Stern’s scientific legacy rests on a conceptual revolution in how physicians understand inflammatory diseases of the brain. When encephalitis lethargica emerged during the First World War, the prevailing framework for classifying brain inflammation followed the tradition established by Hermann Oppenheim and Robert Cassirer in their 1907 monograph, which treated encephalitis as a spectrum disorder to be categorized purely on the basis of clinical symptoms. Stern rejected this holistic approach. Through meticulous clinical observation and, crucially, systematic neuropathological examination of brain tissue, he argued that inflammatory diseases of the central nervous system should be classified as distinct nosological entities defined by their pathogenesis. In doing so, he laid the intellectual foundation for the modern understanding of infectious and inflammatory brain disease, a framework that continues to shape neurology and neuropathology today.

The scale of Stern’s clinical material was extraordinary. His first monograph, published while he was still working in Kiel, described the pathology of the so-called encephalitis lethargica in detail. Two years later, after moving to Göttingen, he summarized the clinical picture in his monograph Die epidemische Encephalitis. A completely revised second edition appeared in 1928, by which time Stern had accumulated clinical experience with more than 800 patients and had performed autopsies on 22 cases spanning both the acute and chronic phases of the disease. This was, at the time, the largest collection of encephalitis lethargica cases ever assembled, and it gave his conclusions an evidentiary weight that few contemporaries could match.

At the heart of Stern’s analysis was a conviction that encephalitis lethargica was caused by a previously unknown virus, an infectious agent that had never been identified. In this he anticipated decades of virological research, although the causative agent of the disease remains unknown even now. Encephalitis lethargica stands as the last pandemic in history for which science ultimately has no clear answer about the responsible pathogen or the exact mechanisms by which the disease produced its devastating neurological sequelae. The epidemic spread worldwide between 1916 and the late 1920s, leaving hundreds of thousands dead and many survivors with profound and often permanent movement disorders, sleep disturbances, and psychiatric symptoms. Stern’s insistence on the infectious origin of the illness placed him firmly on the side of history in terms of disease concept, even as the specific agent eluded him and every researcher since.

Stern’s crowning achievement came in 1936, when his comprehensive chapter on Epidemic Encephalitis, also known as Economo’s Disease, appeared in Bumke and Foerster’s Handbook of Neurology. This work amounted to a full textbook of encephalitis lethargica and represented a milestone in the pathogenetic classification of inflammatory diseases of the central nervous system in general. In it, Stern wrote that the study of encephalitic diseases had undergone a complete revolution thanks to von Economo’s discovery of encephalitis lethargica, and that it was epidemic encephalitis which demonstrated, as he put it, that there is a nosological entity in the field of brain inflammation. The words carried particular poignancy, because by the time they were published, Stern had already been banned from practicing medicine in his own country for three years.

To understand how a leading authority on a pandemic disease could be silenced so completely, one must follow the arc of Stern’s career. Born on April 5, 1884, in Groß Glogau in Lower Silesia, now Glogów in Poland, he grew up in Berlin, where he attended school and studied medicine. He received his doctorate in Freiburg and began his clinical and scientific training as an assistant physician in neurology in Kiel. In 1913, he qualified as a university professor with a thesis on psychiatric disorders associated with brain tumors. In 1920, he accepted an associate professorship and the position of senior physician at the psychiatric clinic in Göttingen, where his most productive scientific years began. But advancement opportunities in Göttingen proved limited and the salary unattractive, so in 1928, at the age of 44, Stern made a fateful decision to move to Kassel, taking up a civil service post as a medical officer in charge of neurology at the medical examination center. He retained his Göttingen professorship and continued to fulfill his teaching obligations, at least during the winter semesters.

The Nazi seizure of power in 1933 destroyed this carefully balanced life almost overnight. Although Stern was a Prussian Protestant, he was of Jewish ancestry, and under the Law for the Restoration of the Professional Civil Service he lost his position as medical officer in Kassel. His teaching license in Göttingen was revoked as well. He moved to Berlin, where he opened a private practice in 1935, and later continued to see patients from his private apartment, which also became a refuge for other members of his family. The man who had written the definitive German-language treatment of a global pandemic was reduced to practicing medicine in hiding, stripped of his academic title, his income, and his professional identity.

Stern fought to escape. As early as 1933, while still in Kassel, he submitted his first application to the Academic Assistance Council, a British-based organization dedicated to finding positions outside Germany for persecuted scientists. Now 49 years old, he sought a clinical or scientific post in the United Kingdom, the United States, or anywhere else that would take him. His applications, preserved in the archives, convey both dignity and a certain desperation. No position could be found for him. He turned next to the Society for the Protection of Science and Learning, the successor organization, but his inquiries there remained equally unsuccessful. The last documented appeal to the society dates from 1939. After that, silence. In 1943, concerned by the absence of any communication, the society’s secretary wrote to colleagues who had emigrated, asking about Stern’s whereabouts. No one could provide any information. Only in 1948 did the American Joint Distribution Committee inform the society that Felix Stern was not among the survivors of the Jewish community of Berlin.

The full truth of his end is devastating in its simplicity. On August 30, 1942, after members of his own family had already been deported by the Nazis, Felix Stern took his own life to escape his imminent deportation. The neurologist who had documented the deaths of hundreds of patients in the greatest encephalitis pandemic of the modern era became, himself, a victim of a man-made catastrophe that no neuropathological classification could capture. His international reputation, which might have offered a lifeline, had lagged behind his German standing for two reasons: the encephalitis lethargica pandemic had already declined by 1936 and was no longer seen as a pressing medical problem, and his work had never been translated into English, leaving his monumental contributions invisible to the scientists and institutions that might otherwise have rescued him.

The rehabilitation of Stern’s memory matters for more than historical justice. His story illustrates how scientific progress depends not only on ideas but on the fragile social conditions that allow scientists to work, communicate, and survive. Stern’s pathogenetic approach to classifying central nervous system inflammation anticipated the way modern neurology distinguishes infectious, autoimmune, and inflammatory brain diseases as distinct entities with distinct mechanisms. That his framework outlived him while his name nearly vanished is a measure of both the durability of good science and the brutality of the forces that interrupted it. As researchers continue to probe the unsolved mystery of encephalitis lethargica, an epidemic whose cause remains unknown a hundred years later, the account of Felix Stern’s life serves as a reminder that behind every nosological category in the textbooks stands a human being, and that the history of medicine is also a history of the lives medicine failed to protect.

Subject of Research: The life and scientific contributions of neurologist Felix Stern, a pioneer in the classification of encephalitis lethargica

Article Title: Felix Stern (1884− 1942)

Article References: Schlegel, J., Stumm, G., Matiasek, K., & Tappe, D. (2026). Felix Stern (1884− 1942). Journal of Neurology, 273(10), Article 606. https://doi.org/10.1007/s00415-026-14141-0

Image Credits: AI Generated

DOI: 10.1007/s00415-026-14141-0

Keywords: Felix Stern, encephalitis lethargica, neurology, Constantin von Economo, history of medicine, pandemic, neuropathology, Nazi persecution, Göttingen, Journal of Neurology, central nervous system inflammation, medical history