Delayed encephalopathy after carbon monoxide intoxication--long-term prognosis and correlation of clinical manifestations and neuroimages.

In order to understand the correlation between the clinical and neuroimaging manifestations and the long-term prognosis in delayed encephalopathy after carbon monoxide (CO) intoxication, we retrospectively reviewed 12 patients who had delayed encephalopathy from 89 patients with CO intoxication. There were 8 men and 4 women, with a mean age of 54.4 +/- 17.2 years (range: 11-79 years). All patients had prominent consciousness disturbance in the acute stage and received high flow of O2 or hyperbaric oxygen therapy. All of them regained consciousness within 1-7 days, but subsequently developed delayed encephalopathy. The delayed encephalopathy occurred from 14 to 45 days after recovery from the acute stage. The clinical manifestations included cognitive impairment, akinetic mutism, sphincter incontinence, gait ataxia and extrapyramidal syndromes such as chorea, dystonia, and parkinsonism. Brain MRI revealed multiple lesions in the subcortical white matter and basal ganglia, mostly in the globus pallidus, and to a lesser degree in the putamen, and caudate. In the follow-up period, sphincter incontinence first disappeared. The cognitive impairment improved greatly in the following few months, but the involuntary movements were improved only slightly. Some patients had persistent neurological sequelae, such as dystonia. Similary, the follow-up brain MRI showed a steady improvement. In conclusion, the delayed encephalopathy usually developed 2 weeks to 1.5 months after the acute phase of CO intoxication. Globus pallidus and subcortical white matter were commonly involved. The neurological manifestations improved and correlated roughly with the neuroimaging changes.