[Magnetic resonance imaging could predict delayed encephalopathy after acute carbon monoxide intoxication]

Some patients with acute carbon monoxide (CO) intoxication relapse into severe neuropsychiatric symptomes several weeks after the lucid interval. This serious neurological sequelae, delayed encephalopathy, is difficult to anticipate. Although magnetic resonance imaging (MRI) was reported to show characteristic findings, there has been few information on MRI during the lucid interval. We retrospectively reviewed MR images obtained within 15 days after the exposure, and analyzed whether MRI could predict delayed encephalopathy.

Retrospective, single-center study.

Sixteen serial patients with severe CO intoxication, who were found unconscious and underwent hyperbaric oxygen therapy, and in whom MR-imagings were performed at least once within 15 days after the exposure.

Although all 16 patients recovered consciouness, six of them (37.5 %) went into delayed encephalopathy (DE group) while the others did not (non-DE group). FLAIR images of all patients in DE group showed bilateral diffuse high intensity in white matter of centrum semiovale after the relapse of neuropsychiatric symptomes. In 4 of them, the identical findings were recognized earlier during the lucid interval. In contrast, no MR images of patients in non-DE group showed white matter hyperintensity (4/6 vs 0/10, p < 0.01). T2-hyperintensities in basal ganglia were seen not only in DE group (3 of 6 patients) but also in non-DE group (2 of 10). Diffusion-weighted images (DWI) were obtained in 10 patients (5 in each group). Although white matter hyperintensities in DWI were positive in 4 patients in DE group (none in non-DE group), 3 of them showed negative findings during the lucid interval.

Bilateral symmetric white matter hyperintensity in MRI (T2WI/FLAIR) could be a good predictor of delayed encephalopathy after acute CO intoxication.