During periods of increased incidence of endemic virus infections, I have observed a number of patients who, after the acute stage of infection had passed and the temperature had returned to normal, complained of prostration with general fatigue and increased fatigability, mental depression, and symptoms of peripheral mononeuritis or polyneuritis. Among them, a group of 22 cases was found to show a pupillary syndrome of alternating contraction anisocoria. This syndrome indicates involvement of the anterior midbrain and characterizes the condition as virus encephalomyelitis.1
The patients were neurologically examined an average of six weeks after the onset of the disease. The infection itself was usually described as having started with a sudden rise in temperature. The temperature did not rise to more than 102 F in any of our cases, and in seven cases the rise was not expressly reported but on analysis of the history appeared to have occurred.
LOWENSTEIN O. Benign Postinfectious Disorder of Anterior MidbrainAlternating Contraction Anisocoria, Combined with General Fatigue and Peripheral Neuritis. AMA Arch NeurPsych. 1955;73(3):302–308. doi:10.1001/archneurpsyc.1955.02330090048005