Research Of Anatomy And Surgical Strategy In Sclerotin Removal In Apical Petrous Regions

Objective: In this study,through microdissection of apical petrous and peripheral regions in head specimens,providing the anatomy basis of sclerotin stripping;Also,through the simulation of kawase approach and posterior-internalauditory canal approach of sinus sigmoideus,the safety range and operability of sclerotin stripping will be understood and the range of application of both approaches will be investigated.Methods:1 Research of Dissection in Apical Petrous and Peripheral Regions:For blood vessels of head specimens,after colour silica gel`s perfusion, related anatomic landmark in apical petrous regions is viewed in different angles with 4-25 x dissecting microscope to measure the relationship between relational anatomical structures in apical petrous regions before and after removing Kawase triangle,including specifically the relationship between the anatomy location of Kawase triangle,petrous bone segment on internal carotid and the apical petrous regions to measure the correlation distance between petrous bone segment in internal carotid,cochlea,trigeminus.2 Operation Simulation of Sclerotin Removal in Apical Petrous Regions:For blood vessels of head specimens, after colour silica gel`s perfusion, the kawase approach under 4-25 x dissecting microscope is simulated to measure the exposed differences of slope before and after removing the kawase triangle sclerotin,to discuss the affectiveness of the kawase approach for the expose of tumors in the petroclival region;using the maximum grinding method to make the anterior margin and inferior margin of bone window achieve the ICA and cochlea, inferior margin achieve the inferior petrosal sinus,and the related statistics are measured,to discuss the maximum safety range of sclerotin appropriate to be removed in this approach.In the head specimen from another blood vessel perfused by colour silica gel,under 4-25 x microscope,the retrosigmoid-suprameatal approach is simulated,nodules on the internal auditory canal and apical petrous regions are removed to sufficiently expose Meckel`s cave and internal carotid in apical petrous of bone segment, measuring and photographing the important structures referred in the operation to understand the maximum safety range of sclerotin appropriate to be removed in this approach; to discuss the safety and operability of such approach.Results:1 In research of the anatomy of apical petrous,the distance between the important structures of petrous apex area are measured,the results are as follows(using the statistical mean plus or minus standard deviation description in SPSS 16.0):The distance between cochlea and lateral border of trigeminus is(11.75±2.29)mm;The distance between trigeminuslateral border and the foramen lacerum of internal carotid is(14.38±1.55)mm.2 In the operation Simulation of Sclerotin Removal in Apical Petrous Regions,the results as follows show the important statistics in Kawase approach(using the statistical mean plus or minus standard deviation description in SPSS 16.0):The length difference between removed apical petrous regions in Kawase approach and the exposed slope of after cutting tentorium of cerebellum is(7.63 ± 2.43)mm;Removed depth of Kawase triangle is(11.6±0.14)mm.3 In the operation Simulation of Sclerotin Removal in Apical Petrous Regions,the results as follows show the important statistics in retrosigmoid- suprameatal approach(using the statistical mean plus or minus standard deviation description in SPSS 16.0) The perpendicular distance between margo inferior of bone window and ICA C2 in retrosigmoid- suprameatal approach is(2.06±1.33)mm;The racial length before and after removing bone window in retrosigmoid-suprameatal approach is(21.95±2.23)mm.Conclusion:1 The Kawase approach can increase expose range significantly of the superior and middle slopes,the effective exposure range is midcourt line reaching the superior and middle slopes in the front,the facies lateralis of anterior pontomesencephalic regions,the posterior reaches facial and auditory nerve,cerebellopontine angle region,the inferior and inferior reach the upper medulla oblongata,vertebral artery and the transitional position of basilar artery,the posterior and inferior reach the upper of facial and auditory nerve.2 The maximum front and back long diameter of Kawase approach after removing bone window is approximately 25 mm,the depth is approximately 11.6mm.In order to avoid the injury of internal carotid,cochlea,inferior petrosal sinus and abducens,the front and back diameter of bone window should not exceed 20 mm,and the depth should not exceed 10 mm.3 Indication of Kawase approach:Absolute indication: for tumors in brainstem ventrolateral medulla,central and upper slope regions, with or without the invation of cranial fossa;Relative indication: for the extension of CPA zone, reaching the posterior or lower lesion of facial and auditory nerve;or tumors extending downward to the medulla.4 The exposed maximum range of retrosigmoid- suprameatal approach: The anterior reaches the foramen segment of internal carotid artery and the posterior of cavernous sinus,the posterior-lateral reaches the lateral border of Meckel`s cavity,the upward side reaches trigeminus,the inferior reaches the ligature level between the superior border and abducens of facial and auditory nerve.5 In retrosigmoid- suprameatal approach,the saddle region can be exposed significantly,the lower limit of removal of the front-end petrosal bone should be limited in the upward side of ligature between the superior border of facial and auditory nerve and the abducens,the anterior and posterior diameter of removing bone window should not exceed 20 mm,therefore it may greatly decrease the probability of injuring petrous bone segment of internal carotid during removal.6 Indication of retrosigmoid- suprameatal approach:Absolute indication:1 The tumour is primarily the posterior cranial fossa(Growing from CPA to petroclival region),only a little infiltration in Meckel’s cavity,with or without neuronavigation exists during operation.The tumour is mainly growing to the posterior-lateral of Mechel`s cavity,the anteromedial margin of Meckel`s cavity has no obvious tumor infiltration.2 The tumour is primarily the posterior cranial fossa(Growing from CPA to petroclival region), with infiltration from Meckel`s cavity to middle cranial fossa,the patient has obvious pressured brainstem and trigeminus,however,his body has bad general condition,or he is older and cannot bear secondary craniotomy,or his relations refuse secondary craniotomy,do not require full-cut tumour and only require attenuated symptom.Relative indication 1:The tumour is primarily the posterior cranial fossa(Growing from CPA to petroclival region),only a little infiltration in Meckel’s cavity,and the tumor invasion exists in anteromedial margin of Meckel`s cavity,without neuronavigation exists during operation.Contraindication 1:Although the tumour body is located in posterior cranial fossa,there is much infiltration in middle cranial fossa,reaching cavernous sinus,the patient is young and his physical condition allows the secondary craniotomy,or the patient has the appeal of full-cut.