fever AE hyperpyrexia AE extreme pyrexia AE YH 10020741 SIDER: C0392676 Axelrod YK1, Diringer MN. Temperature management in acute neurologic disorders. Neurol Clin. 2008 May;26(2):585-603, xi. doi: 10.1016/j.ncl.2008.02.005. PMID: 18514828. hyperpyrexia AE is a fever adverse event that has an outcome of an excessive and unusual elevation of set body temperature greater than or equal to 41 °C. It is an extremely high fever. Such a high temperature is considered a medical emergency as it may indicate a serious underlying condition such as sepsis. HPO: HP_0001945 WEB: http://en.wikipedia.org/wiki/Hyperpyrexia