Intraoperative Brain Shift In The Supertentorial Surgery With Neuronavigation System: A Report Of 15 Cases

BACKGROUDNeuronavigation surgery is an imaging- guide neurosurgery that had developed fast last decade, and it was introduced to our country for these years. Neuronavigation system can combine the digital neuroimaging and actuality anatomy structure real-time, taking an importance effect in designing Operative incision, optimization of operative approach, intraoperative locating the lesion fidelity and definite the extent of eixcision. But the system also has unconquerable limitation at present: intraoperative brain shift which causing decrease of accuracy of the system, and decrease of reliability of the neuronavigation surgery.Lately the studies of brain shift intraoperation of neuronavigation surgery focus on the assessment of parameter that causing brain shift, measure of intraoperation brain shift, update of preoperation imaging, and because of the development of computer science, the mathematical model had been developed. For the application of intraoperative MRI and intraoperative ultrasound and combining with computer mathematical model, intraoperative updating of imaging will come true in the future, helping the surgeon to be given the real-time of imaging, fidelitily definite the extent of excision andminimize the injury of brain, compensate the intraoperative brain shift.Roberts etc. study had provided data about the brain shift and brain deformation, and the difference between superficial and deep brain shift. Lately study about brain shift in neuronavigation surgery focus on the application of intraoperative MRI and intraoperative ultrasound, but lack initial data of brain shift, which helping to analyse the preoperation imaging parameters for judging the brain shift. And there are measuring brain shift only for one time in a given patient, lacking real-time data that gather in difference time in the operation.OBJECTIVEOur study analyses the effects of several pre-operative imaging parameters for the brain shift, to verify the predictive value of the tumor volume, distance of lesion and cortex, pre-operative cerebral edema, midline shift for the brain shift, to confirm the correlation between the cortex and subcortex brain shift.MATERIALS AND METHODSOur study retrospective analyses 15 patients, the patients come from the Sir Run Run Hospital of Zhejiang University Medical college, all patient received neuronavigation system assist operation of supra-tentorial lesion. And they received pre-operative MRI scan, all the pre-operative and intra-operative imaging had preserved in the computer hard disc of neuronavigation system. We recall these imaging and measure the nature of lesion, the volume of lesion, the location of lesion, the midline shift, the pre-operative brain edema etc. We measure the brain shift through the intra-operative record. SPSSsoftware was used for the statistical analysis.RESULTFor the entire patients, a contrast was make between the cortical brain shift and the subcortical brain shift, the cortical brain shift was: -7.1 ~ 10.5mm[mean: 4.3mm, standard deviation: 3.5mm], the subcortical brain shift was: -5.54~6.5mm[mean: 2.84mm, standard deviation: 2.4mm]. Statistical analyses findings: there is significant positive correlation between the cortical brain shift and the subcortical brain shift, and in all patients the cortical brain shift is greater than the subcortical brain shift. Significant correlation was found between intra-operative brain shift and the lesion volume (r=0.45) , midline shift(r=0.30), the size of the craniotomy(r=0.40). Discriminant analysis was made between intra-operative brain shift and the pre-operative imaging parameter, the lesion volume had the most predictive value for intra-operative brain shift in the supertentorial surgery with neuronavigation system.CONCLUSIONS1. The volume of lesion in pre-operative imaging is the most important predictive parameter for the intra-operative brain shift, intra-operative brain shift positive correlation with the volume of lesion> midline shift and the size of the craniotomy02. The cortical and subcortical brain shift have highly significant positive correlation, cortical brain shift is greater than subcortical brain shift.