Anatomical Analysis And Clinical Application Of The Microscopic Extended Transsphenoidal Approach

PartⅠAnatomical researchAnatomical analysis of the exposure of the midline skull base by theextended transsphenoidal approaches and Le fort I osteotomyOBJECTIVE To quantity and compare the surgical exposure of themidline skull base among the extended transsphenoidal approach and Lefort I osteotomy(LFO).METHODS With the assistance of neuro-navigation system, the 3different extended transsphenoidal approaches including the transnasalapproach(TNA) , sublabial approach(SLA)and modified sublabialapproach(MSLA) respectively, and LFO were performed in 12 adult cadavericheads. Under the microscope, the midline skull base structures exposedby the four approaches were observed. With the assistance ofneuro-navigator, the surgical exposure to the anterior skull base,cavernous sinus area and clivus area by four approaches weremeasured .After that, the metered data was analyzed by the statisticssoftware in order to identify whether there were statistics differencesof the surgical exposure provided by the four approaches.Results There was no distinctive difference of the surgical exposureto the anterior skull base provided by TNA and SLA, but wider exposurewas founded using MSLA and LFO, especially the LFO. Considering theexposure of the cavernous sinus and clivus area, there was statisticsdifference among the four approaches, according to the actual data, theexposure area was TNA＜SLA＜MSLA＜LFO respectively. Furthermore, by theMSLA and LFO, the floor of the third ventricle could be opened, and theanterior arch of atlas could be opened by the LFO.CONCLUSION The 3 different extended transsphenoidal approaches andLFO can expose the midline skull base in different degree, which are moredirect and less invasive than the transcranial approach. Because of thedistinction of the surgical exposure, the better choice of the surgical approach should be depended on the localization of the tumor. With regardto the majority of the skull base tumors, MSLA can offer enough surgicalexposure, which was simpler and less invasive than the LFO. However, theclinical effect need to be verified progressively.PartⅡClinical applicationOBJECTIVE To evaluate the clinical application of 3 differentextended transsphenoidal approaches in microsurgery for tumors locatedalong the midline skull base. Meanwhile, the treatment of thecomplications after the extended transsphenoidal approach was discussed.METHODS 21 patients ,form June 2007 to February 2009, with tumorsin the midline skull base, including 11 cases of clivus chordomas, 9 casesof pituitary macroadenomas invading CS and 1 case of tuberculum sellaemeningioma respectively, were surgically treated by microscopic extendedtranssphenoidal approach, with the assistance of neuro-navigationsystem. Among those, 3-D stereoscopic virtual reality images werereconstructed successfully before surgery, which could identify therelationship between the tumors and surrounding structures and conducedto the operations. The data of 3 different approaches, surgical effect,complications and prognosis after surgery was compared, in order tofurther verify the results of anatomical research of partⅠ. Furthermore,the indications of extended transsphenoidal approach and methods to dealwith the complications were be discussed and summarized here.Results Total removal was achieved in 9 cases, subtotal removal in9 cases and most partial removal in another 3 cases, which was confirmedby the images of neuronavigation and iMRI combined with the imaging-scopyafter the operations. In the cases using the transnasal approach andsublabial approach, the resident tumors were found mostly in the cavernoussinus areas and the lower clivus, which could only found in the cavernoussinus areas in the cases by the modified sublabial approach. In 4cases ,the leakage of cerebrospinal fluid occurred, which recoverd completely after the reconstruction of the skull base and correspondingtreatment. Injury of the internal carotid artery did not occur in all thecases.CONCLUSIONS The extended transsphenoidal approach can exposed themidline skull base directly. During the clinical progress, we canmanipulate this approach simplely and conveniently. And the clinicaleffect is satisfactory with modicus complications. However, we also findthat there are differences among the exposed scope afforded by the by thetransnasal approach, sublabial approach and modified sublabial approach,which is coincident with the anatomical conclusions.Le fort I osteotomy can widely expose the midline skull base, fromthe anterior skull base to the cranio-cervico junction, but in theclinical ,the application of LFO is restricted because of thecomplications. In another side, the modified sublabial approach isworthing generalization considered its wide anatomical expose andrelatively simple manipulation.In clinical, the choice of the surgical approaches about the ncludingclivus chordomas, pituitary macroadenomas invading CS and tuberculumsellae meningioma, should base on the following aspects:1,The involved extent of the tumors and the surgical exposuresupplied by the approaches:2,The pathology of the tumors. Because the different kinds oftumors have different growth pattern and prognosis, which hasan influence on the choice of surgical approaches:3,The therapeutic schedules for tumors should be allround,including surgery, chemotherapy and radiotherapy. Theoveremphasize of surgery is not recommended.The complications of extended transsphenoidal approach includeleakage of cerebrospinal fluid and injury of internal carotid artery,which can be well controlled by the suitable methods.