Observations On Anatomic Changes Of Opticocarotia Triangle In Operations By Pterional Approach

Objectives:Opticocarotia triangle,which is usually called SpaceⅡ,is frequently used in operations to treat diseases in sellar region or around it.The Majority of practitioners know SpaceⅡby reviewing anatomic documents from observations of adult cadaver heads.In fact,there are some anatomic changes around sellar region which result from tumors or other diseases,which may disturb thoughts and operations of neurosurgeons.In order to make neurosurgeons acknowledge these abnormal anatomic changes and take the problem into their cosideration,we took this project so that neurosurgeons can widen their views and develop their levels in diagnosing and treating patients.Methods:We operated under microscope with 6-25 manification through pterional approach to treat 32 patients with diseases around sellar region.In these operations we all exposed SpaceⅡand some diseases were treated through it.We saved videos with digital system and caught pictures to review anatomic changes.We detected the longest and widest distances and the diameter of each ICA in every pictures,then we counted ratios between the longest distance and the diameter of ICA and those between the widest distances and the diameter of ICA in each pictures.We compared these ratios of each patient in three stages—preoperation stage,midoperation stage and postoperation stage to study SpaceⅡ.At the same time,we studied these operational videos to describe anatomic structures involved with SpaceⅡto direct our operations.Results:SpaceⅡis classified into three types—triangle type,fusiform type and obsolete type.Among all SpacesⅡin the 32 cases in preoperation stage,about 51.4%were triangle type,17.2%fusiform type and 31.4%obsolete type.About 1/3 of 32 cases belong to obsolete type which has been known rare,however,about 62.9%triangle type,22.9%fusiform type and 14.2%obsolete type after operations because of being released from tumors.In midoperation stage,the longest and widest distances of space two increased,so did the areas of spaces two.In one operation,we found a tissue seemed as PcoA in SpaceⅠ,which was verified to be ICA of the opposite side.It was wrapped and pushed to endoinferior side.In another two patients' heads,the chiasm opticums were found fat and flat.We succeed to cut tumors through bilateral SpaceⅡ.We removed the anterior clinoid process to magnify the SpaceⅡto treat a huge aneurysm from ophthalmic artery successfully.We can observe pituitary chalk,PCoA,SHA,PCA, BA and oculomotor nerve through SpaceⅡand try our best to protect them during the operation.Conclusion:Triangle type SpaceⅡis the most common,there are less fusiform type SpacesⅡand obsolete type SpaceⅡare the least.SpaceⅡcan become smaller or obsolete,which results from tumors.And it can be recovery after operation. Being pulled in operation,SpaceⅡcan be prolonged in length by 1-3 times and widen in width by 1.5-4 times.As a result,its area becomes larger.It is unsuitable to pull ICA of a patient with aneurysm or anteriosclerosis in order to avoid hemorrhage that is difficult to treat.The removal of the anterior clinoid process can help to magnify the SpaceⅡ,which is benefit to operation.Don't try to cut the whole tumor until the important anatomic structures are exposed.It is better to cut tumor gradually by little parts than cut it at one time blindly so as to avoid injury of important blood vessels and nerves,such as ICA in abnormal position,in SpaceⅡ.It is a good choice to cut tumor through SpaceⅡwhen the optic chiasm is a fore-lying one.Cutting tumor through bilateral SpaceⅡcan help a lot if the chiasm opticum was found fat and flat.