Magnetic resonance imaging findings in chronic carbon monoxide intoxication

To define the cranial magnetic resonance imaging (MRI) features of the chronic stage of carbon monoxide (CO) poisoning in patients with and without neuropsychiatric sequelae.

Eight patients who had neither symptoms nor neurological sequelae and eight patients with neuropsychiatric sequelae were included in the study. Patients aged between 9 to 57 (mean 32.2 years). All patients had been comatose at initial admittance and awoke after normobaric 100% oxygen therapy within 1-7 days. In this study, the patients were being examined with routine cranial MRI between 1 and 10 years (mean 3.4 years) after exposure to CO.

The most common finding was bilateral symmetric hyperintensity of the white matter, which was more significant in the centrum semiovale, with relative sparing of the temporal lobes and anterior parts of the frontal lobes on T2-weighted and FLAIR images in all patients. Cerebral cortical atrophy was seen in 10 patients; mild atrophy of cerebellar hemispheres in 8; and vermian atrophy in 11. Corpus callosum was atrophic in one patient. Bilateral globus pallidus lesions were seen in three patients. The lesions were hypointense on T1-weighted images and hyperintense on T2-weighted and FLAIR images.

Patients with severe CO intoxication may develop persistent cerebral changes independently of their neuropsychiatric findings in the chronic stage. They may present with characteristic MRI findings as described here, even if asymptomatic. The history of CO exposure is therefore helpful for recognizing and interpreting the MRI findings of chronic stage CO intoxication.