaxial vertebral artery,atlanto-axial internal carotid artery,the distance from front edge of the medial occipital condyle to midline.â‘¡Anterior nasal spine away from the pharyngeal tubercle,front edge midpoint of foramen magnum, distance of anterior tubercle of atlas.Study from national references on the forms different structures of osseous skull base clivus region,conduct comparison on measurements and adjacent relations and sectional anatomy,SPSS13.0 software statistical analysis research.2.Five fresh complete head and neck specimens,fill in red color emulsion. Utilize 4mm diameter,18cm length,0°and 30°nasal endoscopic and part of endoscopic equipments,completely simulate endoscopic endonasal approach.Prove identified surgical landmarks;understand anatomy of endoscopic surgical region to provide anatomical evidence for further development of clinical operation.3.The same fresh body head specimens,surgical passage 64-row CT bone structure,three-dimensional reconstruction,vascular three-dimensional reconstruction after filling PbO in artery and comparison study of imaging information after 1.5tMRI scanning.4.Randomly choose 20 healthy people's scan information from 64-row spiral skull CT;conduct CT measurement of the important anatomy structures of skull base and surgical passage related important bone vascular three-dimensional reconstruction,and conduct comparative study on the measurement results with that of the fix specimens. 5.Clinical research:expand the clinical operation and applied anatomy research on endoscopic endonasal approach to clivus and ventral foramen magnum.Results and Discussion1.Mesurment of osseous clivusOsseous clivus is formed by occipital base and sphenoid body,about 45°leaning forward.Slop upper border is sellar region back,lower border is front edge of foramen magnum,the both sides border by foramen lacerum,rock pillow crack, jugular foramen,inside mouth of hypoglossal canal and other structures.The distance between the front edge of foramen magnum to the back of sellar region is (45.51±2.60)mm.The thickness of anterior margin of foramen magnum is(3.45±0.69)mm.Hypoglossal nerve root through pass sidewall of foramen magnum of hypoglossal canal;inner ears door locates at the inside sidewall of 1/3 front of rock cone;the distance from front edge of inner ears doors to the exterior edge of tuberculum sellae is(25.55±3.07)mm;the vertical distance between the sellar back and the line connecting the bottom walls of the both sides inner ears doors is (20.1±1.8)mm;the thickness of inner ears upper bone wall is(7.19±1.23) mm.2.The surgical landmark points for endoscopic pass nasal to craniocervical junction include:Middle turbinate,choanal,Pharyngeal opening of eustachian tube, nasopharyngeal mucosa opening,nasopharynx mucosa,longus capitis and longus colli,front edge of midpoint of foramen magnum,anterior tubercle of atlas.The endoscopic endonasal approach completely expose the craniocervical junction region, its shortest distance is(89.75±2.80)mm,the range of lower clivus toward both sides of stripping bone window is(10.75±0.63)mm;Differences have not been not found in other left and rights landmarks indication.3.Observation on skull base clivus region relevant Anatomical structure3.1 The Petrous bone section of internal carotid arteryDivided by the knee part,the carotid artery is identified as vertical section and horizontal section.Internal carotid artery ascends vertically from the outside mouth of carotid artery,then bend and turn forward inside appearing vertical to the foramen lacerum,bend and turn upward to cranial,then comes to the cavernous section. Internal carotid artery petrous bone section,except the entry point of carotid artery where the dense fibrous tissues attach to fix under the petrous bone,is easy to separate from the connective tissue of carotid artery.3.2 Dorello tube and its contentsDorello tube locates at the upper clivus exterior side irregular-shaped fibrous pipe,mainly passed by abducens nerve and the petrosal sinus.Abducens nerve locates at the entrance of Posterior fossa subdural,(12.24±3.5)mm under the rear-clinoid, distance between both sides is(19.71±1.79)mm.Abducens nerve inside clivus subdural behind the skull,almost vertically upward(5.07±1.43)mm to the Dorrello tube entrance,then becomes flat passing Dorello tube outside 1/3 or middle 1/3.From petrosal sinus to rear part of Cavernous,parallels with abducens nerve and pass through Dorello