Anatomical And Clinical Studies Of Keyhole Approach And Minimally Invasive Neurosurgery

Background and objectiveKeyhole technique,coming from skull base approaches,is an important pattern ofmanifestation of mini-invasive neurosurgery, and it will be a reforming process offormer traumatic skull base surgery.Neurosurgery keyhole technique had been carriedout oversea for several years,and was introduced to home years ago.Though it isinvolved in plenty of surgery, none of other new technique had been gotten sucharguments as keyhole technique.The causes were that former studies were mainlyabout keyhole surgery could be used in what case,what surgery, or it's result.The studyabout surgical difficulties and risks in condition of "key type" bone hole is scarce.Theapplication of keyhole technique is dispute all the time because of little knowing ofkeyhole surgery's limited factors,not enough of individual scheme,no stem surgicalindications,inner limitation of bone hole and keyhole surgical risks.We undertookanatomical and clinical studies of keyhole approaches in the view of considering it'slimited factors that would influence keyhole surgery, so as to better understand andutilize the technique.According to related reports and theories of keyhole,we classified keyholemini-invasive operative approaches into two subtypes:Type one(changelesskeyhole): Keyhole approaches that utilize intra-cranial exiting natural interspace andthen magnify deep space during operation.Type two(changeful keyhole):Keyhole approaches that intracerebral lesions are close to bone hole,or that lesions in brainparenchyma can't be exposed unless part brain tissue is slitted.The anatomy limitedfactors consisted mainly of the scope and place of bone hole,utilization degree ofarachnoid membrane space and the depth between skull bone and lesions.The limitedfactors during operation consisted of deviation between before operative imaging andactual information during operation,selection of different keyholeapproaches,operator's abilities of treating risks, assistant's matchingabilities,influence from nerves and vessels,et al.During such frequent emergenceoperation as aneurysm disruption, hypertensivc cerebral hemorrhage and epiduralhematoma,the utilization of keyhole technique was usually limited due to intracranialhypertention,brain edema and even cerebral hernia.In this study,we analysized andcompared the data from anatomical dissections and data from computerized CT andCTA three-dimensional reconstruction anatomic measurement.At the same time,westudied keyhole and mini-invasive technique about changeless keyhole approach andemergency opration,especially intracranial aneurysm,hypertensive cerebralhemorrhage and epidural hematoma.The purposes of the studied consisted of: 1 The anatomical studies of transupper of orbit,trans lateral of front,trans pterion and trans sub-temple keyholeapproaches were carried out by way of bones of skull samples,micro-anatomy and CTand CTA 3D -reconstruction.The results were compared with skull base3D-reconstruction to further systematize and consummate the anatomy of keyholeoperative approaches.The study results would help to design surgical scheme,estimateintra-operative difficulties and risks,and to analog treatment abilities.Becausedifferent operative angles and realms, in trans upper of orbit,trans lateral of front,transpterion and trans sub-temple four keyhole approaches,the size and appearance of orbitroof cerebral juga and frontal sinus,the anatomic appearance and angle of ridge of spenoidal bone,sellar region,anterior clinoid process, arcus zygomaticus and middleskull base changed greatly.Thus,changes of these four keyhole approaches's anatomicstructures could be described in detail,helping to guide skull base opreation and sellarregion operation through keyhole approaches.2 The clinical objective of the studywas:(1)To study and evaluate the methods,requirement,limited factors and value ofchangeless keyhole mini-invasive operative approach in treatment of intracraniallesions.(2)To study the aneurysm disruption risks during operation,and analysize thelimited factors,proper selection of surgical indications,operativedifficulties,prevention and treatment of intra-operation aneurysm disruption inemergency keyhole surgery.