Case 4
History:
45 year old male status post cardiac arrest with alteration of level of consciousness
Findings:
Diffusion images showing increase signal involving the deep and cortical gray matter as well as hippocampi
Diagnosis:
Severe hypoxic ischemic injury (HII)
Discussion:
Severe hypoxic ischemic injury (HII) in adults primarily affects the gray matter structures: the basal ganglia, thalami, cerebral cortex, cerebellum, and hippocampi. CT is generally the initial imaging and may show diffuse edema with effacement of the CSF spaces, decreased cortical gray matter attenuation with loss of normal gray-white differentiation, and decreased bilateral basal ganglia attenuation. Diffusion-weighted MR imaging is the earliest imaging modality to become positive, usually within the first few hours after a hypoxic-ischemic event. During the first 24 hours, diffusion-weighted imaging may demonstrate increased signal intensity in the cerebellar hemispheres, basal ganglia, or cerebral cortex (in particular, the perirolandic and occipital cortices). The thalami, brainstem, or hippocampi may also be involved. DWI may pseudonormalize by the end of the first week.
References:
- Takahashi S, Higano S, Ishii K, et al. Hypoxic brain damage: cortical laminar necrosis and delayed changes in white matter at sequential MR imaging. Radiology 1993;189:449–456.
- Roychowdhury S, Maldjian JA, Galetta SL, Grossman RI. Postanoxic encephalopathy: diffusion MR findings. J Comput Assist Tomogr 1998;22:992–994.
- Benjamin Y. Huang, Mauricio Castillo, Hypoxic-Ischemic Brain Injury: Imaging Findings from Birth to Adulthood. RadioGraphics 2008;28:417-439
