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Locked-in syndrome is a condition in which a patient is aware and awake 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 where the eyes are paralyzed, as well. The term for this disorder was coined by Fred Plum and Jerome Posner 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.
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.
Possible causes of locked-in syndrome include:
- Traumatic brain injury
- Diseases of the circulatory system
- Medication overdose
- Damage to nerve cells, particularly destruction of the myelin sheath, caused by disease (e.g. central pontine myelinolysis secondary to rapid correction of hyponatremia)
- A stroke or brain hemorrhage, usually of the basilar artery
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 in combination with eye tracking, may be used to help patients communicate. New direct brain interface mechanisms may provide future remedies. 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
- ↑ Bauer, G. and Gerstenbrand, F. and Rumpl, E. (1979). Varieties of the locked-in syndrome. Journal of Neurology 221 (2): 77–91.
- ↑ Agranoff, Adam B Stroke Motor Impairment. eMedicine. URL accessed on 2007-11-29.
- ↑ 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. Neurology 21 (11): 1140–8.
- ↑ Flügel KA, Fuchs HH, Druschky KF (1977). The "locked-in" syndrome: pseudocoma in thrombosis of the basilar artery (author's trans.). Dtsch. Med. Wochenschr. 102 (13): 465–70.
- ↑ 6.0 6.1 Fager, 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 Communication 22 (3): 222–29.
- ↑ Bruno MA, Schnakers C, Damas F, et al. (October 2009). Locked-in syndrome in children: report of five cases and review of the literature. Pediatr. Neurol. 41 (4): 237–46.
- ↑ lockedinsyndrome at NINDS
- ↑ Parker, I., "Reading Minds," The New Yorker, January 20, 2003, 52–63
- ↑ Berdik, Chris (October 15, 2008), "Turning Thoughts into Words", BU Today, Boston University, http://www.bu.edu/today/2008/10/14/turning-thoughts-words .
- ↑ 'Locked-In' Patients Can Follow Their Noses. Science Mag. URL accessed on 27 Jul 2010.
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