UMEM Educational Pearls

Title: Subarachnoid Hemorrhage -- Or Is It?

Category: Neurology

Keywords: subarachnoid hemorrhage, mimic, pseudosubarachnoid hemorrhage, cerebral edema (PubMed Search)

Posted: 11/9/2016 by WanTsu Wendy Chang, MD
Click here to contact WanTsu Wendy Chang, MD

Question

Patient found pulseless after submersion in water for 20 minutes. After ROSC, patient’s GCS was 3 and pupils are dilated and nonreactive.

Answer

There is increased attenuation of the basal cisterns and subarachnoid space as well as diffuse cerebral edema.
At first glance, it appears to be a subarachnoid hemorrhage.
However, the Hounsfield unit of the density is lower than blood.
This is a pseudosubarachnoid hemorrhage sign.
This can be seen in anoxic injury with cerebral edema, pyogenic meningitis, venous sinus thrombosis, bilateral large subdural hemorrhages.

References

Kim JM, Eom TH. The pseudosubarachnoid hemorrhage: clinical implications of subarachnoid hemorrhage misdiagnosis. Pediatr Emerg Care. 2016 May 12. [Epub ahead of print]

Follow me on Twitter @EM_NCC