Introduction
The term locked-in syndrome comes from the English word “locked in” and means to include or lock up. The meaning of the term depends on the situation in which the patient finds himself. He is awake, can understand and follow conversations, but cannot move or speak.
Often only vertical eye movement and closing of the eyelids is possible – the patient is virtually locked in his own body without being able to move. Locked-in syndrome is caused by a very specific brain damage. The clinical picture is accompanied by severe paralysis, which can affect all arbitrarily controllable muscles of the body.
The sensation of touch can remain completely untouched. The Locked-in-Syndrome means an enormous amount of suffering for the patient and also for his relatives. It is in contrast to the apallic syndrome, the so-called waking coma. This is another severe brain injury, but no reactions from the patient to various stimuli are to be expected. The patient is not aware of his environment.
Causes
Locked-in syndrome is caused by damage to the brain stem, more precisely by a defect in the frontal pons (“bridge”). Almost all nerve tracts responsible for controlling voluntary movement run through this area. An exception is the nerve tract that coordinates the vertical eye movements, which is why these are often the only means of communication.
In most cases, the cause of brain damage is the occlusion of a main supply artery of the brain (arteria basilaris), for example during thrombosis. The region is no longer supplied with oxygen by the occlusion, which in the case of nerve cells very quickly leads to cell death. Another possibility is the so-called central pontine myelinolysis.
This involves the death of central parts of the pons, which can be triggered by a severe lack of sodium, for example. However, the deficiency situation itself is not the dangerous thing here, but the therapy. If the deficiency is made up for too quickly, the corresponding reaction occurs. Other causes are extensive damage to the pons through accident-related (traumatic) changes or local inflammatory diseases.
