When dystonia affects only one part of the body, it is called focal dystonia
The Focal Dystonias
These are the most common dystonias and tend to be classified as follows
Cervical dystonia (spasmodic torticollis). This affects the muscles of the neck, causing the head to rotate to one side, to pull down towards the chest, or back, or a combination of these postures
Blepharospasm. This affects the muscles around the eyes. The sufferer experiences rapid blinking of the eyes or even their forced closure causing effective blindness
Oculogyric crisis. An extreme and sustained (usually) upward deviation of the eyes often with convergence causing diplopia. It is frequently associated with backwards and lateral flexion of the neck and either widely opened mouth or jaw clenching. Frequently a result of antiemetics such as the neuroleptics (e.g. prochlorperazine) or metoclopramide
Oromandibular dystonia. This affects the muscles of the jaw and tongue, causes distortions of the mouth and tongue
Spasmodic dysphonia/Laryngeal dystonia. This affects the muscles of the larynx, causing the voice to sound broken or reducing it to a whisper
Focal hand dystonia (also known as writer's/musician's cramp). This affects a single muscle or small group of muscles in the hand. It interferes with activities such as writing or playing a musical instrument by causing involuntary muscular contractions. The condition is "task specific," meaning that it is generally only apparent during certain activities
The combination of blepharospasmodic contractions and oromandibular dystonia is called cranial dystonia or Meige's syndrome
Segmental dystonia affects two or more connected body areas (for example the neck, shoulder, and arm). If two or more areas in different parts of the body are affected, the dystonia is termed multifocal - for example the eyes and vocal cords
Generalized dystonia refers to dystonia that may affect the limbs, trunk, and other major body areas simultaneously. The term axial dystonia describes dystonia that specifically affects the torso
When dystonia only affects muscles on one side of the body, it is calledhemidystonia
Certain dystonias are labeled task-specific which means that the symptoms occur only when the person is performing a specific task or movement. These forms often involve the fingers and hands or the mouth
If symptoms only occur in “episodes” that last for minutes or hours, the terms paroxysmal dystonia and dyskinesias are used
The word torsion is sometimes used, usually in reference to generalized, axial, or segmental dystonia. Torsion refers to the twisting element of dystonia. It describes muscles contracting against each other
