Did FDR Really Have Polio? A Century-Old Medical Mystery Reconsidered

Did Franklin D. Roosevelt really have polio? For most of the twentieth century, the answer seemed settled. Roosevelt’s 1921 paralytic illness was diagnosed as poliomyelitis by leading specialists of the era and permanently disabled his legs. Decades later, however, a widely cited Bayesian analysis argued that Guillain–Barré syndrome (GBS) was more likely. This article revisits that medical mystery using Roosevelt’s surviving clinical records, contemporary epidemiology, and modern neurological knowledge. Several features do support GBS, including his age, ascending weakness, facial involvement, and sensory complaints. But other findings point more strongly toward polio: fever during the evolution of paralysis, preserved objective sensation, highly uneven muscle weakness, focal atrophy and fasciculations, and a lifelong pattern of selective leg paralysis. The influential 2003 statistical argument also counted partly overlapping clinical features separately and did not calculate a single joint probability incorporating the entire case. Although no retrospective diagnosis can be certain, the available evidence supports paralytic poliomyelitis more convincingly than GBS. The controversy illustrates both the appeal—and the limitations—of using modern diagnostic tools to rewrite medical history.