In 1758 Hamilton 1 reported the first case of mumps parotitis with associated central nervous system involvement. At least 21 fatal cases of mumps meningo-encephalitis have been autopsied and reported since then.1-17 Twelve of these cases 6-16 can be designated as secondary (postinfectious) mumps encephalitis which were characterized by the appearance of meningo-encephalitic signs one to three weeks after onset of parotitis and a demyelinating type of central nervous system lesion. Four of these cases 17 can be considered primary mumps encephalitis; these were characterized by signs and symptoms of meningo-encephalitis appearing during or before the development of parotitis. In this group the central nervous system lesion consisted of primary neuron injury (chromatolysis) in the absence of demyelination. The remaining five cases 1-5 of this group can not be classified.
The following case is similar to those reported by Gordon 17 and is considered to be the fifth reported
TAYLOR FB, TORESON WE. Primary Mumps Meningo-Encephalitis. Arch Intern Med. 1963;112(2):216–221. doi:10.1001/archinte.1963.03860020114015