The deaths of many notorious figures are shrouded in mystery. Lenin's was no different. Vladimir Ilich Ulyanov, who later changed his name to Vladimir Lenin, ushered in the era of Soviet communism that ruled until the dissolution of the Soviet state in 1991. Yet, the presumptively healthy Lenin didn't last long in power. He died just before his 54th birthday of a massive stroke and, possibly, poison.

Hoping to resolve Lenin's cause of death, two scientists recently pored over his medical history. Lenin's health troubles began when he nearly died from an assassination attempt in 1918. He was shot twice, with neither bullet removed. Four years later, he suffered the first of three debilitating strokes. The last, a massive stroke, occurred January 21, 1924, and he was dead within hours.

What brought on these strokes? An autopsy at the time revealed almost complete blockage of the arteries to the brain. But Lenin did not have the usual risk factors such as high blood pressure, diabetes, obesity, smoking or drinking. He also had extremely hardened blood vessels in his brain which suggested a syphilis infection, but autopsy records show that's unlikely.

What is clear is that genetics played a big role. Lenin's father died at 54 from cerebral hemorrhage. Three siblings had cardiovascular disease. However, this does not explain Lenin's seizures hours before his death.

Seizures aren't associated with strokes, but can be brought on by poison. At the time, Russia was a place of great political intrigue and Joseph Stalin was vying for control. Starting in 1921, Lenin began suffering problems such as insomnia and severe headaches. Historians speculate Stalin poisoned him with cyanide. But it is unclear whether that contributed to his death.

Lenin's embalmed body is on display in Moscow. While a brain tissue sample might reveal whether he'd been poisoned, it is not likely to happen.