A history of oculogyric crises during the encephalitis lethargica pandemic

A pandemic of what came to be known as encephalitis lethargica spread starting in the winter of 1916-1917 and continued into the 1930s. Neurological after-effects, namely permanent parkinsonian syndromes and various abnormal movements, permanently disabled the survivors of the one or two million victims, often children or young adults. Among them, a small proportion developed a symptom that was little known up to that point and that is currently exceptional: oculogyric crises; that is, a lateralised, dystonic upward movement of the eyes known as a tonic eye fit. This paper proposes a history of the recognition of this symptom, its inclusion in the neurological nosography, and the pathophysiological hypotheses postulated a century ago.