Long-term outcome of delayed neuropsychiatric sequelae after carbon monoxide poisoning

OBJECTIVE: Delayed neuropsychiatric sequelae (DNS) following carbon monoxide (CO) poisoning, which may result from a demyelinating leukoencephalopathy, is a disease with a poor prognosis. This study examined the factors affecting the long-term prognosis of DNS and the efficacy of hyperbaric oxygen therapy (HBOT) in patients with DNS. METHODS: This retrospective study included 84 patients with DNS following CO poisoning from January 2013 to June 2016. HBOT was given to 24 patients. The patients were divided into an improvement group and non-improvement group based on their clinical condition on a telephone interview at intervals between 3 months and 3 years after the onset of DNS. The improvement group was defined as having Cerebral Performance Category (CPC) scores in their daily life that improve to 1 or 2 grade. RESULTS: Of the 594 patients, DNS were found in 18.2%, and 70.2% (59 of 84) of the patients with DNS improved. The prognostic factors for the improvement of DNS were an age of 45 years or less (odds ratio [OR], 12.068; 95% confidence interval [CI], 2.393–60.858; P 0.1). CONCLUSION: Patients aged less than 45 years, low grade CPC score of 1 and 2, and lucid interval longer than 20 days are more likely to have a good prognosis. On the other hand, HBOT failed to produce a benefit for DNS patients.

Can Predict Late Encephalopathy by Diffusion Tensor Imaging in Acute Phase of Carbon Monoxide Poisoning?

PURPOSE: Approximately 30% of patients with acute carbon monoxide (CO) poisoning display chronic neurological symptoms due to late encephalopathy, 1/3 in delayed neuropsychiatric sequelae (DNS) and 2/3 in persistent neurological symptoms (PNS). This study was conducted in order to determine whether diffusion tensor imaging (DTI) can sensitively represent damage to the brain in the acute phase after CO poisoning. METHODS: This prospective study included 132 patients with CO poisoning from February 2013 to February 2014. The patients were classified according to three groups: patients with asymptomatics; patients with PNS; and patients with DNS. Mean fractional anisotrophy (FA) and apparent diffusion coefficient (ADC) of regions of interest (ROI) in the acute phase were compared between the DNS or PNS groups and the asymptomatic group. DNS was considered present when the patient had clinical symptoms and signs of DNS within six weeks after exposure to CO poisoning. RESULTS: Late encephalopathy occurred at a rate of 18.9% (12.1% in the DNS, 6.7% in the PNS). DTI cannot sensitively represent brain damage of the DNS groups in the acute phase after CO poisoning. But low FA values of high frontal subcortex and low ADC values of globus pallidus in the DNS group clearly differed from those in the asymptomatic group. The PNS group showed significantly low FA and ADC values in centrum semiovale, several subcortics, globus pallidus, corpus callosum, and internal capsule. No significant difference in ADC was observed between patient groups. CONCLUSION: In the acute phase of CO poisoning, FA or ADC values sensitively represented damage to white matter in the some subcortex. However it had limited value in predicting the DNS because of no significant reduction of FA value in the centrum semiovale in the acute phase. However low values of FA and ADC in diffuse lesions in deep white matter and subcortex is a powerful predictor of the PNS.

Acute Carbon Monoxide Poisoning: Prognostic Factors for Delayed Neuropsychiatric Sequelae

PURPOSE: Delayed neuropsychiatric sequelae (DNS), which are thought to arise from delayed post-hypoxic leukoencephalopathy, commonly occur after recovery from acute carbon monoxide (CO) poisoning. This study was conducted in order to determine the prognostic factors for DNS in patients with CO poisoning. METHODS: This prospective study included 200 patients with CO poisoning from January 2009 to December 2013. We compared clinical variables between patients with (n=52) and without DNS (n=148). DNS was considered present when the patient had clinical symptoms and signs of DNS within six weeks after exposure to CO poisoning. RESULTS: DNS occurred at a rate of 26.0%. In univariate analysis, the prognostic factors for DNS were loss of consciousness, duration of unconsciousness, Glasgow coma scale, peripheral neuropathy, hypotension, elevated cardiac enzyme at admission, and magnetic resonance imaging (MRI) findings at admission (p<0.05), however, in multivariate analysis, the only independent prognostic factor for DNS was initial MRI findings (OR=16.977, 95% CI=3.051-94,476). Abnormal MRI findings showed significant association with DNS in both the normobaric oxygen therapy and hyperbaric oxygen therapy groups. In patients with normal MRI findings, peripheral neuropathy could predict DNS. Among MRI abnormalities, lesions in the deep white matter (OR=24.719, p=0.000) and globus pallidus (OR=7.062, p=0.001) showed significant association with DNS. Patients with DNS had good prognosis (activity of daily living of grade 1 and 2) of 86.5% and mortality of 5.8% after six months. CONCLUSION: Initial MRI finding can be used in predicting late sequelae in patients with CO poisoning.