Surgical Treatment Of Brainstem Cavernous Malformations: Utility And Predictive Value Of Preoperative Diffusion Tensor Imaging

Background:Brainstem cavernous vascular malformations account for 4%-35% of cerebral cavernous malformations.With the high rate of postoperative disability and mortality,the operation is challenging due to the deep anatomical location of brainstem and dense distribution of important nerve conduction bundle.Magnetic resonance diffusion tensor imaging and diffusion tensor tractography can be used to estimate the structure and position of corticospinal tract before surgery,so as to evaluate the corticospinal tract injury and postoperative motor function of brainstem cavernous malformations.Objective:The purpose of this study was to investigate the application and clinical value of diffusion tensor imaging and diffusion tensor tractography in the operation of brainstem cavernous malformations.Methods:The Clinical data and imaging data of patients with brainstem cavernous malformations treated by surgery in our department from January 2016 to January 2020 were retrospectively collected.Preoperative All patients completed the diffusion tensor imaging and reconstructed the diffusion tensor tractography preoperatively,and the corticospinal tract was divided into the following four categories: 1.normal;2.deviated;3.deformed;4.Interrupted.Fractional anisotropy(FA)and FA values of the regions of interest to the lesion in the brainstem are calculated to obtain the FA ratio(rFA)and FAasymmetry(FAasy).The modified Rankin Scale,BI Score and FMA(Fugl-Meyer motor assessment)scores of each patient at the end of 7 days to at least 3 months after operation were evaluated respectively.By observing the changes of the scores of different patients at different stages after operation,the relationship between the preoperative corticospinal tract and the FA value of the lesions and the scores of patients with brainstem cavernous malformation at the end of 7 days and at last followup after operation were analyzed.The FMA score of the group with good prognosis of motor function was 85-100,and poor prognosis of motor function was 0-84;the modified Rankin Scale(MRS)of the group with good prognosis was 0-2,and the group with poor prognosis was 3-6.Results:The focus was located in 27 cases of pons,7 cases of medulla oblongata and7 cases of midbrain for forty-one patients with brainstem cavernous malformations.According to the statistics of Dammann’s typing and the motor function of the patients7 days after surgery,the prognosis of motor function in the large lesion group was better than that in the small lesion group(p=0.047),and according to the statistics of motor function in the last follow-up,the prognosis of motor function in the large lesion group was better,p=0.014.The reconstructed images of corticospinal tract were clear,including 9 cases with normal morphology,13 cases with deviation,17 cases with deformation and 2 cases with interruption.The correlation between fiber bundle morphology and prognosis of brainstem cavernous malformation was analyzed,P <0.05.In terms of motor function prognosis 7 days after surgery,the group with good corticospinal tract morphology had better motor function prognosis,p=0.020.In the statistics of motor function prognosis in the last follow-up,the prognosis of motor function in the group with good corticospinal tract morphology was better than that in the group with bad corticospinal tract morphology,p=0.018.The average FA value of ROI was 0.314±0.646 on the same side of the lesion,and the average FA value in the contralateral ROI region was 0.450±0.757.In addition,the FA value of CST fiber bundle in the focus side was lower than that in the corresponding side(P < 0.05).By calculation,the rFA average was 0.711±0.151,and the FAasy average was 0.178±0.110. The rFA and FAasy were correlated with the MRS,FMA and BI score at 7 days and the last follow-up respectively(P < 0.02).FA ≥ 0.268 can be regarded as the imaging index of prognosis of BSCM,P < 0.05.Conclusion:The FA value of DTI at the lesion area on the affected side was correlated with the prognosis of patients with brainstem cavernous malformation before surgery.Patients with the FA value of the lesion area on the ipsilesional side ≥0.268 might have a better prognosis.Preoperative DTI can be used to predict the postoperative outcome of patients with brainstem cavernous malformation.