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Dystonia
Written by Dr Helen Hanson, Movement Disorders Unit, King's College Hospital, London and Dr K Ray Chaudhuri, Movement Disorders Unit, King's College Hospital, London
Hemifacial spasm
Hemifacial spasm causes muscles on only one side of the face to contract. It affects both men and women and usually develops in middle age. More than 4000 people in the UK are thought to be affected.
Hemifacial spasm develops gradually. Initially the muscles surrounding the eye may be affected by muscle spasms, which continue to spread and affect other muscles on the same side of the face, especially the jaw and mouth. Some patients may experience a clicking sound in the ear on the affected side each time a muscle contracts.
For unknown reasons hemifacial spasm tends to affect the left side of the face more often than the right.
The cause of the spasm may be related to the irritation of the nerve that controls the muscles of facial expression called the facial nerve. This may be due to an abnormally placed blood vessel at the back of the brain, near where the facial nerve arises. So hemifacial spasm may not be truly a dystonia.
Oromandibular dystonia
In this form of dystonia the jaw muscles, lips and tongue are affected causing the jaw to be held open, clamped shut or forced to deviate to one side.
The tongue may be pulled forward, upward, backward or downward.
Sufferers experience problems eating swallowing or speaking. Occasionally, this may be drug induced. Ulceration of the tongue may also occur due to a continuation of dry mouth and tongue twisting.
Orofacial-buccal dystonia
This dystonia is also known as Meiges or Brueghels syndrome. It is a combination of blepharospasm and oromandibular dystonia.
Spasmodic dysphonia
Spasmodic dysphonia (difficulty in voice production) is slightly more common in women than in men and occurs in middle age. The muscles affected are those controlling the vocal cords. Sufferers find that their voice sounds strained and strangled, that it takes a lot of effort to speak and that their voice comes out as tremulous, weak or a breathless whisper.
There are basically two types of spasmodic dysphonia. In the adductor type, speaking causes involuntary excessive muscle contraction of the muscles that bring the vocal cords together. This causes a strained, strangled, choked voice quality, often with abrupt initiation and termination of voicing, resulting in a broken speech pattern. The patient may sound hoarse, breathless, anxious or groaning.
In the abductor type, there is an overcontraction of the muscles that separate the vocal cords, resulting in a choppy and breathy whispering voice pattern.
Spasmodic dysphonia may follow an infection of the respiratory tract, injury to the larynx or a period of excess voice use.
Most patients find that they are able to use their voices normally in some situations. Patients with the adductor type may be able to laugh, whisper or sing normally. Improved speech is noted during emotional or physiological states for example joy, anger or following yawning. Shouting or stress usually makes the condition worse.
Writer's cramp
In this type of dystonia the muscles of the hand and forearm are affected. Contraction or extension of the hand and finger muscles prevents activity or causes an exaggerated posture.
The patient complains of tension and discomfort. They might start to grip the pen too tightly and the script becomes slow and untidy. After a few words the patient is forced to stop and rest. The contraction disappears on stopping writing.
Occasionally the hand dystonia may also be associated with a tremor known as dystonic tremor. Sometimes a primary writing tremor may be mistaken as writing cramp.
Patients often employ trick manoeuvres to overcome the cramp. Some support their writing hand with their opposite arm, use thick nibbed pens, alter their grip or hold the pen in a closed fist. Unfortunately the cramp may arise in the other hand. Patients also find that they begin to have problems with holding other utensils such as forks and knives. Occasionally, the dystonia may be preceded by trauma to the limb.
There are other focal dystonias that are associated with a particular activity or occupation. Examples include typist's cramp, pianist's cramp and golfer's cramp.
Adult-onset primary dystonia
This is a rare subtype of focal dystonia. The symptoms remain localised to the trunk of the body, but may spread to involve the neck muscles. The dystonia does not spread to the leg. Unlike other forms of focal dystonia it is more common in men than women.
The twisting trunk movements have been likened to the Leaning Tower of Pisa, and the term Pisa syndrome is occasionally applied to these dystonias.
'Dystonia-plus' syndromes
Dopamine, (often called 'dopa' which is in fact an intermediate chemical in dopamine's production) is a chemical messenger widely used in the nervous system in passing nerve impulses between nerve cells (neurotransmission). Dopa-responsive dystonia is an important form that can be successfully treated with drugs such as levodopa (eg Madopar, Sinemet). Typically it begins in childhood or adolescence and leads to progressive difficulty in walking and in some cases spasticity (limb stiffness). The symptoms may fluctuate during the day from relative mobility in the morning to increasingly worse disability in the afternoon, evening and after exercise.
