Stephen Hawking may have been misdiagnosed and actually a victim of polio, a US medical expert has suggested.
Christopher B Cooper, Professor Emeritus of Medicine and Physiology at the University of California, Los Angeles, said the probability the physicist's famously debilitating condition was in fact amyotrophic lateral sclerosis (ALS) was "low".
He said Hawking's relatively young age of diagnosis, 21, and his 55-year period of survival does "not match our understanding of ALS".
In a letter to the Financial Times, the medic argued it is more likely Hawking's neurological and motor system impairment was caused by poliomylitis, of which there was epidemics in both America and Europe in 1916 and 1952.
"Perhaps Hawking was unlucky to contract poliomyelitis or a similar viral infection a few years later in 1963," he said.