Retrospective Analysis For The 50 Cases Of Brain Stem Tumor Treated And Microsurgery

Objective: The organic structure and anatomic relationship ofbrain stem is very complex, which caused many deficiencies of brainstem like poor tolerance to injury, limited space for operation, highrisk for operation and high mortality rate after operation. So it is agreat challenge for neurosurgery doctor to improve the surgicaloperation achievement ratio of brain stem tumor and achieve bettereffect after treatment. The dissertation aims to analyze the factorseffected the operation achievement ratio in the aspect of clinicalmanifestation, imageology, pathological types, surgical indication,electrophysiology monitoring, the period surround operation andoperation method via summarizing 50 cases and data of brain stemtumor operating treatment from year 2000 to 2005 in the departmentof Neurosurgery in the 1st Hospital of Jilin University. Operation method: These 50 cases were treated through themicrurgy methord. Depending on the MRI or MRA. Examinationresults, the operation approach must avoid the important nucleus. atthe same time it must be the nearest way from the brain stem surfaceto the tumor, using the Kyoshima's safety regions as far as possible:they are upper-cranial nerve trigone (among fasciculus longitudinalismedialis, cranial nerve and cerebellar peduncle), and under-cranialnerve trigone (among fasciculus longitudinalis medialis, striaemedullares and cranial nerve);Hakuba discovered two positions thatcan be incised safely: the position between quadrigeminal bodies andcranial nerve can be incised transversal;the position under brachiumof inferior colliculus, between the cerebral peduncle andquadrigeminal bodies canbe incised perpendicular.The incisedcircumscriptions of these districts mentioned above should be limitunder 1cm. general all purpose operation approach are: 1. post-mesoapproach: refer to the tumors locate in inferior segment of pons anddorsi-medulla oblongata. 2. hypopulvinar-supratentorium approach: itis the orthodox Poppen approach, refer to the tumors locate indorsi-deutocerebrum and superior segment of pons. 3. hypotemplepulvinar approach: refer to the tumors locate in upper deutocerebrumand pons. 4. lateral cleft approach: refer to the tumors locate ingaster-deutocerebrum. 5. post mastoid process approach: refer to thetumors locate in anterior aspect pons and medulla oblongata.Result: 37 cases were whole excised, 9 cases were partly ormostly excised under microscope, 4 cases which can not be excisedmainly adopted the stereotactic radiotherapy depending on thepathology after operation. 3 cases died of respiratory failure, two ofwhich give up therapy and died after leaving hospital. 1 case died ofrenal failure. The curative effect of the rest is satisfied. 38 cases'neural function has become better, 4 cases did not improve comparedwith the situation before operation, and 4 cases become aggravation.Conclusion: The objective of operation is to excised the tumor asmuch as possible on the premise of keeping neural function thus torelease its pressure to the brain stem, get through the Cerebrospinalfluid circulation iter, abate the intracranial hypertension, keep thenormal neural function and offer better condition to the radiotherapy.(1) The whole and accurate examination, diagnoses, andtreatment are the basis for the success of operation. Fully acquired theoperation indicatio would contribute to the reduction of complicationand mortality rate of the operation. Zhou liangfu. etc think that ifneural function obstacle of brain stem tumor go on developing, itshould be adopted to the surgical treatment. These situations areappropriate to surgical treatment as generally thinking. 1. ectogenesistumor, the principal part of the tumor protrude toward to the fourthventricle, one side of cerebellopontine angle, cisterna magna orintra-cerebellar hemisphere with clear boundary. 2. nonectogenesistumor, the focus locate on the superficial position of brain stem and islimited. 3. endogeny tumor, the tumor locate inside brain stem, there iscystis degeneration or hemorrhage and necrosis focus in the tumorbody 4. cervical-myelencephalon tumor, the tumors grow diffusely butthe focus is clear in certain position. The operation approach can bechosen depending on the growth position, the growth orientation, andblood supply situation of tumors.(2) For different peculiarity brain stem tumors should adoptdifferent operation methods. Astroglioma: there are always no clearcircumscription between astroglioma and brain stem, it is difficult tototally ectomize the tumor, so the operation should be inside tumors,just ectomize the bulk part to sufficient decompression, and use theradiotherapy, chemotherapy and isotope treatment for addition.Ependymocytoma: always have the clear circumscription, grows tofourth ventricle, cerebellopontine angle and cisterna magna, can betotally isolated and ectomized. The resection of parenchymatous brainstem angioreticuloma should to follow such principle: first to deal thesupply arteries, second to liberate the tumor, then cut off the drainageveins, and embolism the tumor vessel to limited blood supply 1 or 2days before operation if needed. Angiocavernoma: first should resortshematocele to obtain enough spaces to totally resect the paries ofhaematoma. If focus of infection wasn't resect completely, should usefulgerize the focus to prevent rehaemorrhagia.(3) Using BAEP and SLSEP to control during operation canprovide the information of brain stem function to surgical doctorinstantly. If the pathological changes of brain stem involve in theaudition conduction iter, BAEP will relatively change;if they involvein the upward medial lemniscus conduction iter, then SLSEP willrelatively change. In the period of dragging, separating the boundaryof tumor and excising the tumors during the operation, the BAEPand/or SLSEP of patient will relatively change, so using the controlduring the operation can instruct the orientation of operation and theboundary of tumor for excising, reduce or avoid the injury of brainstem function and provide objective guideline for prognosticating theprognosis.(4) Treatment in the period surrounds operation: Generally, thepatient has the syndrome of waterhead which is complicated by thebrain stem tumor before operation and the normal complications afteroperation are respiratory disturbance, dysphagia, and alimentary tracthemorrhage. etc. The doctor will use the ventriculo-peritoneal shuntdepending on the detailed situation before operation;embolize theblood vessel which supported the tumor;and give the patients HighProtein Liquid Diet and fluid replacement to improve their toleranceto the operation, and give continuing oxygen supply, tracheotomypromptly nasogastric feeding and use breathing machine to ventilatorysupport when necessary. Doing the treatment like medication,transfusion and gastrointestinal decompression instantly andaccurately would improve the operation achievement ratio.(5) Other treatment method: The chemotherapy of brain stemtumor can not be confirmed so far;the radiotherapy of brain stemtumor has affirmative effect but the livability rate is only 20-30%within 5 years. The stereotactic radiotherapy has the potentialpossibility in improving the local control rate of tumors and becauseof its particular merit like small trauma, less complication, saving timeand better effect, it will likely to be the assistant or substitutabletreatment method expected the micrurgy. However, the clinical data ofstereotactic radiotherapy to brain stem tumor is limited and this needsto father accumulate and summarize.