The Secondary Degeneration Of The Thalamic Radiation Fibers After Thalamic Hemorrhage Detected With Diffusion Tensor Imaging

Background: Cerebral hemorrhage accounted for20%to30%of all strokein China. It has the highest death rate of acute cerebrovascular disease. Suchpatients are generally poor prognosis, given a heavy burden on society and thefamily. So, how to prevent the occurrence of cerebral hemorrhage and improvethe prognosis of patients with cerebral hemorrhage is the primary clinicalproblem. Currently, for the treatment of cerebral hemorrhage, it always focusedon hemorrhage lesion and its peripheral tissues, while secondary damage of thedistant parts linked to hemorrhage focal through nerves was little attention.There are many studies have shown that secondary damage would hinderrecovery of neurological function after cerebral hemorrhage. Therefore, toexplore the characteristics of occurrence and development of secondary damage is important for promoting the recovery of neurological function. Early imagingmethods for detecting secondary damage after central nervous system injurywere primarily computer tomography(CT) and conventional magnetic resonanceimaging (MRI), but detection rate of secondary damage by the two methods isvery low. Diffusion tensor imaging(DTI) open the door to the research onsecondary damage. It is a microscopic imaging method base on tracking themovement of water molecules diffusion of anisotropy to reflect organizationalstructure. Compared with CT and MRI, it can be more sensitive to detectsecondary damage, and also capable of quantifying the extent of secondarydamage by DTI parameters. It allows researchers to observe the development ofsecondary damage directly. Recent studies about DTI showed that secondarydamage would occurs after cerebral hemorrhage and was progressive over time.It may hinder recovery of neurological function. A lot of intracranial nerve fibersexchange neurons in the thalamus. Secondary damage of the distant parts linkedto focal through nerves would occur following the thalamus hemorrhage. To thebest of our knowledge, no DTI data on secondary damage in the early subacutestage after thalamus hemorrhage at sites of thalamic radiation fibers from theinitial hemorrhage is available. The purpose of this study is to evaluate whetherDTI can detect changes of water diffusion that are reflective of early secondarydamage in the thalamic radiation fibers within the first week after thalamushemorrhage, and to test whether DTI findings of early secondary damagecorrelate with measures of sensation deficit and outcome.Objective: The purpose of this study is to evaluate whether DTI can detectchanges of water diffusion that are reflective of early secondary damage in thethalamic radiation fibers within the first week after thalamus hemorrhage, and totest whether DTI findings of early secondary damage correlate with measures of sensation deficit and outcome.Methods: Eleven consecutive patients with thalamus hemorrhagehospitalized in the neurology department at the First Affiliated Hospital ofGuangXi Medical University from June2012to January2014were included inthe experiment group. Inclusion criteria were as follows:1）Age range from18to65years;2)initial attack within the first week after thalamus hemorrhage;3)Moderate to severe sensation deficit and no disturbance of consciousness onadmission;4)unilateral thalamus hemorrhage should be confirmed byconventional MRI and SWI without any abnormal signals in other regions.Patients with a history of the central nervous system diseases such as cerebralhemorrhage, cerebral infarction, multiple sclerosis, encephalitis etc or patientswith hemorrhage recurrence or other central nervous system diseases occurrenceduring follow-up period were excluded. Eleven healthy volunteers matched withthe experiment group in gender and age were used as the control group. Patientsunderwent DTI in the first week, volunteers also proceeded one time DTI. Allpatients were evaluated with the National Institutes of Health StrokeScale(NIHSS) and the sensory disturbance rating(SDR) to assess the loss ofneuron function and sensation in the first week, forth week and the twelfth weekafter onset. All the data were unitively analyzed after this experiment. Theregions of interest equivalent with4Voxels was symmetrically placed on axialslices in bilateral thalamus and centrum semiovale and mean diffusivity(MD)and fractional anisotropy(FA) were separately measured. All values arepresented as mean±SD. For the control group，both sides were averaged forgroup comparison with t test. Experimental group at each time of clinicalneurological score using repeated measures analysis of variance, and betweentwo groups at different time points were compared using analysis of variance SNK. Spearman rank correlations were calculated between DTI parameters andthe absolute value of percent change of clinical scores.Results: In both cases, signal changes within the lesion are typical for acuteto subacute hemorrhage lesions with significantly reduced MD and reduced FA.FA was markedly reduced in the centrum semiovale of the affected side relativeto the contralateral side and control groups (0.45±0.06vs0.52±0.04,0.54±0.05, P <0.05).MD showed no significant difference among both side andcontrols（0.69±0.06vs0.72±0.03、0.70±0.04（*10-3），P＞0.05）. NIHSS scoreand section8of NIHSS score for feeling(NIHSS8)gradually decreased over thetime period from W1to W12(P <0.05), but SDR gradually increased (P <0.05),the mRS score of the12th week was1.78±1.12. There was no significantcorrelation between FA values, MD values in the lesions and the percent changesin clinical scores. FA values in the centrum semiovale of the affected side werenegatively correlated with percent changes in the SDR(r=-0.56, P <0.05) butwere not significantly correlated with NIHSS and NIHSS8.MD values were notcorrelated with the percent changes in clinical scores.Conclusion: Thalamic hemorrhage can lead to secondary damage of thethalamic radiation fibers. DTI can detect this early changes in the thalamicradiation fibers after thalamus hemorrhage, but also quantize the extent ofdamage in the form of data accurately. Secondary damage of the thalamicradiation fibers may hinder recovery of neurological function.