Claim: Stephen Hawking is perfectly healthy
Evidence: Hawking has a rare early-onset , slow-progressing form of amyotrophic lateral sclerosis -LRB- ALS -RRB- that has gradually paralysed him over the decades.
Amyotrophic lateral sclerosis -LRB- ALS -RRB- , also known as Lou Gehrig 's disease and motor neurone disease -LRB- MND -RRB- , is a specific disease that causes the death of neurons which control voluntary muscles.