Locked-in syndrome is a rare neurological disorder in which there is complete paralysis of all voluntary muscles except for the ones that control the movements of the eyes. Individuals with locked-in syndrome are conscious and awake, but have no ability to produce movements (outside of eye movement) or to speak (aphonia). Cognitive function is usually unaffected. Communication is possible through eye movements or blinking. Locked-in syndrome is caused by damaged to the pons, a part of the brainstem that contains nerve fibers that relay information to other areas of the brain.
The locked-in syndrome may be classified in three different clinical forms, according to the traditional classification of Bauer. This classification is based on the amount of motor outputs, which are preserved in the patients. It talks about a pure form when the patient loses the control of all body movements with the exception of blinking and vertical eye movements; an incomplete form when some voluntary movements other than eye movements are preserved and a total form when a complete loss of motor function occurs. The last condition is particularly dramatic as the patients are completely unable to interact with the environment and to express their needs and thoughts.
Locked-in syndrome is most often caused by damage to a specific part of the brainstem known as the pons. The pons contains important neuronal pathways between the cerebrum, spinal cord and cerebellum. In locked-in syndrome there is an interruption of all the motor fibers running from grey matter in the brain via the spinal cord to the body’s muscles and also damage to the centers in the brainstem important for facial control and speaking.
Treatment should first be aimed at the underlying cause of the disorder. For example, reversal of a basilar artery blood clot (thrombosis) with intraarterial thrombolytic therapy may be attempted up to six hours after symptoms onset. Tumors may be treated with intravenous steroids or radiation.
Affected individuals often need an artificial aid for breathing and will have a tracheotomy (a tube going in the airway via a small hole in the throat) in the beginning.
Feeding and drinking will not be possible via the mouth (it may cause respiratory infection by running into the lungs rather than stomach) and hence will need to be assured via a small tube inserted in the stomach called gastrostomy.
It is important to establish an eye-coded communication as soon as possible. Healthcare providers and family and friends should try to find out what is the easiest code for the affected individual and consequently all use the same code. This can be ‘look up’ for ‘yes’ and ‘look down’ for no or whatever is the easiest movement for the specific case. Communication is then limited to closed yes-no questions and can next be replaced by eye-coded letter spellers such as saying the alphabet and having the affected individual look down to choose her or his letter. There are many variations on this way of communication presenting the letters in frequency of use in the English language (. . . . . . . . . . . . . . . . . . . . . . . . . Z) or using letter boards with different columns and lines for vowels and consonants for example.
Next, treatment should be aimed at the early rehabilitation of the small voluntary movements that remain or recover (often in a finger or foot or swallowing and sound production). Rehabilitation and various supportive therapies are very beneficial and should be started as early as possible even if it needs to be stressed that recovery of near-normal motor control, speaking, swallowing and walking are extremely unusual.
Devices to aid in communication and other assistive technologies have proven beneficial as well as allowing individuals to become active members of society. Infrared eye tracking devices now permit affected individuals to use a computer with artificial voice, control their environment, surf on the internet and send email. In rare cases, some individuals have recovered limited motor abilities, however, in most people such recovery does not occur. Those who recover some motor control in hand or head (as will over half of the patients) can use this to communicate with a computer and sometimes control their wheelchair.
Recent studies and articles in the medical literature have noted that despite significant motor disability affected individuals can retain a good quality of life. In addition, quality of life is unrelated to the degree of physical impairment. With advances in care and assistive technologies, individuals with locked-in syndrome can become productive members of society.