THE FREQUENCY of papilledema associated with encephalitis varies to some extent from report to report, but usually the condition is described as rare.
This variation is due to several factors. Thus, differences in terminology render comparison and classification of the ophthalmoscopic findings in the various series difficult, and some authors have expressed the view that the presence of papilledema is inconsistent with a diagnosis of encephalitis.
However, the most important reason seems to be that there is a real difference in the frequency of papilledema in the various types of encephalitis. Thus, in epidemic encephalitis (Economo) papilledema is not uncommon,1-3 but considerable differences are seen in the various series reported in the literature. As examples of encephalitides in which papilledema is very rare the following may be mentioned: the Central European type4 and, among etiologically nonclassifiable types, benign myalgic encephalomyelitis,5 and a number of cases reported
PEDERSEN E. Papilledema in Encephalitis. Arch Neurol. 1965;13(4):403–408. doi:10.1001/archneur.1965.00470040069011