(3)To evaluate the mini-invasive surgical treatment andits' limited factors in hypertensive cerebral hemorrhage.Materials and methods1 Measurements of bone desection samples and cadaver head samples1.1 Sixty-seven adult skull bone samples were selected and sawed in supraorbital archand in the level of anterior skull base.We then inspected the opening of frontalsinus,observed the appearance of orbit roof cerebral juga,and measured the highestheight of two cerebral juga.1.2 The distances and angles between ipsilatral anterior clinoid process and posteriorclinoid process through trans upper of orbit,trans lateral of front,trans pterion andtrans sub-temple keyhole approaches in 15 skull bone samples were measured.1.3 The fontal sinus left and right length and anteroposterior dimension width wasmeasured in 62 normal cerebral CT imagings.1.4 The distances and angles between the opening of cranium and bifurcation ofinteral carotid artery,between the opening of cranium and anterior communicatingartery,were measured by former four keyhole approaches in 10 formalin-fixed adult hygro- cadaver head samples.1.5 Operative procedures were simulated through former four keyhole approaches in10 formalin-fixed adult hygro- cadaver head samples and 3 fresh adult cadaver headsamples.2 Computerized CT and CTA 3D-reconstruction studies of keyhole andmini-invasive operative approachesFifteen volunteers,including healthy volunteers and those needed to expludeintracranial diseases,undertook 16 lines spiral CT inspection.Ten clinical suspectintracranial aneurysm patients underment 16 lines CTA inspection.The inspectionparameters consisted of 140 kV,180ms,collimate width 0.75mm, 0.5s/r,layerthickness 1mm, reconstruction interval 1mm and visual field 18cm.The inspectionrange was from C1 to top of cranium.Reconstruction of 3D skull bone imaging and3D vessel imaging was completed by SIEMENS LEONARDO Syngo2003Asoferware.The reconstruction methods included in multiplanar reformation,maxiumintensity projection and volume rendering technique.Related measurement softerwarewas adopted to measure the height of cerebral juga, and concrete data is the distancesand angles between former four keyhole approaches and anterior communicatingartery,bifurcation of internal artery,top of aneurysm.3 Clinical studies of keyhole and mini-invasive operative approaches3.1 Thirty-three cases,which were operated by way of changeless keyholemini-invasive approaches during past three years,were analyzed retrospectively.Allthe diagnosis was verified by post-operative pathology,including 7 cases ofmenigioma,7 cavernous angioma,6 gradeⅠglioma,5 cerebral metastatic tumor,3 brainabecess,3 granuloma and 2 cases of brain AVM.3.2 One hundred and fifteen intracranial aneurysms were operated,partly by approaches of keyhole mini-invasion and partly by routine craniotomy,on the basis ofrisk evaluation.In the total of 43 keyhole craniotomy,pterional keyhole approacheswere introducted in 20,supra-orbit keyhole in 18 and trans longitudinal fissionkeyhole in 5 cases.Another 72 cases with high risk undertook routinecraniotomy,including routine pterional approaches in 31,sub-frontal in 11,translongitudinal fission in 7,pterion plus subfront in 10,pterion plus in longitudinal fissionin 6,subfront plus longitudinal fission in 7,petrion plus subfront and longitudinalfission in 3.3.3 To evaluate the minimally invasive surgical emergency treatments and strategiesin hypertensive intracerebral hemorrhage, 217 cases of hypertensive intracerebralhemorrhage,which were dealed with different surgical methods during a period of 5years,was studied retrospectively.4 Statistical analysisThe statistical analysis was performed with SPSS11.5 software package and thedata were presented with (Mean+Standard Deviation).As to the data ofhomoscedasticity,One Way ANOVA method was applied and comparation thedifference between two samples.In condition of heterogeneity ofvariance,multi-independent sample non-parametre method was introduced.Results1.1 Anatomic observation and measurements resultsOf all the 67 (134 sides) adult skull bone samples,52 sides got frontal sinusopenness,with the open rate 38.8%(52/134).The anterior skull base consisted mainlyof orbital roof plate,and the smooth and claw of skull base was determined by theappearance and height of cerebral juga.Most skull bases were clawed,mainlymulticuspidity and oblique ridge mulicuspidity.The height below 2.5mm was found in 36 sides(26.9%),and above 2.5mm in 98 sides(73.1%).The highest height of twosides cerebral juga was 2.76±0.43cm in left and 2.91±0.48 in right.Eighty-threesides(61.9%) had obvious sphenoid fovea pterygoidea groove.The distances and angles between the bone window centre outer plate andanterior clinoid process,posterior clinoid process was measured in 15 cases(30 sides).The fontal sinus left and right length and anteroposterior dimension width wasmeasured in 62 normal cerebral CT imagings. The distances and angles between theopening of cranium and bifurcation of interal carotid artery,between the opening ofcranium and anterior communicating artery,were measured by former four keyholeapproaches in 10 formalin-fixed adult hygro- cadaver head samples. Operativeprocedures were simulated through former four keyhole approaches in 10(20 sides)formalin-fixed adult hygro- cadaver head samples and 3 (six sides)fresh adult cadaverhead samples.We considered deep