[Research progress on head imaging features of carbon monoxide poisoning and delayed encephalopathy]

Acute carbon monoxide poisoning and its delayed encephalopathy have obvious damage to the central nervous system. There are different neuroimaging changes in different stages of the disease, and they are relatively specific. This article reviews the clinical research progress on the imaging changes of carbon monoxide poisoning and delayed encephalopathy, including computed tomography (CT) , conventional magnetic resonance imaging (MRI) , diffusion weighted imaging (DWI) , diffusion tensor imaging (DTI) , diffusion kurtosis imaging (DKI) , magnetic resonance spectroscopy (MRS) and other imaging changes reflecting the function and metabolic state of the brain tissue.

Investigation of the relationship between MBP gene polymorphisms and delayed encephalopathy after acute carbon monoxide poisoning

Increasing evidence reveals that delayed encephalopathy after acute carbon monoxide poisoning (DEACMP) results from the combined effects of environmental and genetic factors. The main pathological feature of DEACMP was generalized demyelination of cerebral white matter. Myelin basic protein (MBP) levels in cerebrospinal fluid (CSF) and serum samples from DEACMP patients were elevated. This study investigated the association of MBP single nucleotide polymorphisms(SNPs) (rs470555, rs470724, rs4890785, rs595997, rs76452994, and rs921336) with DEACMP. We genotyped 416 DEACMP patients and 785 age, educational level, and sex-matched ACMP patients for rs470555, rs470724, rs4890785, rs595997, rs76452994, and rs921336 SNPs using the Agena MassArray. There were no significant differences in the allele frequency distribution, four genetic models, and genotype distributions between the DEACMP and ACMP groups for rs470555, rs470724, rs4890785, and rs595997. However, significant differences were observed for rs76452994 and rs921336. This study revealed that the MBP polymorphisms, rs470555, rs470724, rs4890785, and rs595997, were not associated with DEACMP. Based on the codominant, dominant, and overdominant genetic inheritability patterns, the MBP rs76452994 and rs921366 polymorphisms were associated with DEACMP. Furthermore, the G allele of rs76452994 and T allele of rs921336 could lead to higher DEACMP risk.

[A suspected case of delayed encephalopathy after acute hydrogen sulfide poisoning]

The main component of the gas in the fish storage tank is hydrogen sulfide. Hydrogen sulfide poisoning is a common occupational chemical poisoning among fishermen in summer, and acute hydrogen sulfide poisoning can manifest as toxic encephalopathy. This paper analyzes a patient with delayed encephalopathy suspected of acute hydrogen sulfide poisoning. The patient was unconscious for 18 days after waking up for 5 days after acute hydrogen sulfide poisoning. After waking up again, there were symptoms such as decreased limb muscle strength, ataxia, swallowing, dysarthria, and the clinical characteristics were significantly different from those of delayed encephalopathy caused by acute carbon monoxide poisoning, such as decreased cognitive function and damage to extrapyramidal system.

[Research progress on the mechanisms of delayed encephalopathy in acute carbon monoxide poisoning]

In our country, there are a large number of carbon monoxide poisoning patients every winter. 10% to 30% of patients with acute carbon monoxide poisoning develop acute carbon monoxide poisoning delayed encephalopathy after a "false recovery period" of about 2 to 60 days. The morbidity and mortality rates of the disease are extremely high, but there is still no effective treatment for this condition. The pathogenesis of the disease is complex, and there is no clear conclusion yet. After consulting a large number of recent relevant literatures, this article reviews the main research results of the pathogenesis of the disease so far, with an aim to facilitate its early clinical diagnosis and correct treatment.

[The predictive value of low T3 syndrome for delayed encephalopathy caused by severe acute carbon monoxide poisoning]

