Initially dismissed as ‘shell shock’ or psychological trauma, the condition quickly proved to be a physical epidemic. Patients would sit for weeks or months, eyes fixed and bodies immobile, yet they were not truly asleep. Many survivors later recounted the harrowing experience of being fully conscious, hearing and seeing their loved ones, yet unable to move or communicate. This phenomenon shares a haunting parallel with other historical mysteries, such as those explored in The SS Ourang Medan: The Chilling Final Words of a Ghost Ship.

Neurologist Constantin von Economo discovered that the disease was caused by severe inflammation of the thalamus. The illness manifested in two contradictory phases:

• The Stasis Phase: Total physical paralysis and deep, coma-like sleep.
• The Hyper-active Phase: Extreme impulsivity, fits of rage, and insomnia where patients could not stop moving until physical collapse.

For those who survived the initial epidemic, the aftermath was often a life of severe Parkinsonian symptoms, including muscle rigidity and tremors. These patients remained in sanatoriums for decades, a tragedy famously documented by Dr. Oliver Sacks. Their story of sudden, temporary recovery decades later remains one of the most poignant chapters in medical history, reminiscent of the long-term mysteries found in The Soldiers Who Lived in the Ice for 40 Years After WWII.

By 1926, the epidemic receded as quickly as it had arrived, leaving behind no clear cause or cure. Modern researchers now hypothesize that it may have been an autoimmune reaction triggered by a mutated throat bacterium, where the body mistakenly attacked its own brain cells. The sudden disappearance of the disease remains a subject of intense scientific debate, much like other unexplained phenomena such as The Voynich Manuscript: Lost Language or Elaborate Hoax?