Anatomical Research And Clinical Application Of Pituitary Adenoma Invasion Corridor

Part ?: Pituitary adenoma with posterior triangle invasion of cavernous sinus:Anatomical studyObjective: Some Knosp grade 3A-4 pituitary adenomas invade the posterior areas of the CS and show triangular-like structures on axial MRI.Because of their deep location,this area is often blocked by important structures such as the internal carotid artery,which is the most difficult site to reach and the most likely to produce intraoperative residue.In this study,we dissected the surrounding neurovascular structure and defined anatomic boundaries of the posterior triangle of the CS from endonasal and transcranial perspectives,respectively.Methods: Eight embalmed adult cadaveric specimens were prepared for this study.Three injected specimens were used for transcranial microsurgical dissection.Five specimens were used for endoscopic endonasal dissection.Results: According to our endoscopic and microsurgical anatomy,this area is a square-based pyramid structure,and its four surfaces are expressed as follows: medial surface: the three sides of the triangle are formed by the posterior petroclinoidal ligament,the petrosphenoidal ligament,and the connection of the petrosphenoidal ligament attachment and the posterior clinoid process;lateral surface: the triangle is formed by the anterior petroclinoidal ligament and CN V1,and the two are connected at the entrance of the oculomotor nerve(the trochlear nerve runs within this triangle);upper surface: this triangle is similar to the posterior portion of the oculomotor triangle;and bottom surface: the petrosphenoidal ligament and CN V1 run along the lateral wall of the CS,and the two are connected within the CS to form a triangle(this triangle is equivalent to the plane of the abductor nerve in the posterior area of the CS.Conclusions: Knowledge of this anatomic structure and key adjacent neurovascular structures is essential for resecting pituitary adenomas with CS invasion.Therefore,we should emphasize that special attention must be paid to this sharp triangular appearance preoperatively shown in axial MRI.Part ?: Pituitary adenoma with posterior triangle invasion of cavernous sinus: surgical approach,and outcomesObjective: From the perspective of endoscopic endonasal surgery,two surgical approaches into the posterior triangle of the CS are associated with the ICA: medial and lateral.In this study,we propose the “two points and one line” method to predict the surgical approach of PA with posterior triangle invasion of the CS based on the preoperative axial MRI scan.Then we analyzed the clinical significance of this method.Methods: We retrospectively analyzed the medical records and surgery videos of 372 cases of PA patients from January 2017 to December 2019 in our center.Then we screened out the cases with posterior triangle invasion of CS and analyzed their surgical outcomes and the accuracy of “two points and one line” method.Results: A total of 37 posterior areas of the CS were involved in 35 patients.The accuracy of the "two points and one line" method in predicting the surgical approach is 86.5%(32/37).All 3 patients with Knosp 3A underwent gross total resection(GTR).Twenty(62.5%)patients with Knosp 4 underwent GTR,9(28.1%)patients underwent subtotal resection,and 3(9.4%)patients underwent partial resection.Preoperative symptoms were alleviated to varying degrees,and no worsening occurred.Postoperative complications included 2(5.7%)cases of cerebrospinal fluid leakage,1(2.9%)case of meningitis,2(5.7%)cases of permanent diabetes insipidus,and 3(8.6%)cases of transient cranial nerve palsy.Conclusions: PA with posterior triangle invasion of CS can be totally resected through endoscopic endonasal surgery with low complications and mortality rate.As a preoperative predictive method of surgery approach,“two points and one line” method can effectively predict the approach of PA with posterior triangle invasion of CS.Part ?: Pituitary adenoma with posterior triangle of cavernous sinus-oculomotor cistern invasion: Membranous anatomy and clinical application.Objective: Posterior triangle of cavernous sinus-oculomotor cistern extension as an invasion mode of pituitary macroadenoma through oculomotor trigone proposed recently,was one of the main reasons multilobed tumor comes into being.It?s important to understand the membranous anatomy around oculomotor cistern so as to achieve total resection of such kind of PA.In our study,we analyzed the membranous anatomy around oculomotor cistern through epoxy sheet plastination and discussed its clinical significance.Methods: We perform epoxy sheet plastination on 9 cadaver head specimens(18 sides totally)following the order: tissue mass preparation,dehydration and degreasing,vacuum impregnation,solidification and tissue section.Meanwhile,we analyzed the surgery outcome of PA with oculomotor cistern extension in our center.Results: The membranous structure of oculomotor cistern is divided into two layers.The inner layer extends from the arachnoid layer of the posterior cranial fossa.The outer layer is formed by the subsiding part of dura mater from superior wall of CS.The two-layer membranous structure is closely attached at the front and looser at the rear.From the sagittal plastination section,the dura mater anterior to oculomotor nerve is closely attached to nerve outlet at the superior wall of CS but larger gap exists between the posterior dura mater and nerve.26 cases of PA with oculomotor cistern extension in total were included into study.22 cases achieved total resection of tumor.18 cases were found with preoperative oculomotor nerve palsy and relevant symptoms while 12 cases were relived postoperatively and 6 cases remained.Conclusions: The oculomotor cistern invasion by tumor is tented to be further extended from the posterior side of nerve.The thickness of two dura mater and size of oculomotor cistern jointly leads to this special invasion mode.Early-stage total resection of tumor inside the oculomotor cistern can effectively improve the oculomotor nerve palsy and prevent the tumor from further spreading to parapeduncular space.Part ?: Invasive Corridor of Clivus Extension in Pituitary Adenoma: Bony Anatomic Consideration,Surgical Outcome and Technical NuanceObjective: It is well known that the clivus is composed of abundant cancellous bone and is often invaded by pituitary adenoma(PA),but the range of these cancellous bone corridors is unknown.In addition,we found that PA with clivus invasion sometimes accompanied by petrous apex invasion,so we speculated that the petrous apex tumor originated from the clivus cancellous bone corridor.The aim of this study was to test this hypothesis by investigating the bony anatomy associated with PA with clival invasion and its clinical significance.Methods: Twenty-two cadaveric heads were used in the anatomical study to research the bony architecture of the clivus and petrous apex,including six injected specimens for microsurgical dissection and sixteen cadavers for epoxy sheet plastination.The surgical videos and outcomes of PA with clival invasion in our single center were also retrospectively reviewed.Results: The hypoglossal canal and internal acoustic meatus are composed of bone canals surrounded by cortical bone.The cancellous corridor within clivus starts from the sellar or sphenoid sinus floor and extends downward,bypassing the hypoglossal canal and finally reaching the occipital condyle and the medial edge of the jugular foramen.Interestingly,we found that the cancellous bone of the clivus was connected with that of the petrous apex through petroclival fissure extending to the medial margin of the internal acoustic meatus instead of a separating cortical bone between them as it should be.It is satisfactory that the anatomical outcomes of the cancellous corridor and the path of PA with clival invasion observed intraoperatively are completely consistent.In the retrospective cohort of 49 PA patients,the clival component was completely resected in 44(89.8%),and only 5(10.2%)patients in the early-stage had partial residual cases in the inferior clivus.Conclusions: The petrous apex invasion of PA is caused by the tumor invading the clivus and crossing the petroclival fissure along the cancellous bone corridor.PA invade the clivus along the cancellous bone corridor and can also cross the hypoglossal canal to the occipital condyle.This clival invasion pattern presented here deepens our understanding of the invasive characteristics of PA.