Objective: To explore the predictive value of low T3 syndrome (LT3S) for patients with delayed encephalopathy after acute carbon monoxide poisoning (DEACMP) . Methods: In May 2020, 137 severe acute carben monoxide poisoning (SACMP) patients were selected from Harrison International Peace Hospital Affiliated to Hebei Medical University from January 2019 to January 2020 as subjects. Blood samples were taken after admission to test thyroid function. Followed up for 60 d, the patients were divided into DEACMP group (45 cases) and non DEACMP group (92 cases) according to their prognosis. Clinical data of patients in two groups were collected and compared. The Cox regression with multiple independent variables was used to analyze the independent risk factors of DEACMP. Pearson correlation analysis was used to evaluate the correlation between totall triiodochyronine (TT3) level and Acute Physiology and Chronic Health Evaluation (APACHE) Ⅱ score. The receiver operating characteristic (ROC) curve of TT3 and APACHE Ⅱ scores for predicting DEACMP were drawn. Results: Compared with non DEACMP group, the age, APACHE II score, LT3S rate and diabetes prevalence in DEACMP group were higher, and the Glasgow coma scale (GCS) score was lower (P<0.05) . Cox regression analysis showed that age, APACHEⅡ score and LT3S were independent risk factors of DEACMP in patients with SACMP (OR=1.040, 95%CI:1.005-1.077; OR=1.070, 95%CI: 1.002-1.143; OR=4.210, 95%CI: 1.707-10.379; P<0.05) . Pearson correlation analysis showed that TT3 level was negatively correlated with APACHE Ⅱ score (r=-0.397, P=0.000) . ROC curve showed that the cut-off value of TT3 level for DEACMP prediction was 1.078 nmol/L, the area under curve (AUC) was 0.755, the sensitivity was 82.6%, and the specificity was 73.3%. The cut-off value of the APACHE Ⅱ score for predicting DEACMP was 16, and the AUC was 0.725, sensitivity was 93.3%, and specificity was 60.9%. Conclusion: This study showed that LT3S minght be an independent predictor of DEACMP in patients with SACMP. Thyroid function is closely related to the severity of SACMP patients.

[A clinical and pathological report of delayed encephalopathy after heat stroke]

Objective: To explore the clinical manifestations, dynamic neuroimaging changes and brain histopathologic characteristics of a patient with delayed encephalopathy after heat stroke. Methods: In October 2019, the clinical manifestations, electroencephalogram, cerebrospinal fluid, imaging changes and brain histopathological characteristics of a patient with brain damage caused by heat stroke were retrospectively analyzed. Results: The patient was a 40-year-old male who suddenly appeared dizziness, unconscious, high fever when working in the high temperature environment. The EEG showed diffuse slow wave activity. Early CT was normal, and abnormal signals gradually appeared in the basal ganglia region of the thalamus after a few days. In the late, the MRI found a large area of abnormal signals under the cerebral cortex, and white matter was involved. Pathological examination of brain biopsy showed that cortical neuron loss, loose white matter changes, and significant demyelination changes, while no inflammatory cell infiltration was observed in subarachnoid space, meninges, and dermal white matter. Conclusion: Imaging examination dynamic changes of the delayed encephalopathy is important in the heat stroke, and the main pathological manifestation is demyelination.

[Correlation between early eeg dual-frequency index monitoring combined with lactic acid clearance rate and delayed encephalopathy with acute severe carbon monoxide poisoning]

Objective: To analyze the correlation and predictive value between early BIS monitoring combined with lactic acid resolution (LCR) and delayed encephalopathy with acute severe carbon monoxide poisoning (ASCMP) . Methods: Select 96 cases of our hospital ASCMP patients were analyzed retrospectively in March 2020, and follow-up of 60 days, according to the outcome in patients with acute carbon monoxide poisoning (DEACMP) delayed encephalopathy group with good prognosis, compare two groups of general information, admission BIS average 24 h and 24 h after treatment the LCR, According to the 24h LCR test results, patients were divided into high LCR group (LCR>15%) and low LCR group (LCR≤15%) , analysis the BIS average, the correlation of the LCR with DEACMP and both individual and joint of DEACMP predictive value, Comparing clinical data of patients with high LCR and low LCR. Results: The mean BIS value of the DEACMP group 24 hours after admission was significantly lower than that of the group with good prognosis (P< 0.05) . LCR of DEACMP group was significantly lower than that of the group with good prognosis after 24 h treatment (P<0.05) . The prevalence of DEACMP in patients with high LCR was significantly lower than that with low LCR (P<0.01) ; In the early stage, BIS mean, LCR and DEACMP were negatively correlated (P< 0.05) , and the area under the curve predicted by BIS mean, LCR and their combination on DEACMP was 0.799, 0.847 and 0.902, respectively. Conclusion: Early BIS monitoring combined with LCR has a significant correlation with DEACMP, and the combined effect of the two is better. Early BIS combined with LCR detection can provide effective guidance for the prognosis assessment of ASCMP patients.

