An autopsy found blood vessels in his brain were extremely hardened, results that have been difficult to understand, said Dr. Philip Mackowiak, who organizes the yearly event.
"Number one, he's so young and number two, he has none of the important risk factors," Mackowiak said.
Lenin didn't smoke - he never let smokers near him. He also didn't have diabetes, wasn't overweight and the autopsy didn't find any evidence of high blood pressure, said Mackowiak, director of the medical care clinical center of the VA Maryland Health Care System, a cosponsor of the event.
There was "considerable suspicion" among Russians at the time of Lenin's death that syphilis was to blame, Mackowiak said.
However, family history appears to have worked more against Lenin, Vinters said.
Lenin was treated for syphilis using the primitive medications available at the time, and while the sexually transmitted disease can cause strokes, there is no evidence from his symptoms or the autopsy that was the case with Lenin, Vinters said.
The Soviet leader's father died at 54, and both may have been predisposed to hardening of the arteries. Stress also is a risk factor for strokes, and there's no question the communist revolutionary was under plenty of that, the neurologist said.
"People were always trying to assassinate him, for example," Vinters said.
Lurie, a St. Petersburg-based expert in Russian history and politics who also spoke at the conference, said that while Lenin had several strokes, he believes Josef Stalin may finished him off with poison, a theory that Vinters said is a possibility.
Lenin's health had been growing worse over time. In 1921, he forgot the words of a major speech and he had to learn to speak again and write with his left hand after one stroke. A major stroke later left him paralyzed on one side and unable to speak.
However, Lurie said Lenin had recovered enough in early 1924 that he celebrated the new year and went hunting. Lenin, who supported Stalin's rise to power, may have realized he made a mistake and began aligning himself with Leon Trotsky, which caused Stalin to poison Lenin, the historian said.
Poisoning, in fact, eventually became one of Stalin's favorite methods of disposing of enemies, Lurie said.
"The funny thing is that the brain of Lenin still is preserved in Moscow, so we can investigate," Lurie said.
Lenin's embalmed body also still lies on public display in a Red Square mausoleum almost 20 years after the collapse of the communist state he helped bring to life.
Vinters, who reviewed autopsy records and the leader's clinical history, said toxicology tests that might have revealed poisoning were not conducted during the autopsy. Reports from the time also show Lenin was active and talking a few hours before his death.
"And then he experienced a series of really, really bad convulsions, which is quite unusual for someone who has a stroke," Vinters said.