Locked-in syndrome (LIS) is a condition in which a patient is aware but cannot move or communicate verbally due to complete paralysis of nearly all voluntary muscles in the body except for the eyes. Total locked-in syndrome is a version of locked-in syndrome wherein the eyes are paralyzed, as well.Fred Plum and Jerome Posner coined the term for this disorder in 1966. Locked-in syndrome is also known as cerebromedullospinal disconnection,de-efferented state, pseudocoma, and ventral pontine syndrome.
Locked-in syndrome usually results in quadriplegia and the inability to speak in otherwise cognitively intact individuals. Those with locked-in syndrome may be able to communicate with others through coded messages by blinking or moving their eyes, which are often not affected by the paralysis. The symptoms are similar to those of sleep paralysis. Patients who have locked-in syndrome are conscious and aware, with no loss of cognitive function. They can sometimes retain proprioception and sensation throughout their bodies. Some patients may have the ability to move certain facial muscles, and most often some or all of the extraocular eye muscles. Individuals with the syndrome lack coordination between breathing and voice. This restricts them from producing voluntary sounds, though the vocal cords are not paralysed.
In children, the most common cause is a stroke of the ventral pons.
Unlike persistent vegetative state, in which the upper portions of the brain are damaged and the lower portions are spared, locked-in syndrome is caused by damage to specific portions of the lower brain and brainstem, with no damage to the upper brain.
Neither a standard treatment nor a cure is available. Stimulation of muscle reflexes with electrodes (NMES) has been known to help patients regain some muscle function. Other courses of treatment are often symptomatic. Assistive computer interface technologies, such as Dasher, combined with eye tracking, may be used to help patients communicate. New direct brain interface mechanisms may provide future remedies; one effort in 2002 allowed a fully locked-in patient to answer yes-or-no questions. Some scientists have reported that they have developed a technique that allows locked-in patients to communicate via sniffing.
Extremely rarely does any significant motor function return. The majority of locked-in syndrome patients do not regain motor control, but devices are available to help patients communicate. Within the first four months after its onset, 90% of those with this condition die. However, some people with the condition continue to live much longer, while in exceptional cases, like that of Kerry Pink and Kate Allatt, a full spontaneous recovery may be achieved.
^Plum; Posner, JB (1966), The diagnosis of stupor and coma, Philadelphia, PA, USA: FA Davis, 197 pp.
^Nordgren RE, Markesbery WR, Fukuda K, Reeves AG (1971). "Seven cases of cerebromedullospinal disconnection: the "locked-in" syndrome". Neurology21 (11): 1140–8. doi:10.1212/wnl.21.11.1140. PMID5166219.
^Flügel KA, Fuchs HH, Druschky KF (1977). "The "locked-in" syndrome: pseudocoma in thrombosis of the basilar artery (author's trans.)". Dtsch. Med. Wochenschr. (in German) 102 (13): 465–70. doi:10.1055/s-0028-1104912. PMID844425.
^ abFager, Susan; Beukelman, Karantounis, Jakobs (2006). "Use of safe-laser access technology to increase head movements in persons with severe motor impairments: a series of case reports". Augmentative and Alternative Communication22 (3): 222–29. doi:10.1080/07434610600650318. PMID17114165.Cite uses deprecated parameters (help)
^For therapeutic dose of tubocurarine by shorter limit as given at page 151 in: Rang, H. P. (2003). Pharmacology. Edinburgh: Churchill Livingstone. ISBN0-443-07145-4. OCLC51622037.
^For 20-fold paralytic dose of toxiferine ("calebas curare"), according to: Page 330 in: The Alkaloids: v. 1: A Review of Chemical Literature (Specialist Periodical Reports). Cambridge, Eng: Royal Society of Chemistry. 1971. ISBN0-85186-257-8.