Study On Sella Region Anatomy Of Endoscopic Endonasal Trans-sphenoidal Removal Of Tumor In Sella Region

Objective The objective of the study is to explore the important anatomical mark point and its characteristics in sella region,through the comparative analysis of sella region cross-sectional anatomy and neuroendoscopic endonasal trans-sphenoidal surgical anatomy.In clinical practice,neuroendoscopic endonasal trans-sphenoidal removal of the tumor in sella region can possibly result in the serious complications of 'fatal bleeding caused by injury of the internal carotid artery and cavernous sinus' and 'blindness caused by injury of optic nerve or optic chiasm'.In order to avoid these complications,in addition to improve the equipments,proficiency in neuroendoscopic endonasal trans-sphenoidal surgical anatomy is of great importance.Although neuroendoscopic endonasal trans-sphenoidal removal of the tumor in sella region shows its perfect features,it also has some weaknesses.It provides two-dimensional images which lack three-dimensional effects. However,cross-sectional anatomy in sella region can provide continuous anatomic slices of the specific site,and help the operator to develop the idea of three-dimensional anatomy of sella region. Understanding the three-dimensional anatomic relationship of important structures in sella region can play a guiding role for endonasal trans-sphenoidal removal of the tumor in sella region in practice,and provide anatomic basis for improving its success rate and safety.MethodsThe first part:Heads from 12 adult cadavers embalmed by formalin solution were used as materials.Procedures included:①specimen decalcification:the materials were immersed in 10%hydrochloric acid for 7～15 days,until the bone tissue can be pierced by needle;②flushing:the specimen was taken out and flushed by circulating water for 24 hours;③routine method of dehydration:the specimen was dehydrated step by step,until it became hard;④immersion in celloidin:dehydrated specimen was immersed in 5%celloidin, vacuumized for 30 minutes using 66 kPa in vacuum drying oven, vaccumized again after one-day standing.And once again after one-day standing,the specimen was immersed in 8%celloidin,and vaccumized twice under the same condition.⑤making embedding block:15%celloidin was used as embedding medium,it took about 15-30 days to make embedding block,and then the embedding block was hardened and stored in 70%alcohol;⑥making slice:the researcher used L-type cerebral microtome made in German to make continuous slices of the specimen,whose thickness was set at 0.5～1.0mm.The second part:Heads from 6 adult cadavers embalmed by 10%formalin solution were used.The researcher imitated endonasal trans-sphenoidal surgical approach,and used KARL STORZ neuroendoscopy system to observe and document the anatomic structure of nasal cavity,sphenoid sinus,and intracranial sella region.The researcher also observed anatomic structure of surgical region,in particular,the sella region and its surrounding structures, identified some important surgery-related marking points,and measured and analyzedResults Cavernous sinus is a venous channel filled with blood, and divided into 4 major spaces,i.e.inferior-anterior, superior-posterior,medial and lateral,among which superior-posterior part is the largest,while lateral part is the smallest.And there are still a few veins in cavernous sinus.The lateral wall of cavernous sinus can be divided into superficial and deeper parts.The superficial layer is compact endocranium.The deeper part is loose connective tissue,where oculomotorius, pathetic nerve,nervi ophthalmicus,and superior maxillary nerve go through.In addition,77.28%of the specimens have sinuses venosus between two layers of lateral wall of cavernous sinus;The area of cavernous sinus and other indicators in coronal slices gradually become larger from anterior to posterior part,among which the area of middle part of pituitarium anterius or pituitary stalk is the largest, and then gradually became smaller;The aperture of sphenoidal sinus is the most important mark point,which is located at spheno-ethmoic recess at the superior posterior part of superior nosepiece.Although spheno-ethmoic recess is always an existing structure,its conformation varies greatly,so it can not be used as a very reliable anatomic mark point;In most cases,the middle septum of sphenoid sinus is not in the median line,but deflected to one side, and mostly to the left side,as a result,it can not be regarded as the mark point of the median line in endonasal trans-sphenoidal removal of the tumor in sella region;The study preliminarily demonstrated that the vacancy or weakness of one side or two sides of the sella turcica may be used as the channel,through which the tumors in sella region develop from it toward areas around it.The weakness or even vacancy of medial wall of cavernous sinus is the anatomic basis for the encroachment on cavernous sinus by pituitary adenoma.Conclusions Continuous anatomic slices in the local tissue of sella region made by using the technique of celloidin embedding provided anatomic information about the continuous slices of the specific area,and played a directing role for endonasal trans-sphenoidal removal of the tumor in sella region in clinical practice.When using endonasal trans-sphenoidal approach,the neuroendoscopy can provide a panoramic operating field and better exposure of sphenoid sinus and basis cranii in sella region.From anatomic perspective,the neuroendoscopic endonasal trans-sphenoidal approach can treat most of the pathological changes in sella region which previously must be treated through transcranial operation.The advantages of this operation approach include the following:not using craniotomy,avoiding traction of brain tissue and accompanied damage of nerves and blood vessels and other structures,and being of great significance for protecting important nerves and blood vessels during operation.