Hyperbaric oxygen therapy mobilized circulating stem cells and improved delayed encephalopathy after acute carbon monoxide poisoning with up-regulation of brain-derived neurotrophic factor

Background Delayed encephalopathy (DE) is the most severe complication after acute carbon monoxide (CO) poisoning, which seriously affects the outcome of patients and leads to a high disability rate. Prior studies have shown that hyperbaric oxygen (HBO₂) therapy is therapeutic for DE due to reducing immune-mediated neuropathology and thus improving cognitive performance. Methods In our present perspective study, five DE patients were treated regularly with HBO₂ therapy. The mini-mental state examination (MMSE) and Barthel index (BI) were intermittently collected during their hospitalization for mental and physical status evaluation, the peripheral bloods were serially sampled to determine the concentration changes of circulating stem cells, as well as corresponding BDNF and neural markers. Results MMSE and BI showed series of improvements after multiple HBO₂ therapies. The CD34⁺/CD90⁺ and CD34⁺/CD133⁺ dual positive cells, which were categorized as circulating stem cells, were observed an overall up-regulation since the beginning of the DE onset upon the application of HBO₂ therapy. Characteristic neurotrophin BDNF, neural markers such as nestin and synaptophysin (SYP) were also up-regulated after exposure of HBO₂. Conclusion The application of HBO₂ therapy is of significance in improving the cognition of DE patients, along with mobilized circulating stem cells. We primarily infer that the CD34⁺/CD90⁺ and CD34⁺/CD133⁺ cells were mobilized by HBO₂ exposure and have played a positive role in cognition improvement on DE patients by up-regulation of BDNF, nestin and SYP. The altering amount of circulating stem cells mobilized in peripheral blood could be a potential marker on predicting the outcome of DE.

[The association study of WWP2 gene polymorphisms with delayed encephalopathy after acute carbon monoxide poisoning]

Objective: To investigate the association of WWP2 single nucleotide polymorphism (rs3790088, rs4247109) with delayed encephalopathy after acute carbon monoxide poisoning (DEACMP) , and explore the influences of DEACMP genetic predisposition. Methods: From November 2006 to December 2017, 235 DEACMP cases and 429 acute carbon monoxide poisoning (ACMP) cases were selected. All ACMP patients were followed up for more than 90 days without DEACMP. The DNA in all blood samples were extracted with the blood Genome DNA Extraction Kit. The method of Sequenom Mass Array SNP technique was used to detect the genotype and allele of WWP2. All DEACMP patients were assessed every 3 days after hospitalization by the Hasegawa Dementia Scale (HDS) and Activity of Daily Living Scale (ADL) . The distribution of genotypes in conformty with Hardy-Weinderg law was analyzed by goodness-of-fit χ(2) test, and χ(2) test was used for association analysis. Results: For rs3790088, there were 226 DEACMP cases and 414 ACMP cases. For rs4247109, there were 234 DEACMP cases and 428 ACMP cases. For rs3790088 and rs4247109 in WWP2 gene: there were not significant differences in the gene genotype distribution and allele frequency of both DEACMP group and ACMP group (P>0.05) . According to gender, there were not significant differences in WWP2 gene genotype distribution and allele frequency between two female groups and two male groups (P>0.05) . After analysis by genetic model, the genotype distributions in both DEACMP group and ACMP group were not significantly differences in three genetic models (codominant genetic model, recessive genetic model and dominant genetic model, P>0.05) . Conclusion: It has not confirmed the genetic correlation between the two gene single nucleotide polymorphisms (rs3790088, rs4247109) of WWP2 gene and the incidence of DEACMP.

[Assessment of efficacy of acupuncture combined with hyperbaric oxygen therapy for patients with delayed encephalopathy of CO intoxication by magnetic resonance voxel incoherent motion imaging]

OBJECTIVE

To observe the effect of acupuncture plus hyperbaric oxygen (HBO) on cerebral blood perfusion in patients with delayed encephalopathy after carbon monoxide poisoning (DEACMP).

METHODS

Twenty-eight patients with DEACMP were randomly divided into acupuncture group (n=14 cases) and control group (n=14 cases). Patients of the acupuncture group were treated by using "Xingnao Kaiqiao" needling technique (specific set of acupuncture points as Yintang ［EX-HN3］, Shangxing ［GV23］, Baihui ［GV20］, Sishenchong ［EX-HN1］, Fengchi ［GB20］, Taichong ［LR3］, etc., and strong stimulation) combined with HBO in an air pressurized tank, and those of the control group treated by simple HBO. The treatment was conducted once a day, 5 days a week for 6 weeks. All the patients underwent head routine magnetic resonance imaging (MRI) and intravoxel incoherent motion imaging(IVIM) scan before and after the treatment. The values of pseudo-diffusion coefficient D (D*) and perfusion fraction (f) of the bilateral semi-oval centers were measured by using MITK software package to calculate the ave-rage fD* value (f×D*). The Barthel index (BI) score was used to assess the patients' daily living ability, and the correlation between parameter values was evaluated by Pearson method.

