Altered Sleep Spindles in Delayed Encephalopathy after Acute Carbon Monoxide Poisoning

Two similar carbon monoxide poisoning cases with different outcomes: evidence from longitudinal fMRI

Prognosis after carbon monoxide (CO) poisoning is difficult to assess using structural images. Functional connectivity provided by functional magnetic resonance imaging (fMRI) may explain the mechanism of differential prognosis. We report here two cases of carbon monoxide poisoning with simultaneous coma. They were nearly normal on days 7-8, but diagnosed with delayed neurological sequelae (DNS) with cognitive and motor impairments on days 22-29. Similar Methylprednisolone pulse therapy and hyperbaric oxygen therapy were given to them. The movement disorder of case 1 improved slightly during the recovery stage, while the movement disorder of case 2 worsened significantly. In case 1, the function of supplementary motor area decreased first and then increased, and the function of pallidum increased first and then decreased. Case 2 showed a reduction in the supplementary motor area and small changes in the pallidum after DNS, but both were reduced during recovery stage. The cognitive ability of case 1 remained poor, while that of case 2 improved during the recovery stage. FMRI showed damage to the right and bilateral hippocampus in case 1 and partial damage to the left hippocampus in case 2. Taken together, fMRI can be a useful method to study functional connectivity abnormalities corresponding to different prognoses.

Altered regional homogeneity in delayed encephalopathy after carbon monoxide poisoning: A resting-state fMRI study

OBJECTIVE

To investigate alternations in spontaneous brain activities reflected by regional homogeneity (ReHo) in patients with delayed encephalopathy after acute carbon monoxide poisoning (DEACMP) using resting-state functional magnetic resonance imaging (rs-fMRI).

METHODS

Twenty-one patients with DEACMP and 21 age, sex and education matched healthy controls (HCs) received rs-fMRI scanning and clinical assessment. We used the ReHo method to analyze the interregional synchronized activity of all participants. Two sample t-tests were performed to compare the ReHo maps between the two groups. Pearson correlation analysis was then used to assess the correlations between clinical measures and abnormal ReHo in DEACMP patients.

RESULTS

Compared with HCs, DEACMP patients showed significantly decreased ReHo in bilateral cerebellum posterior lobe, pons, bilateral basal ganglia, while increased in the posterior cingulate, calcarine, bilateral occipital lobe(GRF correction, voxel P value <0.001, cluster P value <0.05). Negative correlation was found between Mini-mental State Examination (MMSE) scores and the ReHo values of posterior cingulate gyrus (r = -0.672, p < 0.05) in the DEACMP group, while positively related to the time from CO poisoning to MRI scan (r = 0.428, p < 0.05).

CONCLUSION

Patients with DEACMP exhibited altered ReHo in the multiple functional brain regions, which provide evidence for local brain dysfunctions and may help to understand the neuropathologic mechanism for the disease.

Abnormal degree centrality in delayed encephalopathy after carbon monoxide poisoning: a resting-state fMRI study

Purpose

To explore neuropathologic mechanisms in functional brain regions in patients with delayed encephalopathy after carbon monoxide poisoning (DEACMP) from the perspective of the brain network nodes by resting-state functional magnetic resonance imaging (rs-fMRI).

Methods

The fMRI and cognitive assessments were performed in 25 patients with DEACMP and 25 age-, sex- and education-matched healthy controls (HCs). Data analysis was performed via the degree centrality (DC) method. Then, the associations between the cognitive assessments and DC in the identified abnormal brain regions were assessed by using a correlation analysis.

Results

Compared with the HCs, the DEACMP patients displayed significantly decreased DC values in the right superior frontal gyrus, right precentral gyrus, right angular gyrus, right marginal gyrus, right hippocampus, and left thalamus but increased DC values in the right inferior frontal gyrus, right cingulate gyrus, left superior temporal gyrus, left medial temporal gyrus, right lingual gyrus, and right posterior cerebellar lobe, pons, and midbrain (GRF correction, voxel P value < 0.001, cluster P value < 0.01). The correlation analysis in the DEACMP group revealed that there was a negative correlation between the DC values in the right hippocampus and MMSE scores, whereas a positive correlation was observed in the right cingulate gyrus.

Conclusions

Patients with DEACMP exhibited abnormal degree centrality in the brain network. This finding may provide a new approach for examining the neuropathologic mechanisms underlying DEACMP.