The diagnosis of postencephalitic parkinsonism at the neurological unit of Boston City Hospital, 1930-1981.

The objective of the study is to ascertain the rationale for the diagnosis of postencephalitic parkinsonism (PEP) at Boston City Hospital's Neurological Unit (1930-1981). 5,270 discharge summaries were evaluated for the diagnoses of PEP. Sixteen cases of PEP were identified; the diagnosis of PEP was justified in approximately half of these cases based on the published criteria for distinguishing PEP from Parkinson's disease (PD). In conclusions, the absence of a clear justification for the diagnosis of PEP in many of the 16 cases suggests that the accepted relationship between encephalitis lethargica and PEP may be less definitive than currently believed.