Cranial MR imaging findings of carbon monoxide poisoning in asymptomatic patients in the chronic stage.

PURPOSE: To describe MR imaging findings of the chronic stage of carbon monoxide poisoning in asymptomatic patients. MATERIALS AND METHODS: Clinical data of 34 patients, who had been admitted to our hospital for carbon monoxide poisoning were reviewed and invited for control evaluation. Of the patients who accepted, ten who had no symptoms and neurological sequelae in the physical examination were included in the study. All patients had been in coma on initial admittance and had awakened after normobaric 100% oxygen therapy 1-10 years ago. Their ages were between 22-57 years (mean, 36.2 years). All patients were examined with cranial MR imaging. RESULTS: The most common finding was bilateral symmetric hyperintensity of the white matter more evident in the centrum semiovale with relative sparing of temporal lobes and anterior parts of frontal lobes on T2-weighted and FLAIR images in all patients. Subcortical U-fibers were intact in all patients. Cerebral cortical atrophy of variable degrees was seen in eight patients, mild atrophy of cerebellar hemispheres in seven patients, and vermian atrophy in nine patients. Corpus callosum was atrophic in two patients. Bilateral globus pallidus lesions were seen in three patients as hypointense on T1-weighted and hyperintense on T2-weighted and FLAIR images. CONCLUSION: Cerebral changes may be present in patients with severe CO poisoning even when the patient becomes asymptomatic. Knowledge of these findings would be helpful when evaluating these patients for follow-up or for other reasons.