Endoscopic Anatomy Research Of Ⅴ, Ⅶ, Ⅷ And Ⅸ Cranial Nerves And Microvessels Related To Keyhole Approach

BackgroundTrigeminal neuralgia, hemi-facial spasm, vestibular dizziness andglossopharyngeal neuralgia all belong to cranial nerves' disease.MVD has becomethe most effective method, as microvascular compression is considered as the primarycause.Endoscope-assisted surgerybecome significant part of modern minimallyinvasive neurosurgery. the disadvantage of MVD is: non-expandablespace ,deep-location, multiple neuro-vessel structure..responsive-vessel are not easilyidentified ,and visualization provided by the microscope alone is not enough .with thefine-vision and high resolution ,the endoscope is a useful adjunct to MVD.ObjectiveTo explore the feasibility of MVD through the same"keyhole',providing the anamotomy evidences for curing Trigeminalneuralgia hemi-facialspasm ,vestibular dizziness and glossopharyngeal neuralgia. 1,Adult cadaver brain(n=10),through standard restrosigrnoid keyholeapproach ,under 30-degree endoscope control ,to mimesis MVD. A 3cm to 2.5cmretrosigrnoid craniectomy was made inferior to the junction of the transverse andsigmoid sinuses ,CPA was identified by gently retracting cerebellum .,after CPA wasexplored with the microscope ,a endoscope was placed into the root entry zone toenhance the view of SCA,AICA and PICA ,and took photograph records .1)the nerveroots and micro-vessles were observed under microscope and recorded 2) the nerveroots and micro-vessles were observed under microscope ,with endoscope-assistedand recorded.the objective is to obtain clear view under endoscope control;toaccuracily measure the distance from middleline of sigmoid sinus posterior edge tothe nerves' root ;to achieve MVD by placing Telflon sponge between the vessel andthe nerves and record.2 the results was recorded as mean±SDResultsTrough retrosigmoid approach,with 3cm to 2.5cm keyhole ,the endoscope offereda panoramic view to identify the neurovascular conflict .gap 1:clear view ofNerve-tract (Ⅶ,Ⅷ),internal auditory foramen, trigeminal nerve ,petrosalvein ,trochlear nerve and SCA under endoscope gap 2: clear view of internal auditoryforamen ,jugular foramen, cranial nerves(Ⅶ,Ⅷ,Ⅸ,Ⅹ,Ⅺ),labyrinthincartery ,AICA ,PICA and abducens nerve under endoscope gap3: clear view ofpost-cranial nerves,PICA ,basilar artery and foramen magnum under endoscope .aTeflon sponge was inserted between the cranial nevers(Ⅴ,Ⅶ,Ⅷ,Ⅸ)andmicrovessels Conclusions1)Keyhole approach provides enough operating space for microvasculardecompression2)the same retrosigmoid keyhole approach can be used in the therapy ofⅤ,Ⅶ,ⅧandⅨcranial nerves.3) An endoscope can be used to enhance the visible field and provide enoughlighting of deep structures, which is important for us to identify the responsiblevessels and place Teflon cotton and reduce complications.