tube,from petrooccipital fissure to Jugular foramen and inject into jugular vein.3.3 The form of the jugular foramen and the adjacentJugular foramen is the extended area of the rear petrooccipital fissure,locates at the lower part of clivus lateral,forms and sizes are changeable,jugular foramen uses the jugular vein tip of temporal bone and occipital bone to separate jugular foramen, and jugular foramen is single hole,which means incompletely separated into rear exterior section(intravenous section)and front interior section(nerve section),in this form,left and right side respectively has 86%and 80%.Separated by osteopontin, jugular foramen is double-holed,in this form,left side and right side respectively has 4%and 20%percent.The areas of left and right side Jugular foramen respectively are (4.6±2.8)mm~2 and(6.2±3.0)mm~2.The possibility is 60%that right side area is larger than left side area,18%that left side area larger than right side area,22%that the two sides' area is the same.Glossopharyngeal nerve locates at the rear medial part inside the dural sheath within Concave triangle,position constantly fixed.Vagus nerve and accessory nerve locate inside the same Dural sheath,vagus nerve at front accessory nerve at rear,these two nerves' locations have 3 situations:â‘ locates at anteromedial part,has 93%;â‘¡Inside the Fibrous septum between the two parts,has 6.5%;â‘¢ Locates at the medial of rear lateral part,has 0.5%.Jugular vein locates at rear lateral section,position constantly fixed.The distance between two jugular foramen is 45.3mm.Glossopharyngeal nerve,vagus nerve,accessory nerve locate at the anteromedial part of Jugular foramen,also the nerve section,and jugular vein locates at the posterolateral section,also the vascular section.The medial of the hole is jugular tubercle,(1.5±0.43)mm from the Jugular foramen nerve section.3.4 Relations among clivus and Pontine and Ventral medulla oblongataOn the sagittal section,clivus faces pontine and ventral medulla oblongata, pastes most tightly with the pontine base and 1/2 on medulla oblongata.Basilar artery is at the 1/3 section of basilar pontine sulcus with rostral pontine sulcus,which is formed by convergence of vertebral artery,respectively occupies 33.3%and 66.7%. From upper edge of basilar sulcus,close to the interpeduncular fossa is posterior cerebral artery,whole length(28.5±1.2)mm,occupies 3/4 of the entire clivus.The length of 1/3 section of lower,middle and upper basilar artery respectively is 5.3mm, 4.6mm and 4.3mm.Intravenous vein at the front middle of pontine and medulla oblongata winds along the midline,exterior diameter 0.3mm;0.5cm from its lacteral runs the parral anterolateral vein,exterior diameter about 0.3mm;between the above mentioned Intravenous veins,there are 3 to 5 horizontal running veins intersecting,its exterior diameter is about 0.3mm.The middle part of pontine arm and pontine medullary sulcus rightly faces the border of the 1/3 middle section and 1/3 middle lower section of clivus.Olivopontocerebellar locates at the anterolateral part of medulla oblongata,under the rostral pontine sulcus,3-4mm above it is the facial nerve,vestibular cochlear nerve root,at its rear part locates the glossopharyngeal nerve,vagus nerve and accessory nerve root.Its front part is hypoglossal nerve root.3.5 The adjacent of foramen lacerumForamen lacerum locates at the lacteral of upper clivus,the irregular hole crack between the petrous apex,occipital base and posterolateral part of sphenoid body, about 1cm in diameter,the lower half of the hole is sealed by fibrocartilage,and only tiny Blood vessels and nerves pass through it.Internal carotid artery passes upward its upper half,turn inward to intracalvarium.The hole's front boundary line is sphenoid body,the root of pterygoid process and ala magna ossis sphenoidalis, posterior and lateral borders by the tip of petrous bone section,medial is the occipital base.The distance between the inside edges of the two foramen lacerum is (18.0±1.9)mm.4.20CT measurement results of healthy examined peopleUnder endonasal approach,completely exposing middle and lower parts of clivus,the shortest distance is(89.75±2.80)mm;The ranges of stripping the inferior wall of sphenoid sinus and the lower clivus were bounded by pterygoid canal and foramen lacerum,and the CT measured distances from the median line were(9.37±0.59)mm and(10.75±0.63) mm respectively.The Skull base and blood vessel three-dimensional