Predictors for delayed encephalopathy following acute carbon monoxide poisoning.

BACKGROUND: In Japan, many carbon monoxide (CO) poisoning cases are transported to emergency settings, making treatment and prognostic assessment an urgent task. However, there is currently no reliable means to predict whether "delayed neuropsychiatric sequelae (DNS)" will develop after acute CO poisoning. This study is intended to find out risk factors for the development of DNS and to characterize the clinical course following the development of DNS in acute CO poisoning cases. METHODS: This is a retrospective cohort study of 79 consecutive patients treated at a single institution for CO poisoning. This study included 79 cases of acute CO poisoning admitted to our emergency department after attempted suicide, who were divided into two groups consisting of 13 cases who developed DNS and 66 cases who did not. The two groups were compared and analyzed in terms of clinical symptoms, laboratory findings, etc. RESULTS: Predictors for the development of DNS following acute CO poisoning included: serious consciousness disturbance at emergency admission; head CT findings indicating hypoxic encephalopathy; hematology findings including high creatine kinase, creatine kinase-MB and lactate dehydrogenase levels; and low Global Assessment Scale scores. The clinical course of the DNS-developing cases was characterized by prolonged hospital stay and a larger number of hyperbaric oxygen (HBO) therapy sessions. CONCLUSION: In patients with the characteristics identified in this study, administration of HBO therapy should be proactively considered after informing their family, at initial stage, of the risk of developing DNS, and at least 5 weeks' follow-up to watch for the development of DNS is considered necessary.

1H-magnetic resonance spectroscopy indicates damage to cerebral white matter in the subacute phase after CO poisoning.

OBJECTIVE: The authors examined whether (1)H-magnetic resonance spectroscopy (MRS) can identify damage to the centrum semiovale in the subacute phase after CO exposure. METHODS: Subjects comprised 29 adult patients who were treated with hyperbaric oxygenation within a range of 4-95 h (mean 18.7 h) after CO exposure. Subjects were classified into three groups according to clinical behaviours: Group A, patients with transit acute symptoms only; Group P, patients with persistent neurological symptoms; and Group D, patients with 'delayed neuropsychiatric sequelae' occurring after a lucid interval. MRS of bilateral centrum semiovale was performed 2 weeks after CO inhalation for all patients and 13 healthy volunteers. The mean ratios of choline-containing compounds/creatine ((mean)Cho/Cr) and N-acetylaspartate/Cr ((mean)NAA/Cr) for bilateral centrum semiovale were calculated and compared between the three CO groups and controls. Myelin basic protein (MBP) concentration in cerebrospinal fluid was examined at 2 weeks to evaluate the degree of demyelination in patients. RESULTS: MBP concentration was abnormal for almost all patients in Groups P and D, but was not abnormal for any Group A patients. The (mean)Cho/Cr ratios were significantly higher in Groups P and D than in Group A. No significant difference in (mean)NAA/Cr ratio was seen between the three pathological groups and controls. A significant correlation was identified between MBP and (mean)Cho/Cr ratio. CONCLUSIONS: These results suggest that the Cho/Cr ratio in the subacute phase after CO intoxication represents early demyelination in the centrum semiovale, and can predict chronic neurological symptoms.