Carbon monoxide poisoning
Carbon monoxide (CO) is a gas odorless, colourless, tasteless, and non-irritating gas that may come from smoke, fuel-burning devices, motor vehicles, boats, and workplace exposure among others. It has approximately 240 times the binding affinity to hemoglobin compared to oxygen, and subsequently reduces the ability of hemoglobin to provide oxygen to peripheral tissues. CO also interferes with how the body utilizes oxygen by impairing mitochondrial function, among other non-hemoglobin related effects. CO and cyanide have been observed to have synergistic effects on oxygen transport and utilization when combined, such as in smoke inhalation.
Patients may typically present with headache, malaise, nausea, dizziness, and acute myocardial injury in an acute setting of carbon monoxide poisoning. Mental status may range from mild confusion to coma, depending on the severity of exposure. It has been reported in up to 40% of patients that a delayed neuropsychiatric syndrome may occur in those with significant CO exposure, characterized by different severities of cognitive deficits, personality changes, movement disorders and focal neurologic deficits. Chronic CO exposure may be harder to identify, but patients may have cognitive decline, gait abnormalities, and fecal incontinence.
On MRI, bilateral changes are typically seen with the globus pallidus most commonly affected, along with the brain white matter. Other areas that may be involved include: putamen, thalamus, caudate nucleus, cerebral cortex and the hippocampus among others. On T1-weighted imaging, the involved regions in the brain will appear hypointense or iso-intense, and hemorrhages may appear with high signal. With contrast, peripheral enhancement may be observed in the affected areas in the acute phase, such as the globus pallidi. On T2/FLAIR imaging, the areas will be hyperintense. On diffusion-weighted imaging, it would be expected to see increased diffusion signals from the affected areas in the acute phase.
References
1. Kim DM, Lee IH, Park JY, Hwang SB, Yoo DS, Song CJ. Acute carbon monoxide poisoning: MR imaging findings with clinical correlation. Diagn Interv Imaging. 2017;98(4):299-306.
2. O’Donnell P, Buxton PJ, Pitkin A, Jarvis LJ. The magnetic resonance imaging appearances of the brain in acute carbon monoxide poisoning. Clin Radiol. 2000;55(4):273-280.
4. https://radiopaedia.org/articles/carbon-monoxide-poisoning-1