RESULTS

After the treatment, the values of f, fD* and BI scores were significantly increased in both acupuncture group and control groups (P<0.05). The values of the 3 indexes were significantly higher in the acupuncture group than those in the control group (P<0.05). The values of f and fD* were positively correlated with BI score (P<0.05), with the correlation coefficients being 0.822, 0.636 and 0.601, respectively between the fD* and f, BI and f, and BI and fD*.

CONCLUSION

Acupuncture combined with HBO can significantly improve the low-perfusion of bilate-ral semi-oval center and daily living ability in patients with DEACMP, being significantly superior to simple HBO therapy in the curative effect.

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.

Wallerian degeneration of bilateral cerebral peduncles after acute carbon monoxide poisoning

Background

Cases of Wallerian degeneration of bilateral cerebral peduncles after acute carbon monoxide poisoning have not yet been reported. To date, most of the delayed encephalopathy after acute carbon monoxide poisoning (DEACMP) lesions captured in magnetic resonance imaging (MRI) has been located in the subcortical white matter and basal ganglia. Here we report two cases of DEACMP with abnormalities in the bilateral cerebral peduncles. The etiology of abnormalities, which were strictly confined to the bilateral cerebral peduncles, was Wallerian degeneration secondary to upstream nerve axonal damage, making this the first report on such bilateral cerebral peduncle abnormalities after DEACMP.

Case presentation

In this report, we present two cases of DEACMP with abnormal signals in the bilateral cerebral peduncles captured during brain MRIs. Case 1 was of a 68-year-old man who presented with paroxysmal disturbance of the consciousness, left limb weakness for 16 days, and lagging responses for 2 days. Case 2 was of a 55-year-old man who was unconscious for 6 h. In addition to the above mentioned characteristics on the brain MRIs, the electroencephalography of case 1 indicated that his forehead scans had a mixture of wide sharp, sharp, and three-phase waves. Brain diffusion tensor imaging of case 2 further proved that the bilateral cerebral anomalies represented Wallerian degeneration secondary to upstream axonal damage. After the definitive diagnosis, the patients returned to the local hospital for hyperbaric oxygen therapy.

Conclusions

Wallerian degeneration of the bilateral cerebral peduncles after acute carbon monoxide poisoning has never been reported before. The abnormal signals in the bilateral cerebral peduncles captured during brain MRIs indicated Wallerian degeneration secondary to upstream axonal damage; thus, these two cases may further our understanding of DEACMP imaging.

Carbon monoxide poisoning-induced delayed encephalopathy accompanies decreased microglial cell numbers: Distinctive pathophysiological features from hypoxemia-induced brain damage

Carbon monoxide (CO) causes not only acute fatal poisoning but also may cause a delayed neurologic syndrome called delayed encephalopathy (DE), which occasionally occurs after an interval of several days to several weeks post-exposure. However, the mechanisms of DE have not been fully elucidated. This study aimed to clarify the pathophysiology of CO-induced DE and its distinctive features compared with hypoxemic hypoxia. Rats were randomly assigned to three groups; the air group, the CO group (exposed to CO), and the low O₂ group (exposed to low concentration of O₂). Impairment of memory function was observed only in the CO group. The hippocampus tissues were collected and analyzed for assessment of CO-induced changes and microglial reaction. Demyelination was observed only in the CO group and it was more severe and persisted longer than that observed in the low O₂ group. Moreover, in the CO group, decreased in microglial cell numbers were observed using flow cytometry, and microglia with detached branches were observed were observed using immunohistochemistry. Conversely, microglial cells with shortened branches and enlarged somata were observed in the low O₂ group. Furthermore, mRNAs encoding several neurotrophic factors expressed by microglia were decreased in the CO group but were increased in the low O₂ group. Thus, CO-induced DE displayed distinctive pathological features from those of simple hypoxic insults: prolonged demyelination accompanying a significant decrease in microglial cells. Decreased neurotrophic factor expression by microglial cells may be one of the causes of CO-induced DE.

