Study And Compare The Anatomy Of Neuroendoscope-assisted Keyhole Approach To Sellar Area

Objective:Study and compare the anatomic features of the sellar area in the three neuroendoscope-assisted keyhole approaches: supraorbital keyhole approach, pterional keyhole approach and transcallosal-septum pellucidum- interforniceal keyhole approach, and quantify the operative exposure obtained by those surgical approaches. The purpose was to supply the anatomic basis and surgical approaches for clinical application under neuroendoscope assisted microscope of sellar area.Methods: Five cadaveric adult heads that fixed with formalin soaked in alcohol, dissect the neck blood vessel, intubation and washing, perfused with colour latex. Then the supraorbital keyhole approach, the pterional keyhole approach and the transcallosal-septum pellucidum-interforniceal keyhole approach were performed on the cadaveric heads. For each surgical approach, the structures of sellar area were observed under microscope that assisted by neuroendoscope, compare the size of each incision and the bone piece,the value of four operating interspaces. Remove part of the cranial bone and brain tissue, measure the distance to the difined anatomic points, the exposed area was calculated by the Heron'sformula, analysis of variance followed by SPSS 14.0 which was used to determine significant differences among the exposed area.Result:(1)Data result: the exposed areas are 279.33±13.63㎜~2,290.55±14.55㎜~2,86.47±5.33㎜~2 for the supraorbital keyhole approach, pterional keyhole approach and transcallosal-septum pellucidum- interforniceal keyhole approach. Pterional keyhole approach had a significantly larger exposed area than supraorbital keyhole approach (P<0.05). Supraorbital keyhole approach had a significantly larger exposed area than transcallosal-septum pellucid- um-interforniceal keyhole approach (P<0.05). Pterional keyhole approach had a significantly larger exposed area than the transcallosal-septum pellucid- um-interforniceal keyhole approach (P<0.05).(2)Neuroendoscope can be used to observe the whole hidden anatomic structures via the constrictive interspace but not need to drag the important structures, also can eliminate the dead zone under the microscope and observe the impalpable structures especially slim artey clearly. (3) By both the supraorbital keyhole approach and pterional keyhole approach under neuroendoscope or/and microscope can expose the structures of the interspaces in the saddle region in varying degrees, include anterior clinoid process, optic nerve, optic chiasma, diaphragma sellae, pituitary stalk, oculomotor nerve, Willis circle and minute perforator artery, dorsum sellae, posterior clinoid process, etc, especially the ventral brain stem and basilar artery and its barnehes. Anterior cerebral artery A1, anterior communicating artery, optic chiasma and optic tract all can be exposed and observed well via transcallosal-septum pellucidum-interforniceal keyhole approach. (4) The interspacesⅠ,Ⅱ,Ⅳare well exposed via the supraorbital keyhole approach, the interspaceⅢis not exposed so adequately. The optic nerve, pituitary stalk, diaphragma sellae, optic chiasma, bilateral ICA and PcoA, antepituitary are observed well via the interspaceⅠ. The ICA, PcoA and its branches are observed via the interspaceⅡ. Bilateral Posterior cerebral artery, basilar artery and its barnehes, supracerebellar artery, oculomotor nerve can be observed by separating Liliequist membrane via the interspaceⅢ. By retracting the gyrus rectus, ACA, AcoA and Heubner artery can be observed via the interspaceⅣ. (5) All the four interspaces can be well exposed via pterional keyhole approach, especially for the interspacesⅡ,Ⅲ. When we want to expose the interspacesⅠandⅣ, the angle of attach must be inclined. Trans that approach from side, ICA, PcoA and AchA and their branches can be observed more elearly. There lack perforators between PcoA, oculomotor nerve and tentorium, bilateral Posterior cerebral artery,basilar artery and its barnehes, supracerebellar artery and oculomotor nerve can be obsevred by separating Liliequist membrane, and ventral lateral brain stem can aslo be obsevred. To enter the interspaceⅣoften need ressecting gyrus rectus. (6) The interspaceⅣis well exposed via transcallosal-septum pellucidum-inter- forniceal keyhole approach, but others are not.Conclusion:(1)The exposure for sellar area is different of those sugical approach,the exposed area of the pterional keyhole approach is the lagest,the supraorbital keyhole approach is the second, and the transcallosal-septum pellucidum-interforniceal keyhole approach is the minimal.(2)The important struetures such as nevres and vessels of the sellar area can be obsevred under neuroendoscope assisted microscope via supraorbital and pterional keyhole approach, including the ventral brain stem and basilar artery. The struetures of suprasellar and the anterior third ventricle are well exposed via transca- llosal-septum pellucidum-interforniceal keyhole approach.(3) Neuroendoscope is a tool that has widely visual field, large depth of field, the endoscopic field of vision is in the prolongation of the axis, and can eliminate the dead zone under the microscope. In the experiment,neuroendoscope can be used to observe the whole hidden anatomic structures via the constrictive interspace but not need to drag the important structures, also can observe the impalpable structures especially slim artey clearly. It is better than the microscope. (4)Every approach has it's advantage. The interspacesⅠ,Ⅳof sellar area and the anterior of Willis circle can be well exposed via supraorbital keyhole approach. The angle of attach is straightly, the structures in midline,ipsilateral and partly contralateral site can be exposed sufficiently.All the four inter- -spaces,suprasellar,ipsilateraly,posteriorly and the Willis circle can be well exposed via pterional keyhole approach, the exposure for the interspacesⅡ,Ⅲis its'most prevalent. For the whole PcoA and it's impalpable branches can be observed diretly via pterional keyhole approach. The interspaceⅣis exposed directly via transcallosal-septum pellucidum-interforniceal keyhole approach, the struetures of suprasellar and the anterior third ventricle are well exposed.