Callosal damage and cognitive deficits in chronic carbon monoxide intoxication: A diffusion tensor imaging study

Purpose To evaluate the correlation between microstructural damage in the corpus callosum (CC) and the cognitive performance of patients with or without delayed encephalopathy (DE) after carbon monoxide (CO) intoxication in the chronic stage. Methods Diffusion tensor imaging (DTI) was performed more than 6 months after CO intoxication for 10 patients with DE and 10 patients without DE recruited from out-patient clinics, as well as for 15 normal controls (NCs). Using a probabilistic tractography method to parcel the CC based on fiber projections to cortical connectivity patterns, the DTI indices were calculated in the CC subregions and further correlated with cognitive performance. Results The DE group exhibited significantly lower fractional anisotropy (FA) and higher radial diffusivity (RD) values in the prefrontal, premotor, primary motor, primary sensory, parietal, and occipital CC subregions than did the NCs. The DE group also exhibited significantly lower FA values in the prefrontal and premotor subregions than did the non-DE group. Lower FA and higher RD values in the CC subregions were associated with poorer scores on the symbol search test. Conclusions CO intoxication may cause lower FA and higher RD in the CC subregions, with subsequent cognitive impairment. This finding suggests that selective CC damage after CO intoxication is more profound in patients with DE.