New theory on what killed ancient Greek King Alexander the Great

History books may need to be rewritten after an Otago researcher came up with a new theory on what killed Alexander the Great.

Dunedin School of Medicine senior lecturer Dr Katherine Hall believes the Greek ruler was paralysed.

There's long been debate over what caused the untimely death of Alexander the Great.

Some think the 32-year-old suffered a fever or was poisoned.

But Dr Hall thinks the Macedonian king suffered from Guillain-Barre syndrome.

It's a neurological disorder causing paralysis up the body and could have affected his motor nerves.

"So Alexander could very well have been lying there, unable to move a muscle, and actually still alive because they didn't actually take pulses at that time to determine whether people were dead," she says. 

Colleagues at Otago University studied the case 15 years ago for a BBC documentary suggesting Alexander died from the poison from a white hellebore plant.

But it's always puzzled historians as to why his body didn't decompose for six days.

"My theory actually provides a rationale for why he did not decompose. And that being, that he wasn't actually dead yet," Ms Hall says. 

The ancients took that as proof the great conqueror really was a god.

Dr Hall worked in intensive care for five years and has seen many patients with Guillain-Barre syndrome.

She believes Alexander may have been in a coma, with his breathing almost invisible to observers.

"For one thing, if my theory is correct, the history books should be rewritten actually. Because his date of death should actually be six days later than what is recorded."

A theory she's preparing to defend as the latest chapter in Alexander the Great's fascinating story.