reconstruction results:thin layer head and neck CT scan can clearly display,besides tissue such as midbrain,pontine,medulla oblongata,spinal cord,important skull base bone structures,which includes petrous bone,clivus, mastoid,interior auditory,rear and front arch of atlas,articular surface of atlas, pharyngeal tubercle,basion,foramen lacerum,hypoglossal canal,internal carotid artery,etc.Applying the measurement software can accurately measure the distance of relevant structures,which includes the distance from interior auditory,rear and front arch of atlas,pharyngeal tubercle,front edge of foramen magnum,foramen lacerum,hypoglossal canal,Internal carotid artery canal to the midline.The applied software can observe the shape of osteoarthritis of meatus.The size of interior auditory,the size of Foramen magnum,the shape of clivus,etc.Sometime,it can also display the relations of Cranial nerves.Head neck three-dimensional reconstruction of spiral CT can more directly display the anatomical structure of the nasus osseus passage,sellar region,clivus,rear and front arch of atlas,which includes clivus region(size,form),foramen magnum(size,form),foramen lacerum,jugular tubercle, inner ear door,jugular foramen,hypoglossal canal,condylus occipitalis,external occipital protuberance,etc.This group all has relatively well displayed the structure mentioned above.The three-dimensional image reconstruction by method VR or SSD of clivus and ventral foramen magnum can simulate the approximate anatomy of the region of endonasal approach surgical position and provide valuable reference for surgical comparison.5.Clinical research demonstrates the following anatomical structures relating the success and failure of the surgery before endonasal approach.5.1 Nasal septumNasal septum is mainly constructed by septal cartilage and perpendicular plate of ethmoid bone,forming the most front region of pass nasal surgical passage.5.2 Sphenoid sinusSphenoid sinus is a aerated space within corpus ossis sphenoidalis.Its forms and sizes can vary largely.The opening of sphenoid sinus is the anatomical landmark to determine the sphenoid midline,all locates inside the sphenoethmoidal recess ethmoid fossa of the rear turbinate on nasal cavity,which is the landmark to define the bottom of sellar region.Its ostium shapes can vary in oval,round or slit-shaped. The average distance from nasal columella root to the low end of sphenoid sinus ostium and the bottom of sphenoid sinus is 60mm and 14mm respectively.These anatomical data is helpful to identify the location of sphenoid sinus.After cracking open the anterior wall of sphenoid sinus,the sellar region is exposed.In side the sphenoid sinus,there can be septal,its horizontal diameter averages at 22mm,rear and front to rear diameter 22mm,vertical diameter 20mm.The lateral wall of sphenoid sinus has close relations with optic nerve and internal carotid artery,the eminence of optic nerve canal locates at upper part of lateral wall of sphenoid sinus, and the eminence of internal carotid artery locates at the bottom of saddle area of the lateral wall of sphenoid sinus.5.3 Optic nerveThe interior walls of most optic nerves closely border with sphenoid sinus.Optic nerve canal tips enter the sphenoid chamber to form protuberans,16.2%of the above mentioned protuberans is larger than 1/4 of its canal diameter.Since sphenoid sinus change very often,ethmoid also often invades the upper part of sphenoid sinus from behind,the ajacent relations of interior wall of optic nerve canal is relatively complex. Sometime since the sphenoid sinus septal is bent,the optic nerve canal from both sides is bordered with one side of the sphenoid sinus.The adjacent relation of The Lateral wall of sphenoid sinus and optic nerve canal is determined by the the extent of gasification of the rear ethmoid chamber.The entire or the most part of optic nerve canal locate at the lateral wall of sphenoid sinus.5.4 Internal carotid arteryThe Internal carotid artery protuberans can be divided as rear saddle area,low saddle area and front saddle area.The Internal carotid artery enters intracalvarium at the petrous apex of internal carotid canal,through foramen lacerum to enter cavernous sinus,it extends forward inside the cavernous sinus,and at anterior clinoid process it levels up pass through out of the top of the cavernous sinus,it then turns to the medial of the anterior clinoid process and goes upwards.The above-mentioned route closely