Dynamic changes and clinical significance of serum S100B protein and glial fibrillary acidic protein in patients with delayed encephalopathy after acute carbon monoxide poisoning

Objective:

To study the dynamic changes and clinical significance of serum S100B protein and glial fibrillary acidic protein (GFAP) in patients with delayed encephalopathy after acute carbon monoxide poisoning (DEACMP).

Methods:

This study was conducted among DEACMP patients who were hospitalized from November 2014 to February 2016. Serum levels of S100B and GFAP in 66 DEACMP patients were measured by ELISA. Changes in patient states were examined dynamically using activities of daily living (ADL) scale, information-memory-concentration test (IMCT) and Hasegawa’s dementia scale (HDS), and compared with those of 64 patients without DE after ACMP.

Results:

Serum S100B [(0.59 ± 0.11) ng/ml] and GFAP [(227.67 ± 12.43) ng/ml] levels of DEACMP group in acute phase were significantly higher than those of ACMP group [(0.48 ± 0.10) ng/ml and (178.91 ± 11.47) ng/ml] and DEACMP group in recovery phase [(0.49 ± 0.12) ng/ml and (179.54 ± 12.32) ng/ml] (all P<0.05). Serum S100B and GFAP levels of DEACMP group were significantly correlated in both acute and recovery phases (r=0.432 in acute phase, P=0.007; r=0.378 in recovery phase, P=0.034). ADL, HDS and IMCT scores of DEACMP group in acute phase were (45.12 ± 3.12), (7.98 ± 1.02) and (9.61 ± 1.41) points respectively, which were significantly different from those of recovery phase [(33.25 ± 3.09), (16.13 ± 1.17) and (19.54 ± 1.43) points respectively] (P<0.05).

Conclusions:

DEACMP was accompanied by secondary brain injury, for which glial activation may be important. Serum S100B and GFAP levels may be related to prognosis.

iTRAQ-based differential proteomic analysis of the brains in a rat model of delayedcarbon monoxide encephalopathy

Delayed encephalopathy after acute carbon monoxide poisoning (DEACMP) is a difficult-to-manage neurological complication that can severely affect the life quality of patients. Although the central nervous system (CNS) injuries have been reported, the underlying molecular mechanisms are still unclear. Therefore, we established a rat model of DEACMP, applying isobaric tags for a relative and absolute quantification (iTRAQ)-based proteomics approach to identify differentially expressed proteins in cerebral tissue. A total of 170 proteins in the CO exposure groups were identified as differentially changed. Bioinformatics analysis suggested that these proteins are mainly involved in the biological processes, such as energy metabolism and many neurodegenerative diseases. Three proteins, Glial fibrillary acidic protein (GFAP), mitochondrial malate dehydrogenase (MDHM), and isocitrate dehydrogenase [NAD] subunit alpha (IDH3A), were identified as playing important roles in CNS injuries in DEACMP, and were successfully confirmed by immunohistochemistry analysis. Our study not only offers us new insights into the pathophysiological mechanisms of CNS injuries in DEACMP, but also may provide clinicians with important references in early prevention and treatment.

[Effects of extract of Ginkgo biloba on magnetic resonance imaging and electroencephalography in patients with delayed encephalopathy after acute carbon monoxide poisoning]

Objective: To observe the effects of extract of Ginkgo biloba (Ginaton) on magnetic resonance imaging (MRI) and electroencephalography (EEG) in patients with delayed encephalopathy after acute carbon monoxide poisoning. Methods: The 84 patients with delayed encephalopathy after acute carbon monoxide poisoning treated in our hospital from Jan. 2011 to Apr. 2016 were randomly divied into therapy group and observation group. The therapy group received routine treatments of hyperbaric oxygen, cure cerebral edema and promote brain cell metabolism, and observation group was given intravenous injection (intravenous drip) Ginaton 70 mg (adding 0.9% sodium chloride injection 250 ml) , once a day, 2 weeks for one therapeutic course. The changes of MRI and EEG before and after treatment between therapy group and observation group were observed. Results: In the observation group, the white matter and globus pallidus lesions of 14 d after treatment were smaller than those in the treatment group, and the abnormal signal intensity was decreased. At 14 days after treatment the improvement of EEG in observation group were better than therapy group (P<0.05) . Conclusion: Early treatment of extract of Ginkgo biloba (Ginaton) in delayed encephalopathy after acute carbon monoxide poisoning can effectively improve lesion and signal on MRI and abnormal rate on EEG. It has a certain therapeutic effect in clinical.