Novel clinical grading of delayed neurologic sequelae after carbon monoxide poisoning and factors associated with outcome.

INTRODUCTION: Delayed neurologic sequelae (DNS) after carbon monoxide (CO) poisoning manifest as a relapse of neurologic deficits. However, the long-term outcome of DNS has not been fully clarified. Myelin basic protein (MBP) levels in the cerebrospinal fluid (CSF) have been reported to be elevated in DNS. However, the precise timing and clinical value of the CSF examination have not been fully evaluated. We aimed to clarify the long-term outcome and the factors predicting the outcome of DNS and to evaluate the utility of CSF-MBP for predicting the development and severity of DNS. METHODS: This work was designed as a single-center, prospective, observational study. We graded DNS severity as Grade 1 (consistent independence), Grade 2 (temporary dependence), or Grade 3 (persistent dependence). We analyzed the percentage categorized in each grade and the parameters associated with outcome. RESULTS: Of 100 patients experiencing acute CO poisoning (median age: 46 years; 69% male), 20 (20%) developed DNS, including six Grade 1 (30%), ten Grade 2 (50%), and four Grade 3 (20%) cases. The Grade 3 patients [median: 77 years; interquartile range (IQR): 76-82] were older than the Grade 1 patients [42; 30-46] (P<0.01); the DNS onset of the Grade 1 patients [median interval after poisoning: 35 days; IQR: 32-56] occurred later than that of the Grade 3 patients [10; 9-13] P<0.001) and the Grade 2 patients [25; 23-27] (P<0.05). The CSF-MBP levels of the DNS patients were higher than those of the non-DNS patients (P<0.0001). The 1-month CSF-MBP levels of the Grade 3 patients were higher than those of the Grade 1 patients (P<0.05); the MBP index, defined as [(Age)×(1-month CSF-MBP)], was higher in the Grade 3 patients than in the Grade 1 patients (P<0.01). Severe DNS were associated with advanced age (>72.5 years), earlier onset (<18 days), higher 1-month CSF-MBP (>252 pg/ml), and higher MBP index (>20.9 year × ng/ml). CONCLUSIONS: Poor DNS outcomes were associated with advanced age and earlier onset. CSF-MBP can serve as a sensitive predictor of both the development and outcomes of DNS.

Fractional anisotropy in the centrum semiovale as a quantitative indicator of cerebral white matter damage in the subacute phase in patients with carbon monoxide poisoning: correlation with the concentration of myelin basic protein in cerebrospinal fluid.

Carbon monoxide (CO) poisoning leads to demyelination of cerebral white matter (CWM) fibers, causing chronic neuropsychiatric symptoms. To clarify whether fractional anisotropy (FA) from diffusion tensor imaging in the centrum semiovale can depict demyelination in the CWM during the subacute phase after CO inhalation, we examined correlations between FA in the centrum semiovale and myelin basic protein (MBP) in cerebrospinal fluid. Subjects comprised 26 adult CO-poisoned patients ≤60 years old. MBP concentration was examined for all patients at 2 weeks after CO inhalation. The mean FA of the centrum semiovale bilaterally at 2 weeks was also examined for all patients and 21 age-matched healthy volunteers as controls. After these examinations, the presence of chronic symptoms was checked at 6 weeks after CO poisoning. Seven patients displayed chronic symptoms, of whom six showed abnormal MBP concentrations. The remaining 19 patients presented no chronic symptoms and no abnormal MBP concentrations, with MBP concentrations undetectable in 16 patients. The MBP concentration differed significantly between patients with and without chronic symptoms. The mean FA was significantly lower in patients displaying chronic symptoms than in either patients without chronic symptoms or controls. After excluding the 16 patients with undetectable MBP concentrations, a significant correlation was identified between MBP concentration and FA in ten patients. The present results suggest that FA in the centrum semiovale offers a quantitative indicator of the extent of demyelination in damaged CWM during the subacute phase in CO-poisoned patients.

Elevated S100B level in cerebrospinal fluid could predict poor outcome of carbon monoxide poisoning.

