Longitudinal study of carbon monoxide intoxication by diffusion tensor imaging with neuropsychiatric correlation

Abstract

Background: White matter damage is common after carbon monoxide (CO) intoxication, but in vivo follow-up studies about the mechanism of white matter damage are not possible in pathology series. Diffusion tensor imaging (DTI) and voxel-based morphometry (VBM) can quantify diffusion parameters and volumetric changes in white matter that can be correlated with neuropsychological performances in longitudinal studies.

Methods: We examined 9 patients with CO intoxication using DTI, VBM and neuropsychologic tests at an average of 3 and 10 months after CO exposure. We used data from 18 age- and sex-matched controls for comparison.

Results: We found that cognitive recovery at 10 months after CO intoxication was not significant, although it was after 3 months. The neuropsychologic tests correlated better for the fibre tract of the semicentrum ovale and not the periventricular fibres. Diffusion measures suggest increases in fractional anisotropy, mean diffusivity and axial eigenvalues over time, while increases in radial eigenvalue were evident at 3 months compared with controls. Periventricular white matter atrophy was observed 10 months after CO intoxication.

Limitations: Our study included few cases, and the interpretation of the putative changes on neuroimaging findings cannot be confirmed by histology.

Conclusion: Our study showed that the evolution of white matter injury in CO encephalopathy occurred over time. Cognitive recovery was not evident in the follow-up period because of white matter injuries.

Fig. 1

Clusters with significant differences (red) between the carbon monoxide group 3 months after exposure and controls. The clusters were overlaid on the mean fractional anisotropy skeleton map (green) (all p < 0.05, multiple correction at the cluster level). The background anatomic reference was the Montreal Neurological Institute 152 Image.

Fig. 2

Clusters with significant differences (red) between the carbon monoxide group 10 months after exposure and controls. The clusters were overlaid on the mean fractional anisotropy skeleton map (green) (all p < 0.05, multiple correction at the cluster level). The background anatomic reference was the Montreal Neurological Institute 152 Image.

Fig. 3

Clusters with significant differences (red) between the 3- and 10-month follow-up images in the carbon monoxide groups overlaid on the mean fractional anisotropy skeleton map (green) (all p < 0.05, multiple correction at the cluster level). The background anatomic reference was the Montreal Neurological Institute 152 Image.

Fig. 4

Bar graph showing eigenvalues extracted from the significant regions between the 3- and 10-month follow-up images in the carbon monoxide (CO) group. (A) Axial eigenvalues in CO group show significant differences in the 6 regions (p < 0.05) between 3 and 10 months. (B) Values in radial eigenvalues were not different between 3 and 10 months in the CO group. Axial and radial eigenvalues are expressed in 103 mm²/s. Data are means and standard deviations. T-P = temporoparietal.

Fig. 5

Atrophy of white matter in carbon monoxide–intoxicated patients 10 months after exposure compared with controls by use of voxel-based morphometry. The anatomic reference was the white matter template specific to this study.