Brain fever describes a medical condition where a part of the brain becomes inflamed and causes symptoms that present as fever. The terminology is dated, and is encountered most often in Victorian literature, where it typically describes a potentially life-threatening illness brought about by a severe emotional upset. Conditions that may be described as brain fever include:
Encephalitis, an acute inflammation of the brain, commonly caused by a viral infection.
Meningitis, the inflammation of the membranes covering the brain and spinal cord.