Anatomic Study And Clinical Application Of Precise Location And Grinding Of Kawase Triangle In The Intradural Anterior Subtemporal Transpetrosal Approach

Object:Using the advantages of the dry skull specimens,to explore the method of accurately locating related bony structures and safely grinding out the Kawase triangle bone in intradural anterior transpetrosal approach,and verifies it by wet skull specimens,so as to provide anatomical basis for clinical application.Method:1.Craniometric measures were taken from 15 adult skulls.The highest point of the arcuate eminence(point A),the most lateral point of the groove in the greater superficial petrosal nerve(point B),the most lateral point of the foramen spinosum(point C),the most lateral point of the foramen ovale(point D),the most lateral point of the trigeminal impression(point E),the most lateral point of the foramen lacerum(point F)and the petrous apex(point P)were marked.The distances between AB,AC,AD,AE and AF were measured.Using the AP line as the baseline,the acute angles between the baseline and the lines of AB,AC,AD,AE,and AF were measured.And then,the locating method was further verified by imitating the intradural anterior subtemporal transpetrosal approach in 5 cadaveric specimens.The accuracy of and satisfaction with the exposure of the related petroclival structures were evaluated in the surgical region.2.On the 16 dry skulls,the intersection of arcuate eminence and petrous ridge(G),the intersection of arcuate eminence and groove for the greater petrosal nerve(H),the intersection of mandibular nerve and groove for the greater petrosal nerve(I),the intersection of trigeminal impression and petrous ridge(J),the top edge of intern alauditory canal(K)and the intersection of vertical line crossing point K of petrous ridge(L)were marked.The distances of GH,HI,IJ,JG and KL and the area of GHIJ were measured.Samples were analyzed by mean and standard deviation,and the data obtained from the above experimental measurements on both sides were compared by t test.At the sometime,five dry skulls were selected to grind the related petrous bone for verifying the statistical data of above experiment.And three wet skulls were selected to simulate removing the related petrous bone in intradural anterior transpetrosal approach for further verifying the above experimental data and observing the surrounding exposure structure.Result:1.The distances between point A and related bony structures were as follows:AB:11.54±2.27 mm(left),10.43±1.92 mm(right),t=1.443;AC:22.31±2.31 mm(left),20.92±2.45 mm(right),t=1.600;AD:25.57±2.54 mm(left),24.71±3.08 mm(right),t=0.834;AE:19.38±2.84 mm(left),19.35±2.60 mm(right),t=0.035;and AF:29.96±2.456 mm(left),29.35±2.49 mm(right),t=0.673.The acute angles between the baseline and the lines of AB,AC,AD,AE,and AF were as follows:?BAP:51.54±10.83°(left),53.37±12.53°(right),t=-0.427;? CAP:45.12±7.17°(left),47.84±7.02°(right),t=-1.050;?DAP:39.91±5.15°(left),42.02±3.55°(right),t=-1.309;?EAP:24.95±6.77°(left),26.60±6.27°(right),t=-0.694;and?FAP:16.19±3.02°(left),17.45±3.44°(right),t=-1.068.There were no significant differences between the measurement results on the left and right sides(P>0.05).On the basis of the anatomical data of the skulls measured above,related petrous bony structures can be located accurately using an imitation of the intradural anterior subtemporal transpetrosal approach on cadaveric specimens,According to related bony structures,the neural and vascular structures can be precisely positioned in the surgical area.The related petroclival structures can also be exposed satisfactorily in the operative region.2.Measurements of dry skull specimens:GH:14.04±1.61mm(left),13.82±1.44mm(right),t 0.403;HI:14.00±2.22mm(left),14.86±1.99mm(right),t-1.15;IJ:13.48±0.97mm(left),13.64±1.4mm(right),t-0.38;JG:17.18±1.71mm(left),17.17±2.29mm(right),t 0.01;KL:4.77±0.54mm(left),4.71±0.72mm(right),t 0.239.S-GHIJ:208.25±27.67(left),214.35±37.95(right),t-0.519.There were also no significant differences between the measurement results on the left and right sides.With the experimental data,the related petrous bone in the dry skulls could be removed safely,and no structural damage such as cochlea,semicircular canal and internal auditory canal was found.In the intradural anterior transpetrosal approach,the measurement data can be used to grind the related petrous bone on cadaveric specimens without damaging the peripheral nerves,blood vessels and functional structures.The upper wall of the internal auditory canal can be further removed,and the internal auditory segment of facial auditory nerve can be seen.Conclusion:1.Using points A and P as referential anatomical landmark points,the correlative bony structures representing the corresponding nerves and vessels can be accurately located to safely grind the bone of Kawase's triangle using an intradural anterior subtemporal transpetrosal approach.This method can ensure safe,accurate and rapid drilling of the anterior petrosal bone to expose the petroclival region satisfactorily in the surgical area.2.In this study,the dry skulls were selected as the research sample,and the practicability and safety of the dry skull and cadaveric specimens were verified,which provided the anatomical basis for the safe grinding range and the maximum grinding depth of Kawase triangle in the intradural anterior transpetrosal approach.