Parkinsonism following encephalitis lethargica during the influenza pandemic between 1916 and 1926 is known as postencephalitic parkinsonism (PEP). During the recovery phase of the acute viral encephalitis, parkinsonian rigidity developed with the most characteristic clinical features being oculogyric crises. The PEP brain has NFTs in the cortex, basal ganglia, thalamus, hypothalamus, substantia nigra, brainstem tegmentum, and cerebellar dentate nucleus (48). The distribution of the pathology overlaps with PSP and, in some studies, it has not been possible to distinguish the two disorders by histopathologic analysis alone (48). Biochemical studies of abnormal insoluble tau in PEP have features similar to AD with three major bands (68, 64 and 60 kDa) on western blot studies, and electron microscopy shows paired helical filaments similar to those in AD (49).
Was this article helpful?