Forms of Dystonia
PRIMARY (Idiopathic Torsion) DYSTONIA
In the majority of cases (known as ‘focal dystonias'), the dystonia only affects one muscle group:Spasmodic Torticollis; the most common of the focal dystonias, involves the neck, the muscle spasms causing the neck to twist to one side (torticollis), forwards (antecollis) or backwards (retrocollis). The neck may pull, turn or jerk; eventually it may be held permanently in one direction.
Blepharospasm is a focal dystonia of the muscles around the eyes. Early symptoms may be uncontrollable blinking, especially in bright light. Sometimes spasms can become so frequent that the eyelids remain tight shut, making the patient unable to see even though the eyes and vision itself are normal.
Oromandibular Dystonia is a focal dystonia of the muscles of the jaw, tongue and mouth. The spasms may cause the mouth to pull open or shut tight. Speech and swallowing may be distorted.
Cranial Dystonia is a combination of blepharospasm and oromandibular dystonia. Other names used to describe the same combination are Meige’s syndrome and Breughel’s syndrome.
Laryngeal Dystonia is a focal dystonia of the speech muscles of the throat causing strained or forced speech (sometimes called spasmodic dysphonia), or inability to speak in more than a whisper (whispering dysphonia). Some patients with cranial dystonia may also have laryngeal dystonia.
Writer’s Cramp is a focal dystonia of the hand in which spasms or contraction of the hand and forearm muscles occur on writing. Other focal dystonias of the hand include typist’s cramp, pianist’s cramp (and other musicians’ cramps), and golfer’s cramp and other sports cramps.
Sometimes the dystonia is more widespread:
Segmental and Generalised Dystonia (Dystonia musculorum deformans). The majority of cases are idiopathic (that is, the cause of the dystonia is unknown) and usually start in childhood in one limb (often the foot). It can spread to involve other parts of the body, including the back, neck and arms.
Dopa-responsive Dystonia (Segawa’s disease). Originally described in Japan, this much rarer condition is also seen in Europe and the U.S.A. Again it usually starts in childhood or adolescence with dystonia and stiffness similar to that seen in Parkinson’s disease, and symptoms often worsen as the day progresses. Treatment with the drug L-Dopa may almost completely relieve the symptoms, and effectiveness appears to last indefinitely.
SECONDARY (“Symptomatic”) DYSTONIA
In this type of dystonia, the symptoms are due to small areas of brain damage. The dystonia is often segmental, generalised, or hemidystonia. The damage can be caused by reduced oxygen around the time of birth (cerebral palsy), by injury to the brain, or by small strokes or tumours. Dystonia can also occur in more widespread nervous system conditions such as Wilson’s disease, encephalitis, and so on.
In some cases dystonia can be caused as a side-effect of treatment with neuroleptic drugs; this is known as tardive dystonia.
Hemifacial Spasm is different from true dystonias in that it seems to result from irritation of the facial nerve. It is a movement disorder that causes the muscles on one side of the face to contract
