Neurovascular syndrome
Total-body exposures in the range of 50 Gy and more induce this syndrome within 1–72 h, leading to death within a few days. Some symptoms may occur as low as 20 Gy. Early symptoms include nausea and vomiting. Death likely is due to collapse of the circulatory system as well as increased pressure in the confining cranial vault as the result of increased fluid content caused by edema, vasculitis, and meningitis. (Adapted from ICRP Publication 118, 2012)
ICRP Glossary entry - June 2019