White Matter Hyperintensities and Neuropsychological Outcome Following Carbon Monoxide Poisoning

Background: Carbon monoxide (CO) poisoning may result in white matter hyperintensities (WMH) and neurocognitive impairments.

Objective: To assess in a prospective study WMH in CO-poisoned patients and their relationship to cognitive functioning.

Methods: Seventy-three consecutive CO-poisoned patients were studied. MR scans and neurocognitive tests were administered on day 1 (within 36 hours after CO poisoning), 2 weeks, and 6 months. Age- and sex-matched control subjects for white matter analyses only were obtained from the authors' normative imaging database. MR scans were rated for WMH in the periventricular and centrum semiovale regions, using a 4-point rating scale. Two independent raters rated the scans, and a consensus was reached.

Results: Thirty percent of CO-poisoned patients had cognitive sequelae. Twelve percent of the CO-poisoned patients had WMH, with significantly more periventricular, but not centrum semiovale, WMH than control subjects. The WMH in CO-poisoned patients did not change from day 1 to 6 months. Centrum semiovale hyperintensities were related to worse cognitive performance. Duration of loss of consciousness correlated with cognitive impairment at all three times. Initial carboxyhemoglobin levels correlated with loss of consciousness but not with WMH or cognitive sequelae.

Conclusions: CO poisoning can result in brain injury manifested by WMH and cognitive sequelae. The WMH were not related to CO poisoning severity. The WMH occurred in both the periventricular and the centrum semiovale regions; however, only those in the centrum semiovale were significantly associated with cognitive impairments.