OBJECTIVE: S100B is a calcium-binding protein produced by astroglia in the brain and has been used as a marker of neuronal damage after brain trauma. We investigated the utility of S100B in cerebrospinal fluid (CSF) measured during the early phase of carbon monoxide (CO) poisoning in predicting the subsequent clinical course. METHODS: The study included 31 patients who were admitted to the hospital with loss of consciousness following CO poisoning. S100B levels were measured by enzyme-linked immunosorbent assay in CSF, and serum samples collected simultaneously within 24 hours and on the fourth day after CO exposure. All patients were followed for at least 3 months and divided into 3 groups based on the clinical course: persistent vegetative state (PVS), delayed encephalopathy (DE), and complete recovery with no complications (NC). RESULTS: During the 3-month period, 3 patients developed PVS, 5 developed DE, and 23 were classified as NC. The mean S100B levels in the CSF within 24 hours after CO exposure were higher in the PVS group (9.25 ng/mL) than in the DE (2.03 ng/mL) and NC groups (1.86 ng/mL). However, the mean serum S100B levels were not elevated in the 3 groups (0.21, 0.59, and 0.16 ng/mL, respectively). CONCLUSION: Early elevation of S100B in CSF after CO poisoning could be a suitable predictor of subsequent development of PVS.

[Clinical significance of 5-HT and DA levels in serum and cerebrospinal fluid of the patients with delayed encephalopathy after acute carbon monoxide poisoning].

OBJECTIVE: To explore the changes and the clinical significance of 5-hydroxytryptamine (5-HT), dopamine (DA) levels in serum and cerebrospinal fluid (CSF) of patients with delayed encephalopathy (DEACMP) after acute carbon monoxide poisoning. METHODS: The dynamic detection of 5-HT and DA levels in serum and CSF from 42 patients with DEACMP was performed with high performance liquid chromatography (HPLC). The condition changes of patients with DEACMP were analyzed with three types of scales: the activity of daily living scale (ADL), information memory concentration test (IMCT) and Hasegawa's dementia scale (HDS); these changes were compared with those from 38 other encephalopathy patients and 38 non-encephalopathy patients, respectively. RESULTS: Before treatment, the serum 5-HT and DA levels [(662.61 ± 178.50) and (155.74 ± 60.32) nmol/L, respectively] of DEACMP group were both significantly lower than those [(914.08 ± 198.04) and (225.70 ± 48.53) nmol/L] of non-encephalopathy group (P < 0.05); the serum DA level of DEACMP group was also significantly lower than that [(243.57 ± 66.94) nmol/L] of other encephalopathy group (P < 0.05); the serum 5-HT level of DEACMP group was not significantly different from that [(729.54 ± 299.87) nmol/L] of other encephalopathy group (P > 0.05). After treatment, the serum 5-HT and DA levels [(714.08 ± 170.47) and (192.18 ± 33.07 nmol/L, respectively)] of DEACMP group elevated to various extent, but only serum DA level was significantly higher than that before treatment (P < 0.05). Before treatment, the CSF 5-HT and DA levels of DEACMP group were significantly lower than those of non-encephalopathy group and those of other encephalopathy group (P < 0.05). After treatment, the CSF 5-HT level (232.44 ± 54.28 nmol/L) was similar to normal level and significantly higher than that before treatment (P < 0.05); the CSF DA level [(56.83 ± 12.85) nmol/L] of DEACMP group increased only slightly (P > 0.05). In DEACMP group, ADL score (50.64 ± 7.23), HDS score (8.55 ± 8.08) and IMCT score (4.95 ± 7.30) before treatment were significantly different from those (8.5 ± 8.08, 4.95 ± 7.30 and 15.64 ± 10.90) after treatment (P < 0.01). In DEACMP group, there wasa negative correlation between DA level changes and HDS score changes, when the DA levels and HDS scores before treatment were compared with those after treatment (P < 0.05). CONCLUSION: The dynamic changes of 5-HT and DA levels in serum and CSF of patients with DEACMP consisted basically with the patient's condition change. The dynamically detected 5-HT and DA levels can be used as the biological indicators to reflect the condition change and treatment effects of DEACMP patients.

The early elevation of interleukin 6 concentration in cerebrospinal fluid and delayed encephalopathy of carbon monoxide poisoning.

OBJECTIVE: This study was designed to investigate whether interleukin 6 (IL-6) in cerebrospinal fluid (CSF) in the early phase of carbon monoxide (CO) poisoning can be a predictive marker of delayed encephalopathy (DE). METHODS: Nine patients with CO poisoning were included in the study. Cerebrospinal fluid was sampled within 24 hours of the last exposure to CO, on hospital day 4, and once a week for at least 1 month to determine IL-6 and myelin basic protein concentrations. All patients were followed at least 3 months. RESULTS: Three patients demonstrated significant early IL-6 elevation in CSF, normal IL-6 level in CSF on day 4, and significant delayed myelin basic protein elevation in CSF. The 2 patients with the highest early IL-6 elevation in CSF developed DE. Interleukin 6 in serum was not related to DE. CONCLUSION: Interleukin 6 in CSF at the early phase of CO poisoning may be a predictive marker of DE.

