The Sectional Imaging Anatomy Of Trigeminal Nerve Root And Its Surrounding Vessels And Application In Microvascular Decompression For Trigeminal Neuralgia

ObjectiveTo provide the sectional imaging anatomical basis for microvascular decompressionfor trigeminal neuralgia through studying the sectional imaging anatomy of the trigeminalnerve root and its surrounding vessels and operation simulation for mastering complexanatomy of the trigeminal nerve root and its surrounding vessels.Material and MethodsTo collect12(male9, female3) head specimen of the Chinese adults. The transversal,sagittal and coronary sectional specimen of8mm was obtained with an electric band sawaccording to equal distance. A male head specimen were sliced into0.2mm continuoussectional images on transversal plane from low plane to high plane with SKC500typecomputerized miller which has the accuracy of0.001mm. To collect10healthy volunteers(male8, female2). The transversal, sagittal and coronary MR images were obtained by GESigna HDe1.5T systemic MRI scanners and AW4.4type image post-processingworkstation.2head specimens were used in trigeminal neuralgia microvasculardecompression simulating surgery after obtaining CT and MRI images. To clarify complexanatomy of the trigeminal nerve root and its surrounding vessels through contrasting thicklayer and thin layer specimens with CT and MRI images and combining head specimenoperation simulation results.ResultsThe transverse sectional anatomy of pituitarium and upper Sphenoid sinus displaysthat the origin of bilateral trigeminal nerve root is visible at the border of outboard basilarpart of pons and medipeduncle. Trigeminal nerve rans before bottom of pontine cistern and finally turns into trigeminal ganglion which locates in meckel cavity.The midsagital planeanatomy shows trigeminal nerve root proceeds from medipeduncle and forms trigeminalganglion in meckel cavity,sphenoid sinus lays below and anterior.The coronal sectionalanatomy of the optic chiasma and pituitarium reveals trigeminal ganglion in the meckelcavity locates in lateral of bilateral internal carotid,goes downward through ovalforamen,and then changes into mandibular nerve.Trigeminal nerve root and surroundingblood vessels:mainly include superior cerebellar artery,anterior inferior cerebellar arteryoppress trigeminal nerve root，of the two,the former is the most commonplace, especiallyoppression of dorsal part. The surgical simulated result evinces that too low position offenestration will result in too high upper surface of cerebellum which is not useful toexpose trigeminal nerve root and surrounding blood vessels.In the lateral decubitusposition,the upper limit of fenestration is transverse sinus,the outside borderline is theposterior limit of sigmoid sinus.The brain spatula should be pressed down and front asmajor and be pushed inside slightly in cerebellum so as to make sure trigeminal nerveroot and surrounding blood vessels can be revealed clearly.The knowledgeabove-mentioned has been applyed well in decompression operation of10cases withprosopalgia.Conclusion(1)The transverse and midsagital plane sectional anatomy of pituitarium and uppersphenoid sinus is typical to identify pontine cistern section,ganglion and meckel cavity oftrigeminal nerve root.The coronal sectional anatomy of the optic chiasma and pituitariumis representative to distinguish trigeminal ganglion and mandibular nerve.(2)The bloodvessels to oppress trigeminal nerve root mainly include superior cerebellar artery,anteriorinferior cerebellar artery, the former is the commonest,and the oppression usually comesfrom dorsal part.(3)The operation to cure prosopalgia should be implemented after thecapillaries decompression of sigmoid sinus.The position of posterior fossa fenestration hasaffinities with the standard display of trigeminal nerve root.the fenestration position can’tbe done too low,which is the best way to prevent high upper surface of cerebellum and thefailure of exposing trigeminal nerve root. What’s more,the best way to reveal trigeminalnerve root and surrounding blood vessels clearly is to press the brain spatula downward.