"I was about to play the [Funeral] March when, suddenly, I saw emerging from the half-open case of my piano those cursed creatures that had appeared to me on a lugubrious night at the Carthusian monastery. I had to leave for a while in order to recover myself, and after that I continued playing without saying a word."An article by by Sara Reardon points to a paper by radiologist Manuel Vásquez Caruncho of Xeral-Calde Hospital in Lugo, Spain and neurologist Francisco Brañas Fernández that
...draws heavily from descriptions of Chopin's behavior by his friends and pupils and from his own writings. Their vivid recollections report finding the composer late at night, "pale in front of the piano, with wild eyes and his hair on end," unable to recognize them for short periods. He spoke often of a "cohort of phantoms" that haunted him, of seeing his friends as the walking dead, and feeling "like steam."
Only a handful of neurological disorders produce the phantasmagoria that tormented Chopin, who didn't abuse drugs or alcohol. The visions he described, such as demons crawling out of his piano, are now known as Lilliputian hallucinations: detailed visions of people or objects that are much smaller than they are in life. The authors rule out schizophrenia and other common psychoses because Chopin's hallucinations were visual, not auditory, and because he lacked other telltale symptoms such as eye problems or migraines. His short hallucinatory episodes are a hallmark of temporal lobe epilepsy,