Myelin basic protein in cerebrospinal fluid: a predictive marker of delayed encephalopathy from carbon monoxide poisoning.

This study was designed to investigate whether myelin basic protein (MBP) in cerebrospinal fluid (CSF) can be a predictive marker of delayed encephalopathy from carbon monoxide (CO) poisoning. Five patients with CO poisoning were included in the study. The CSF was serially sampled to determine the MBP concentration. All patients were classified into group DE or group non-DE according to whether delayed encephalopathy developed or not. In all 3 patients in group DE, the MBP levels in the CSF were markedly elevated preceding the clinical manifestations of delayed encephalopathy. In both group non-DE patients, the MBP concentrations in the CSF were never elevated. Elevated MBP concentrations in the CSF may represent a predictive marker of delayed encephalopathy from CO poisoning, leading to a more appropriate triage of patients with CO poisoning.

[The changes of soluble interleukin-2 receptor in serum and cerebrospinal fluid of patients with delayed encephalopathy after acute carbon monoxide poisoning].

OBJECTIVE: To explore the changes of soluble interleukin-2 receptor(sIL-2R) in serum and cerebrospinal fluid (CSF) of patients with delayed encephalopathy after acute carbon monoxide poisoning (DEACMP). METHODS: There were 31 patients with DEACMP, 32 patients with other encephalopathy and 31 controls in this study. The levels of sIL-2R in serum and CSF were detected by ELISA. RESULTS: Serum sIL-2R in patients with DEACMP[(329.21 +/- 160.99)U/ml] was significantly higher than that in control[(115.67 +/- 89.58) U/ml, P < 0.05)], but not significantly different from that in the other encephalopathy group[(367.50 +/- 123.14) U/ml, P > 0.05)]. CSF sIL-2R in patients with DEACMP[(54.48 +/- 43.04) U/ml] measured a little before discharge was significantly lower than that in patients with the other encephalopathy[(110.24 +/- 76.56) U/ml, P < 0.05)], but not significantly different from that in the control group[(34.96 +/- 22.70)U/ml, P > 0.05)]. At the pre-discharged period, CSF sIL-2R in patients with DEACMP[(100.26 +/- 93.65) U/ml] was significantly higher than that at the early stage of hospitalization[(52.28 +/- 43.31) U/ml, P < 0.05)]. No significant difference in serum sIL-2R was found between early stage of hospitalization[(338.34 +/- 161.53) U/ml] and pre-discharge [(351.31 +/- 175.93) U/ml, P > 0.05)]. CONCLUSION: The occurrence of DEACMP may be related with immunopathological damage. The sIL-2R levels in serum and CSF may give information about the state of immunological function of the patients with DEACMP and may contribute to determining the patient's condition and prognosis.

The effects of acute carbon monoxide intoxication on the cerebral energy metabolism of the rat.

The cerebal metabolic effects of 60 min exposure to 0.5, 1.0, 1.5, and 2.0% carbon monoxide (CO) and 60 min exposure to 1.0% CO were studied in lightly anesthetized rats by measurement of brain tissue contents of glycolytic and citric acid cycle intermediates, as well as tissue energy phosphates. The results indicate that cerebral energy homeostasis is maintained until advanced levels of CO intoxication (2.0%) are reached. Animals exposed to 2.0% CO developed significant decreases in systemic blood pressure, with attendent decreases in cerebral ATP, increases in ADP and AMP, plus early depletions of tissue citrate and alpha-oxyglutarate. The similarity of this pattern to that previously documented for various cerebral oligemic states suggests a possible modifying role for altered cerebral production in its production. A correlation between conscious behavior and cerebral energy state was suggested by the observation that unanesthetized animals exposed to 1.0% CO for 30 and 60 min retained consciousness, whereas animals exposed to 2.0% CO for 30 min became unresponsive late on in the exposure. A comparison of CO induced changes in intermediary metabolites, energy phosphates, intracellular pH, and cytoplasmic redox state with those seen in hypoxemia indicate no basic qualitative or quantiative differences in the metabolic response of brain tissue to the two conditions.