DIAGNOSIS:
Cerebral Fat Embolism
The MRI brain showed punctuate, non-confluent lesions showing restricted diffusion (Figs. 1 and 2), in the capsuloganglionic region and the splenium of the corpus callosum turning bright on the T2W images as seen in a more superior section (Fig. 3) in the centrum semiovale.
Fat embolism occurs in all patients with displaced fractures of long bones, though it is mostly subclinical (1, 2). The free fatty acids, produced by hydrolysis of triglycerides are usually bound to serum albumin. The unbound free fatty acids may cause mechanical obstruction of the arterial circulation (3).
The systems involved are respiratory, skin and nervous system with respiratory failure, and petechial skin hemorrhages. Cerebral fat embolism manifests with headache, irritability, stupor, convulsion and coma. Blunt carotid trauma and vertebro-basilar thrombosis are the clinical differentials (4).
MRI, especially diffusion imaging is more sensitive. Punctate T2 hyperintensities are seen distributed in the cerebral white matter, deep gray matter nuclei and the brain stem, representing fat embolism induced ischemic lesions. The imaging differentials are diffuse axonal injuries and white matter demyelinating lesions. A non-head injury patient with a history of trauma, who after 24-36 hours develops neurological deterioration, should be suspected to have fat embolism. In an appropriate clinical setting, the MRI findings are highly suggestive of the diagnosis.
The treatment involves good hydration and restoration of intravascular volumes.
References:
1. Nissar S., Ashok P., Venkatraman B., Marie A. K. Fat Embolism syndrome .Clinical and imaging consideration: case report and review of the literature: Indian journal of critical care medicine, 2008;12(1):32-36
2. Andrew D. S., John L. U., and James M. S. : Contrast-Enhanced MR Imaging of Cerebral Fat Embolism: Case Report and Review of the Literature
AJNR Am J Neuroradiol 2003, 24:97–101,
3. Hak J. K., Jong H.L., Chang H.L., Suk Hong L., Tae Yong M.,
Byung M. C., Hae Kyu K., Byung Rae P., and Kee Hyun C. Experimental Cerebral Fat Embolism: Embolic Effects of Triolein and Oleic Acid Depicted by MR Imaging and Electron Microscopy AJNR Am J Neuroradiol 2002, 23:1516–1523,
4. Parizel M., Demey H.E., Veeckmans G., Verstreken F., Cras P., Jorens P.G. and De Schepper A.M.: Early diagnosis of cerebral fat embolism syndrome by diffusion- weighted MRI (starfield pattern) Stroke. 2001; 32; 2942-2944
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