What is dystonia?
Dystonia is a neurological condition. The main symptoms are involuntary prolonged muscle spasms experienced as painful, repetitive movements and postures which can be painful. The movements are caused by abnormal function of the motor pathways in the central nervous system. Abnormal muscle movements are the main symptom and the cause of disability in the condition. The abnormal movements are not under conscious control and usually persist for life. Dystonias are rare; abnormal movements are very visible, the fact that movements are uncontrollable can be difficult for unaffected people to understand, the condition may often be perceived as psychological.
The name of the condition is given depending upon which muscles are affected.
Dystonia affecting only one area of the body is called ‘focal’ dystonia.
For example dystonia affecting the neck muscles is a focal dystonia called cervical dystonia or ‘spasmodic torticollis’, dystonia affecting the muscles around the eyes is called ‘blepharospasm’. A proportion of people with focal dystonia will develop another dystonia in a nearby area of the body – it is fairly common for people with blepharospasm over time to develop a dystonia of the muscles around the mouth as well. When two adjacent areas of the body are affected this is called ‘segmental’ dystonia.
Focal dystonia most often begins in middle age and usually remains focal. The legs and walking ability are rarely affected. In most cases dystonia is ‘idiopathic’ – of unknown cause, also called ‘primary’ dystonia. Most people with dystonia will have worsening symptoms for some time after onset. The condition will then stabilise and in general will not get worse. Most people reach this point within 5 years of onset.
Dystonia can be caused by drugs particularly neuroleptic drugs used to treat psychiatric conditions and long term use of some anti-emetic drugs such as metoclopramide – these drugs typically cause the movement disorder ‘tardive dyskinesia’ but can also cause “tardive dystonia”.
Dystonia affecting many areas of the body is called ‘generalised’ dystonia.
It is clinically defined as dystonia affecting-:
- One or both legs
- The trunk and one other body part such as an arm or neck.
Generalised dystonia commonly begins in childhood. It can be a primary condition (this includes those caused by certain identifiable gene defects) or a secondary condition. In secondary dystonia there is another underlying condition causing the dystonia. In childhood onset generalised dystonia, a significant proportion are secondary and are caused by other conditions including metabolic and structural diseases. Generalised dystonia can cause severe disability.
In this guidance the focal dystonias are described individually in the first section, generalised dystonias in the second section and rare dystonias in the final section.
This guidance covers the following conditions
Focal dystonias:
- Blepharospasm abnormal excessive or frequent blinking with or without grimacing and or prolonged closure of the eyes, due to spasm of the muscles around the eyes (orbicularis oculi). Affects vision.
- Oromandibular dystonia (cranial dystonia) – abnormal movements of the muscles of the jaw, lips and tongue. May involve jaw grinding or holding the mouth open. Affects eating, swallowing and speech.
- Spasmodic dysphonia/laryngeal dystonia– affects the muscles controlling the vocal cords. Speech may be forced or strained or whispering. Affects ability to communicate.
- Spasmodic torticollis or cervical dystonia – affects the muscles of the neck – causing abnormal head movements, tremor or spasm. May be very painful and can affect posture and movement particularly walking in severe cases.
- Hemifacial spasm – only one side of the face is affected by abnormal movements, this ranges from some abnormal movements to disfigurement of the face that may affect vision on one side.
- Dystonic Writer’s cramp – focal hand dystonia – affects the hand and finger muscles when attempting to write or do other similar manual activities such as using a screw driver or knife. Cramping may be painful. Dexterity may be severely impaired. The other side may also be affected. Other task specific upper limb dystonias include dystonic typist’s cramp, musician’s dystonia and golfer’s yips.
- Cranial dystonia – this term is used to describe any dystonia affecting muscles of the head and face, this may include any of the following: blepharospasm, oromandibular dystonia, lingual (tongue) dystonia.
Generalised dystonias
This condition affects many areas of the body, the legs may be affected and walking may be difficult or impossible. There is more than one type of this condition and disability may be severe.
Rare dystonias
- Paroxysmal dystonia – this type of dystonia is not present all the time but occurs in unpredictable attacks. These may be rare or many times a day. Attacks will involve uncontrollable movements of parts of the body without loss or alteration of consciousness or confusion. The attacks may last from a few seconds to several hours and can be painful and exhausting. Movement is normal in-between attacks with no evidence of dystonia. It is very rare.
- Myoclonus dystonia – Myoclonus refers to sudden involuntary ‘shock-like’ muscular contractions. These contractions usually affect the arms, shoulders, neck or trunk. The sudden movements are called ‘myoclonic jerks’. Onset is usually in childhood or adolescence; other dystonic movements may develop later in life. The frequency of jerks stabilises within a few years.
- Tardive dystonia – this type of dystonia is a drug side effect and develops most commonly in younger people taking dopamine receptor blocking drugs for months or years. The condition can resolve if the causative drug is stopped at the onset of symptoms. The longer the drug is continued the more likely the dystonia will be permanent. The main symptoms are strong uncontrollable muscle spasms in the trunk, neck, arm and leg muscles.
- Tardive dyskinesia - this type of movement disorder is a drug side effect and develops most commonly in older people taking dopamine receptor blocking drugs for months or years. The condition can resolve if the causative drug is stopped at the onset of symptoms. The longer the drug is continued the more likely the disorder will be permanent. The main symptoms are ‘fidgety’ rhythmic type movements of the facial muscles, grimacing and lip smacking. Movements may be constant, the condition is disfiguring.
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Amended May 2009
