Microsurgical Anatomy Of The Superior Wall And Lateral Wall Of The Cavenous Sinus

BackgroundUntil 1965,when Parkinson's landmark article describing the direct surgical approach to carotid cavernous fistulas was published,little reference was made in the neurosurgical literature to direct operative attack on lesions of the cavernous sinus.This lack of information was largely a result of the inability in the premicrosurgical era to effectively deal with the extreme risks of significant hemorrhage and damage to the cranial nerves in the region.This anatomic locale has long been considered a true "no man'land" for direct surgical approaches.The modern era of micronerurosurgery has realized expanded capabilities in microsurgical technique and has fostered the work of several neurosurgeons who have made great strides in effectively approaching this region with reduced morbidity.In particular,the work of Dolenc should be recognized for the development of his combined epidural and subdural approach,which has become the standard method used to treat lesions in this region.ObjectiveBecause of the little data about CS'lateral wall,superior wall and interior cranial nerve and blood vessel,we had researched the region anatomy.The purpose of study was to provide the base of anatomy for designing the CS'operation approach and avoiding the lesion of cranial nerve and ICA,by exploring the morphology characters and microdissection structures of CS's lateral wall and superior wall.Material and Methods: 1,Material:20 cases(40 sides)Chinese adult cadaver heads fixed by 10%formalin.Red latex was injected into arterial systems.2,Instrument:neurosurgery micrurgy instruments,headframe,operation microscope,compasses,sliding caliper,Ricoh photographic accessory.3,Methods:20 cases(40sides)Chinese adult cadaver heads fixed by 10% formalin was choosed.Cranial bones were sawed off from the deviding line between cranial base and skull cap.Brain stem was cut from mesencephalic superior extremity and cerebrum and interbrain were dislodged completely.Arachnoid mater in saddle area was cleared up. Reservation of 2～4duplet cranial nerve,stalk hypophysial and ICA were very important.All specimen from measure under microscope.4,Statistical treatment:All data were statistically processed and presented in the mean style.Results:1,The superior wall of CS includs Dolenc triangle,Hakuba triangle,carotid triangle and oculomotor triangle.2,The length of each side of the Dolenc triangle is(6.30±1.54)mm, (10.02±2.44)mm,(11.03±1.85)mm.3,The anterior clinoid process is made up of cortical bone and cancellous bone.It has the air cells,in 10%of the 30CSs.4,The distal dural ring is a thick membrane that fuses with the adventitia of the ICA and its thickness is(0.52±0.07)mm,The proximal dural ring loosely surrounds the entire length of clinoid segment of ICA and admits a variable number of veins from the cavernous plexus that accompany this segment.The thickness of the proximal dural ring is(0.22±0.06)mm. 5,The length of each side of the Dolenc triangle is(7.69±2.07)mm,(7.25±2.02)mm,(4.25±1.38)mm.6,There are Parkinson triangle,paramedical triangle,Mullan triangle,Lateral triangle,Glosscock triangle and Kawase triangle are in the lateral wall and its surrouding.7,The length of each side of the Parkinson triangle is(17.26±3.07)mm, (14.26±3.91)mm,(5.61±2.56)mm8,The length of each side of the Glasscock triangle is(12.41±2.40)mm, (14.15±2.74)mm,(6.85±2.16)mm.9,The length of each side of the Kawase triangle is(14.99±2.75)mm,(12.94±2.40)mm,(11.25±3.45)mm.10,The length of oculomotor nerve,trochleator,ophthalmic nerve in the CS is (8.19±0.93)mm,(10.16±1.12)mm,(16.23±2.24)mm.Conclusions:1,Removing the anterior clinoid process is a key step through the superior wall of the CS approach,we should also notice the osseous variaton in this region and pay attention to the grinding range and metheds.we should limit the range in the Dolenc triaangle.2,There are no important anatomic structure in the Hakuba triangle.Discssion this triangle and entering the Cavernous sinus is safe.3,For exposing the clinoid segment of the ICA should cutting the distal dural ring from its medical margions.4,The trochear courser is important to the Parkinson triangle. 5,Grinding the Glasscock triangle can expose the os petrosum segment of ICA,so ICA can be blocked.6,Grinding the ossea of the Kawase triangle can expose clivus from the floor of the middle cranial fossa and come into posterior cranial fossa.7,It is helpful knowing the serve to the important structures during the Dolenc approach.8,The operation approacanatomical characteristics of tissues and structures in the superior wall and lateral wall of CS to perh of CS can not iminate Dolenc approach absolutely,but be choosed according to different conditions.