Locked-in syndrome is a mercifully rare medical condition in which the patient is totally paralyzed except for the ability to move the eyes. In some cases, the eye movement is restricted to the up and down direction. This state may easily be mistaken for coma, and, very tragically, probably has been. Nevertheless, it is utterly different from coma in that the patient retains full cognitive abilities and consciousness as well as full sensory input. The fully functioning mind is locked within an inert body over which it has no control.
This syndrome is caused by damage to the nerve fibers that carry control instructions from the brain to the muscles of the body (i.e., the downward nerve tracts). The damage occurs in the brain stem, usually near the pons, as the result of traumatic injury, infarction (stroke) or diseases that attack nerve tissue. It is generally irreversible, so there is little hope for significant recovery from this frightful affliction. Stimulative physical therapy may help restore some degree of control over paralyzed muscles, though. Many patients have difficulty breathing, and continued physical therapy is needed to maintain that function. Some patients retain reflex swallowing, but feeding is usually accomplished by tube.
The earliest references to this condition are in literature. A character in The Count of Monte Cristo (1884) was described as "a dead body with living eyes." The first discussion of this disorder in medical literature did not appear until 1941. The first case was diagnosed in 1947. It resulted from cervical spine manipulation by a chiropractor.
The only way LIS patients can communicate is by using eye movements or blinking. Various codes and communication support devices have been developed to aid LIS patients, including computer systems operated by eye movements. There are even serious efforts to link computers directly to the brain via implants. One victim of LIS actually 'wrote' about his condition. Jean Bauby, Editor for Elle magazine, fell victim to LIS at the age of 42. Left only with the ability to blink one eyelid, he wrote Diving Bell and the Butterfly by blinking his left eyelid to pick out letters of the French alphabet one by one as they were read to him.