1. Teaching NeuroImages 50 year old woman underwent therapeutic hypothermia after a witnessed cardiac arrest Teaching NeuroImages Neurology Resident and Fellow Section © 2013 American Academy of Neurology

2. Vignette A 50 year-old woman underwent therapeutic hypothermia after a witness cardiac arrest and cardiac catheterization A 24-hour head CT showed diffuse hyperattenuation in the subarachnoid space and reported as massive diffuse subarachnoid hemorrhage. Repeat CT at 48 hours showed significant clearing of the previously read‘subarachnoid hemorrhage’. Mohamed et al. © 2013 American Academy of Neurology Mohamed et al.

3. Imaging Mohamed et al. © 2013 American Academy of Neurology Mohamed et al.

4. ‘Subarachnoid Hemorrhage’ From Decreased Contrast Elimination after Therapeutic Hypothermia Cerebro-circulatory arrest and reperfusion causes injury that breaks down the blood-brain barrier. 1 In patients undergoing contrast imaging, there may be active extravasation of contrast into the subarachnoid space. Hypothermia alters contrast viscosity, decreases glomerular filtration and subsequently decreases elimination of the contrast. 2 It is important to recognize such mimickers of subarachnoid hemorrhage in the era of hypothermia. Mohamed et al. © 2013 American Academy of Neurology