This is an important condition to recognise as treatment can result in dramatic improvement in symptoms.
Myoclonic dystonia is a rare type combining dystonia and sudden muscular spasms (myoclonus). The onset is in adolescence or early adult life. It mainly affects the arms and body. These patients can be very sensitive to treatment with alcohol and a genetic basis has been suggested.
Secondary dystonias
Secondary dystonias are often accompanied by other neurological problems. They begin suddenly at rest and are associated with different hereditary and environmental causes. Environmental causes include head trauma, stroke, a tumour, multiple sclerosis, infections in the brain, injury to the spinal cord, or after chemotherapy, drugs or toxins that affect the basal ganglia, thalamus or brain stem.
They may be associated with other hereditary neurological syndromes. Dystonia may be the first sign in a patient with Huntington's disease, and is secondary to many other neurological diseases. These include Parkinson's disease, Wilson's disease and Ataxia telangiectasia. Examples of metabolic disorders causing secondary dystonia are Lesch-Nehan syndrome, Niemann-Pick disease and Leigh's disease. All of these causes are rare.
What drugs can cause dystonia?
Certain drugs have been implicated in causing dystonic reactions or dystonia. This form of dystonia is referred to as secondary or drug induced dystonia. Some drugs may not cause dystonia but may aggravate the pre-existing disorder. Patients should avoid these drugs.
The list of drugs causing drug induced dystonic reactions is long but includes:
In general, alcohol does not have an adverse effect on dystonia but it is rarely seen to hasten it. Alcohol may also help dystonia, particularly forms of myoclonic dystonia. People who chronically abuse alcohol can get a series of involuntary movements or tremors not related to dystonia. Excess alcohol intake is not advised.
Is dystonia hereditary?
It has long been thought that there is a genetic or hereditary link to dystonia, as relatives of patients suffering from dystonia often also have some kind of tremor or dystonia and this link has now been identified in some types of dystonia.
Childhood dystonia (early-onset primary torsion dystonia or dystonia musculorum deformans) is often inherited through one or more affected/mutated genes.
If a parent has this type of dystonia, there is a 50 per cent chance of passing the gene to their children. The gene is on chromosome 9 and known as DYT1. (This mutation has been observed mainly in Ashkenazi Jews.) However, even if the child inherits the gene, they may not necessarily develop dystonia. This is known as reduced penetrance. In the UK about 40 per cent of people with the affected gene develop dystonia.
Research has shown that the gene DYT1 codes for a newly recognised protein called Torsin A. Its function is unknown. However, large amounts are concentrated in an area of the basal ganglia called the substantia nigra pars compacta, suggesting it has a role in dopamine neurotransmission.
Late-onset primary torsion dystonia or focal dystonia is inherited in a more complex manner than the early-onset dystonia. Genes known as DYT6 on chromosome 8 and DYT7 on chromosome 18 may be involved. These genes also have reduced penetrance so only about 12 per cent of people with the affected gene develop the dystonia. DYT6 has been found in people whose neck or head muscles are affected causing problems with neck, speech or facial muscles. DYT7 has been found in those mainly affected with myoclonic torticollis.
Dopa-responsive dystonia also has a genetic basis. Many patients have a mutation in a gene known as GCHI (GTP cyclohydroxylase) on chromosome 14. There is a 50 per cent chance of parents passing on the gene, although with reduced penetrance. However, it occurs more in women. Mutations in this gene cause abnormal production of a chemical called tetrahydrobiopterin, needed to produce the neurotransmitter dopamine. The drug levodopa is helpful in treating this form of dystonia as it increases dopamine levels in the brain.
Myoclonic dystonia also has a genetic component. A mutation in a receptor for the neurotransmitter dopamine has been found on chromosome 11 or 18.
What can my doctor do?
Your GP can refer you to a neurologist who specialises in movement disorders. The neurologist may carry out further investigations. If you are suffering from blepharospasm you may be referred to an ophthalmologist (eye specialist), or if you are suffering from spasmodic dysphonia or oromandibular dystonia you may be referred to an ear, nose and throat (ENT) specialist.
How is dystonia diagnosed?
There is no definitive test for dystonia. Diagnosis depends on the presence of characteristic clinical symptoms and signs. The neurologist will perform a full neurological examination and may also perform blood tests or a brain scan to rule out an illness or injury that may be causing the dystonia. If no cause can be found the dystonia is termed 'idiopathic'.
Is there a cure for dystonia?
Currently there is no cure for dystonia. However, there is a wide range of treatments available. Although these cannot cure the dystonia they will improve the symptoms.
What treatment is available?