attach at the lateral wall of sphenoid sinus,and form a pressure track convex to the inside sphenoid sinus.Some part of the internal carotid artery form protuberans inside the sphenoid sinus.Due to the variation of the extent of the gasification,the possibility rates to form the protuberans vary.The same situation happens.Since the sphenoid sinus septum is relatively bent,sometimes it can happen that one side of the sphenoid sinus is bordered by both sides of the internal carotid artery.The thickness of the bone wall of the pressure track of the internal carotid artery inside the sphenoid sinus is about 1.0mm,sometimes it defects naturally.5.5 Sphenopalatine artery and its branchesSphenopalatine artery is the end branches of maxillary artery.It runs up and inward from pterygopalatine fossa,and enters the Nasal cavity at sphenopalatine foramen which locates at slightly upper part of the rear end of middle turbinate.The distance from sphenopalatine foramen to nasal columella root and the lower edge of Sphenoid sinus ostium is about 62mm and 13 mm respectively.The Sphenopalatine artery brances inside the nasal cavity mainly are lateral nasal cavity artery and arteria nasalis posterior septi.The Lateral nasal cavity artery often divides as Upper,middle and lower section of Turbinate artery,respectively entering the corresponding turbinate from the rear end of different turbinate.The arteria nasalis posterior septi is often divided as upper and lower two branches,which turn into the Nasal septum from the lower part of the Anterior sphenoid sinus ostium.The branch close to the sphenoid sinus ostium is called the upper branch of posterior nasal septum artery,the other one relatively farer from the sphenoid sinus ostium is called the lower branch of arteria nasalis posterior septi.The distance from the upper and lower branches of the arteria nasalis posterior septi to the lower end of the sphenoid sinus ostium is about 3.5mm and 6.5mm respectively;the distance to the wall of sphenoid sinus top is 14mm and 16mm;distance to the wall of sphenoid sinus bottom is 11mm and 7.5mm. The main purpose to understand these data:it is necessary to maximize the Anterior wall of sphenoid sinus when conducting endonasal approach,but not to injure the blood vessel and cause bleeding.5.6 Cavernous sinus and intercavernous sinusesCavernous sinus is the pentahedral structure formed by the folding of the subdural from superior orbital fissure to petrous apex beside the sellar region.The left and right side cavernous sinus is connected by front and rear inter-sinus,lower cavernous inter-sinus can locate among subdural at sellar bottom.At the rear back of the sellar,there can be rear cavernous inter-sinus and back sellar sinus,which intersect with both sides cavernous sinus,upper superior petrosal sinus and inferior petrosal sinus.The cavernous inter-sinus relating to the tumor removal sugery under the extended endonasal approach to clivus mainly is:lower intercavernous sinuses, rear intercavernous sinuses,basilar sinus and back sellar sinus.Conclusion1.To understand the clivus region anatomical structure and its adjacent relations and improve the familiarity level of the whole skull bas clivus region,and indirectly improve the safety level of the related surgery.2.To conduct thorough simulating endoscopic surgery on the same group of fixed body head specimens,collect relevant surgical anatomy data,establish surgical landmarks,measure distances of the important anatomy structures at the skull base, can obtain the surgical safety ranges.3.To conduct endoscopic surgery simulation on the same fresh body head specimen and prime pbo reagent to carry out three-dimensional anatomical reconstruction of CT images and MRI head scan,to obtain more experimental data, which is highly meaningful for clinical guidance.4.The experiment demonstrates that the structures of the ventral craniocervical junction can be sufficiently revealed via endoscopic endonasal approach,completely achieve the operation process of endoscopic simulation.It has great meanings to the intensive trainings for clinical doctors before the surgery.5.Clinical application research via anatomy of minimally invasive approach, further demonstrates which structures are critical anatomical structures to determine whether or not the surgery can be successful,and give direct guidance to clinical doctors to carry out surgery via endoscopic endonasal approach.
|
PDF Full Text Request