Hypoxic-ischemic encephalopathy and hyperoxygenation

Case contributed by Frank Gaillard


Found at home GCS 5 and severe hypoxia. No trauma, unknown period of illness. EEG concerning for severe anoxic brain injury. Not in status epilepticus.

Patient Data

Age: 60 years
Gender: Male

Minor diffusion restriction is seen in the hippocampi bilaterally, as well as probably the basal ganglia. The cerebral cortex appears bright on FLAIR, perhaps a little swollen but does not definitely demonstrate reduced ADC values, although this is difficult to accurately characterize. 

Pachymeningeal enhancement and effusion are in keeping with a recent lumbar puncture. 

SWI demonstrates an absence of veins seen on SWI and minIP projections. This is attributable to hyperoxygenation. A left forceps major microhemorrhage is also noted. 

Case Discussion

Hyperoxygenation can not only cause abnormally elevated FLAIR signal in sulci, potentially causing confusion and suggesting blood or meningitis, but also interfere with the normal signal loss seen on SWI from deoxygenated hemoglobin. Oxygen in hemoglobin "shields" the iron molecules from exerting T2* effects 1

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