operative eyesight,narrow operative intervals andweaken intensity of illumination as the major limited factors.1.2 Results of the data of anatomic measurements in CT and CTAreconstruction and simulation results of keyhole approachesThe highest height of two sides cerebral juga was 2.76±0.43cm in left and2.91±0.48 in right,which is significantly different from measurements data frombones of cranium.The data of the distances and angles between the bone windowcentre outer plate and anterior clinoid process,posterior clinoid process in 15(30 sides)skull bone 3D-reconstruction samples had no difference compared with that of skullbone samples.The data of distances and angles between the opening of cranium andbifurcation of interal carotid artery,between the opening of cranium and anteriorcommunicating artery in 10(20 sides) CTA samples was also not significantlydifferent from that of formalin-fixed adult hygro- cadaver head samples.According to the results of CTA 3D-reconstruction simulation four keyhole operative approaches,different keyhole approaches had diverse effects on aneurismalexposing,prevention of the baffling of vessels and tissues. Thus,CTA3D-reconstruction simulation keyhole operative approaches could help to exposeaneurysm and offer best approach before operation.1.3 Results of clinical studies1.3.1 During the changeless keyhole approaches,22 cases was finished with the helpof routine CT location,5 with stereotaxis guided location and 6 with neuro-navigationguided location.Of all the patients,93.9% got total resection and subtotal removementin 6.1% of cases.Incision infection happened in 2 cases,but recovered well undertreatment.No dead cases was reported.1.3.2 As to the operation of intracranial aneurysm,in the group of keyholeapproaches,6 cases had aneurismal leaky, and disruption in 3 cases,with the incidencerate of 7.0%,no dead cases.Two cases changed to routine craniotomy becauseocclusion of aneurysm could not completed by way of keyhole approach.In the groupof routine craniotomy,18 cases had aneurismal leaky, and disruption in 9 cases,withthe incidence rate of 12.5%,and two dead cases were reported after operation.1.3.3 Of the patients with hypertensive intracerebral hemorrhage,22 underwentunilateral external ventricular drainge and bi-lateral external ventricular drainge in 31cases.And 39 cases got craniotomy hematoma cleaning plus external ventriculardrainge,61 cases of operation were finished by way of keyhole and small bonewindow(diameter not more than 5cm),stereotaxis guided hematoma evacuation wasapplicated to 12 cases,8 cases got posterior fossa decompression and another 12 plusoccipital angle external ventricular drainge,32 cases undertook simple big bonewindow craniotomy decompression. Totally,63 of 217 patients recovered, 71 had mildsequelae, 53 were severely disabled, 11 were persistently vegetative, and 16 died.Seven patients in the series worsened postoperatively because of rebleeding. Mostpostoperative complications were seen in older patients and in those with severeneurological deficit or chronic disease. Conclusions1 Measuring the size of frontal sinus will help to provide anatomic basis in selectingsuitable operation side,thus cutting down the rate of postoperative infection fromopening of frontal sinus.Measureing the height and appearance is benefial,in that itcan help to select operative approaches,prepare grinding drill and decide drillingdegree.2 Computerized CT and CTA 3D-reconstruction can show actual anatomicinformation of skull bone, intracranial vessel and tissue.Through before-operative3D-reconstruction,operators will know related limited factors and diffulties,selectoptimal operative approaches,identify the size and scope of skull base bonebaffling.And it will be helpful in skull base anatomy teaching.3 In conditions of selecting proper cases,changeless keyhole approaches have suchadvantages as mini-invasion,convenience of operative procedure and fastpostoperative recovery.Intra-operative localization is accurate after combing withCT, stereotaxis or neuro-navigation,thus precising operation,degrading complicationsand getting high total resection rate.4 Though keyhole approaches harboring the quality of mini-invasion,cosmetologiesand fast recorvery, treatment of intracranial aneurysm with this methods have therisks of aneurysm leaky and even disruption,which shuoldn't be ignored.Keyholebone window will become evident limitated factor in case of occluding aneurysmmulti-angularly or controlling bleeding.In condition of aneurysm disruption duringoperation,uncorrect treatment may induce disastrous results.5 Under the overall principle of mini-invasion,selecting optimal mini-invasiveoperation means according to different types of bleeding and hematoma is critical tothe prognosis of patients with hypertensive intracerebral hemorrhage.