Magnetic resonance spectroscopy and the Loewenstein assessment for evaluating cognition after a stroke

Abstract

Objective To explore the cognitive impairment of stroke survivors using magnetic resonance spectra (MRS) and the Loewenstein occupational therapy cognitive assessment (LOTCA), and to analyze their correlation and their clinical significance. Methods Thirty stroke survivors diagnosed with cognitive impairment using the mini-mental state examination formed a cognitive impairment group. Another 30 stroke survivors without cognitive impairment served as stroke controls, while a third group of 30 healthy counterparts were the normal controls. All were assessed using magnetic resonance imaging and the LOTCA and the results were correlated. Results The average LOTCA total score and sub-scores of the impaired group were significantly lower than those of the other two groups. The average LOTCA total scores and the orientation and spatial perception, apparent motion and thinking operation sub-scores of the stroke control group were also significantly lower than those of the normal control group, though their average visual perception and motor praxis scores were not. The average levels of N-acetyl aspartate and creatine (NAA and Cr) in the bilateral hippocampus of the cognitively impaired group were significantly lower than among the controls, while their choline and creatine (Cho/Cr) levels were significantly higher. The average NAA/Cr and Cho/Cr levels in the bilateral hippocampus of the stroke control group were similarly significantly lower and higher than among the healthy controls. The average NAA/Cr levels in the left and right hippocampus were weakly to moderately correlated with the total LOTCA scores and the LOTCA sub-score for attention (r=0.376-0.661 and r=0.396-0.691 respectively). The average value of Cho/Cr in the left hippocampus showed weak to moderate negative correlation with the LOTCA total scores (r=-0.368-0.619), but not with the attention scores. The value of Cho/Cr in the right hippocampus had weak to moderate negative correlation with the LOTCA total score and with the orientation, visual perception, visuo-motor organization and thinking operations sub-scores (r=-0.391-0.632), but no obvious correlation with the scores for spatial perception, motor praxis or attention. Conclusion MRS can be used to assess the cognitive impairment of stroke survivors. MRS and LOTCA scores are closely correlated. MRS combined with LOTCA can evaluate cognitive dysfunction more comprehensively and objectively. Key words: Stroke; Cognitive impairment; Magnetic resonance spectra; Loewenstein occupational therapy cognitive assessment