Aim: A large number of patients with encephalitis lethargica developed different post-encephalitic syndromes (PES), which have an important medical and social impact. We studied the clinical and historical aspects of PES in Spain by reviewing the medical literature published in this country between 1918 and 1936.
Development: There are no statistical data concerning PES in Spain, although Spanish physicians drew attention to their high rate of prevalence and their repercussions on community health. Most of the 140 patients that were reviewed (74%) presented predominant Parkinsonism, but some features of Parkinsonism were observed in nearly all cases. Other movement disorders (focal dystonias, chorea, myoclonus, oculogyric crises, abnormalities affecting breathing rate) were described, as well as sleep, endocrine and vegetative disorders. Psychiatric disorders were often reported, the most frequent being bradyphrenia associated to Parkinsonism, but a hypomanic picture with impulsive behaviour was very characteristic among young people. PES was diagnosed on average two years after the episode of acute encephalitis lethargica, although it often appeared immediately afterwards. Many studies discuss the contribution made by PES to further our knowledge of the pathophysiology of extrapyramidal diseases and about the involvement of the basal ganglia in psychiatric and behavioural disorders.
Conclusions: Despite the absence of statistical data, Spanish authors highlighted the important repercussions the PES had on community health, as well as the role they played in extending our knowledge of the pathophysiology of the basal ganglia. Cases of Parkinsonism were predominant, although all kinds of post-encephalitic manifestations were reported.