Dystonia is involuntary posturing and sustained muscle contractions. When it occurs in a muscle of the face or skull it is called Cranial Dystonia, we often see the involuntary closure of the eyelids or Dystonic Blepharospasm.

It can affect any age. Generalized dystonias are more common in children and focal dystonias in adults. However, we can see generalized dystonia in adults due to brain trauma or lack of oxygen to the brain.

These depend on the muscles affected. If dystonia is in the eyelids, the eyelids will close involuntarily. If it is in the neck muscles, there is often a deviation of the head often accompanied by pain. If dystonia occurs in all body muscles, that is, generalized, as in children, there is a jerking of the head, arms, legs and trunk, that is, a complete inability for the patient. It can also occur in the muscles of the forearm and create a great difficulty to write, which is known as writer's cramp. In addition to other symptoms which will depend on the muscles affected.

They may have a genetic origin, such as generalized in type DYT1 children. They can also be caused by external factors such as head injuries or cerebral hypoxia. However, with focal dystonia the origin is not known. It is associated with brain neurotransmitter disorders.

Generalized dystonia begin in childhood and tend to increase progressively. There is usually great disability in adulthood.

Focal dystonias usually occur in the fourth decade of life onward. Although not disabling, it often creates serious problems in patients, for example: people suffering from laryngeal dystonias have a voice which in many cases makes it impossible for them to communicate.

Dystonia has been known since ancient times. There are medieval paintings where children are seen with abnormal postures reminiscent of generalized dystonia. There were few medical advances in the treatment of this disease, mainly in generalized dystonia. Some historical facts can be identified such as the appearance of botulinum toxin in the treatment of focal dystonias and deep brain stimulation stereotactic surgery of the globus pallidus in generalized dystonia.