Volumetric MRI and 1H MRS study of hippocampus in unilateral MCAO patients: relationship between hippocampal secondary damage and cognitive disorder following stroke.

OBJECTIVE: To determine whether hippocampi alter in patients at the recovery stage of middle cerebral artery occlusion (MCAO) and whether the changes of hippocampi involve in the cognitive impairment in such patients.
MATERIALS AND METHODS: [corrected] Forty-four patients with unilateral infarction solely in MCAO territory and 44 age-, sex- and education background-matched healthy volunteers were enrolled in this study. All subjects underwent 3-dimensional fast spoiled gradient-echo (3D FSPGR) and sing-voxel proton magnetic resonance spectroscopy ((1)H MRS) protocols at a 1.5 T MR scanner. The ratios of n-acetylaspartate/creatine (NAA/Cr) and myo-inositol/creatine (mI/Cr) were obtained by using software integrated in the MR scanner. The hippocampal volumes were estimated by manually measurement.
RESULTS: The volume and NAA/Cr ratio were found significantly decreased and mI/Cr ratio significantly increased in the hippocampus ipsilateral to occluded middle cerebral artery (MCA) as compared with values in the contralateral hippocampus or healthy control. A reduced NAA/Cr ratio was also observed in contralateral hippocampus compared to controls. The shrinkage ratio of hippocampus ipsilateral to MCAO was found related to the Mini-Mental State Examination (MMSE) score.
CONCLUSION: Our study identified that the hippocampal secondary damage occurred in patients after MCAO, and it could be evaluated noninvasively by volumetric magnetic resonance imaging (MRI) and (1)H MRS. Moreover, the hippocampal secondary damage in MCAO patients indeed contributed to their cognitive impairment.