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. 

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 body. Some patients may have the ability to move certain facial muscles, most often some or all of the extraocular eye muscles. Individuals with locked-in syndrome lack coordination between breathing and voice. This restricts them from producing voluntary sounds, even though the vocal cords themselves 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:

There is neither a standard treatment for locked-in syndrome, nor is there a cure, however exceptional cases, like that of Kerry Pink and Kate Allatt have proven that a full spontaneous recovery may be achieved.

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.

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The majority of locked-in syndrome patients may not regain full or partial motor control, but devices are available to help patients communicate. 

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Following is advise from Kate Allatt, who defied all odds and made a remarkable recovery. Nobody is better placed, in my opinion, to give tips than her, so following are the things she has passed on from her experience:

1. Establish with patients whether they understand yes/no questions and are therefore not brain damaged. 

Questions to ask:

 

Parisian journalist Jean-Dominique Bauby suffered a stroke in December 1995, and, when he awoke 20 days later, he found that his body was almost completely paralyzed: he could control only his left eyelid. By blinking this eye, he slowly dictated one alphabetic character at a time and, in so doing, was able over a great deal of time to write his memoir, The Diving Bell and the Butterfly. Three days after it was published in March 1997, Bauby died of pneumonia. The 2007 film The Diving Bell and the Butterfly is a screen adaptation of Bauby's memoir. Jean-Dominique was instrumental in forming the Association du Locked-In Syndrome (ALIS) in France.

In 1966, Julia Tavalaro, then aged 32, suffered two strokes and a brain hemorrhage and was sent to Goldwater Memorial Hospital on Roosevelt Island, New York. For six years, it was believed she was in a vegetative state. In 1972, a family member noticed her trying to smile after she heard a joke. After alerting doctors, a speech therapist, Arlene Kratt, discerned cognizance in her eye movements. Kratt and another therapist, Joyce Sabari, were eventually able to convince doctors that she was in a locked-in state. After learning to communicate with eye blinks in response to letters being pointed to on an alphabet board, she became a poet and author. Eventually, she gained the ability to move her head enough to touch a switch with her cheek, which operated a motorized wheelchair and a computer. She gained national attention in 1995 when the Los Angeles Times published her life story. It was republished by Newsday on Long Island and in other newspapers across the country. She died in 2003 at the age of 68.

Gary Griffin was a veteran of the United States Air Force who became immobile due to amyotrophic lateral sclerosis (ALS, also known as Lou Gehrig's disease and Motor Neurone Disease). He was later equipped with a device called the NeuroSwitch, which allows him to control a computer and communicate with his family. Sensors are attached to the skin over a patient's muscles, and signals are sent to an interface that translates the slightest muscle contractions into usable code.

In 1999, 16-year-old Erik Ramsey suffered a stroke after a car accident that left him in a locked-in state. His story was profiled in an edition of Esquire magazine in 2008. Erik is currently working with doctors to develop a new communication system that uses a computer that, through implants in his brain, reads the electronic signals produced when he thinks certain words and sounds. At present, Erik is only able to communicate short and basic sounds. However, doctors believe that within a few years, Erik will be able to use this system to communicate words and phrases and, eventually, to "talk" normally.

In 1983, Rom Houben survived a near-fatal car crash and was diagnosed as being in a vegetative state. Twenty-three years later, using "modern brain imaging techniques and equipment", doctors revised his diagnosis to locked-in syndrome. He was initially reported as communicating by typing into a keyboard with his right hand,[20] though the presence of a facilitator to move his hand attracted sharp criticism and strong doubts that Houben's communications were authentic.

In early 2010, Dr. Steven Laureys, Houben's neurologist, admitted that subsequent tests had demonstrated that Houben had not actually been communicating via the facilitator, and Der Spiegel, which had originally "quoted" many of Houben's facilitated statements, retracted those quotes as being inauthentic. Laureys maintained that the MRI data that had led him to diagnose Houben as locked-in still suggested that he was conscious.

Houben's case had been thought to call into question the current methods of diagnosing vegetative state and arguments against withholding care from such patients.

In 1993, Graham Miles, originally from Sanderstead, Surrey, suffered a stroke after which he could not move any part of his body except his eyes. His condition improved gradually until in 2010, he could walk with two sticks and drive a car.

In 2010, ex-premiership footballer Gary Parkinson suffered a massive stroke and was later diagnosed with Locked-in Syndrome. This has however not ended his career in football as he is now part of Middlesbrough F.C.'s scouting analysis team, watching potential players on DVD and relaying the verdict to the Middlesbrough manager Tony Mowbray solely through blinking.