Serial cerebral MRI with FLAIR sequences in acute carbon monoxide poisoning

In a patient with acute carbon monoxide (CO) poisoning in whom no delayed sequelae have been observed, MRI was performed serially from the time of exposure. When few clear findings were noted on conventional T2-weighted spin echo (SE) imaging, distinct hyperintense areas in the deep cerebral white matter were already evident on fluid attenuated inversion recovery (FLAIR) pulse imaging. These abnormal findings appeared to reflect a disease process differing from the acute phase disturbance of consciousness, namely the course of a gradually progressive demyelination. Neither serial intelligence tests nor single photon emission CT (SPECT) studies of regional cerebral blood flow conducted in the same period revealed any abnormalities. These results suggest that, in the subclinical phase in which there are few significant findings on T2-weighted SE imaging or SPECT, insidious demyelinating changes are already apparent on FLAIR imaging and that FLAIR imaging may thus be useful in the early diagnosis of the interval form of CO poisoning.