The physicist and author Stephen Hawking became paralyzed due to a motor neuron disease related to amyotrophic lateral sclerosis. Hawking first began to experience the effects of the condition in his early 20s, according to Biography.
Hawking's illness has progressed throughout his life, beginning with difficulties moving and talking and progressing to complete paralysis and the inability to speak, Biography reports. During a visit to Geneva in 1985, Hawking contracted pneumonia, which nearly killed him. A tracheotomy procedure resulted in the complete loss of his speech ability. Hawking initially communicated by raising his eyebrows to select letters from a card, but he eventually began using Equalizer, a computer program that allows him to select from a database of about 2000 words and phrases.