Finding the right medication may take some time and patience and trials of several drugs. Not all people respond to the same drug or dosage. If the effects of one drug wear off the replacement with another drug may help.
Side effects include dry mouth, blurred vision, constipation, and difficulty in urinating, memory impairment or confusion.
Benzodiazepines
Baclofen also works by regulating the neurotransmitter GABA. It relaxes skeletal muscle and is particularly good at relaxing muscles which are in spasm. It is relatively free of side effects at low doses. It has a good response in 10 per cent of patients with torticollis.
Dopamine antagonists and agonists
Other drugs that reduce dopamine levels have also helped many people with dystonia. These include phenothiazines, haloperidol, pimozide,
sulpiride and tetrabenazine. However, they can cause side effects including another type of abnormal movements called tardive dyskinesia, possibly with the exception of tetrabenzine. Although these drugs have helped some patients others have reportedly got worse, so they should be used with caution.
Carbamazepine is an anticonvulsant and antiepileptic. It works in a small number of patients and may be of use if other treatments have failed.
Cocktail therapy
Occasionally injection of Baclofen by a pump into the fluid surrounding the brain and spinal cord (cerebrospinal fluid) may be used for severe resistant dystonia or aggravated dystonia known as 'dystonic storm'.
Botulinum toxin
The treatment aims to improve muscle function and dexterity, alleviate pain and correct posture. Focal and well-localised dystonias respond better than segmental or generalised types.
Botulinum neurotoxin type A (Dysport or Botox) is injected into muscles that are painful, tender or visibly contracting. It is also injected into muscles that contribute to the abnormal movement. In very large quantities botulinum can cause fatal paralysis of the respiratory muscles. However, in this treatment it is diluted and injected into specific muscles in very small quantities. It does not come into contact with vital organs such as the liver, kidney or heart. The injections are slightly uncomfortable and painful for several days, but most people find that the symptom relief outweighs the pain.
There are no permanent or persistent side effects. Injections around the neck may produce difficulty in swallowing termed dysphagia, weakness of the neck muscles leading to the head dropping forward and rarely, flu-like illness for a few days. Treating spasmodic dysphonia with injections into the vocal cord muscles may cause temporary softness and breathiness of speech or transient difficulty in swallowing. Injections around the eye may produce drooping of the eyelid or weakness of the eye muscles causing double vision or eye irritation. The side effects usually disappear in a week or so and are unpredictable.
This treatment has been shown to significantly improve dystonia in 75 per cent of patients with spasmodic torticollis. It is also used for the treatment of blepharospasm, writer's cramp, and spasmodic dysphonia, hemifacial spasm and oromandibular dystonia. The rate of success in writer's cramp is less that that of the other focal dystonias with an improvement in about 60 per cent of patients. It is not used in tongue dystonia, as there is an unacceptable rate of adverse affects including problems with swallowing and speaking.
Resistance to the toxin after repeated treatment is rare but about 10 per cent of people will develop antibodies to toxin A (BTA-AB), so treatment becomes ineffective. In some patients the antibodies drop with time, whereas in some people they persist for many years. Removal of these antibodies may be attempted by plasmapheresis (removal of plasma from the blood).
Botulinum toxin type B, C and F are currently under development for those patients who develop antibodies or fail to respond to Type A.
How successful is surgery?
Pallidotomy can be unilateral or bilateral. Firstly an MRI scan is performed to study the anatomy of the brain and basal ganglia. A stereotactic frame, which is a metal jig, is then secured to the patient's head after giving them a local anaesthetic. The frame maps out the areas of the brain for surgery. Under local anaesthetic, a small hole is made in the skull and a probe is inserted. The probe is used to make a lesion in the globus pallidus by applying heat of about 60°C-80°C. The procedure is considered to be safe and have minimal adverse affects.
Studies have shown that most patients do experience a marked improvement in their dystonic movements, although some benefit to a lesser extent.
Another procedure called deep brain stimulation has also been developed to treat dystonia. It is similar to pallidotomy but reversible as the globus pallidus is stimulated rather than destroyed. One study found it resulted in a 65 per cent improvement, which was virtually immediate. The procedure has been shown to be safe with minimal adverse effects.
Advanced generalised dystonias have been helped, if only temporarily, by surgical destruction of parts of the thalamus. The thalamus is a structure deep in the brain that helps to control movement. This operation is called a thalamotomy. It poses a risk of causing speech disturbance as the thalamus lies near the brain structures that help to control speech.
Other operations that can be performed are ones in which the nerves directly to the contracting muscles can be severed. Such procedures are called denervation operations.
Another operation is called microvascular decompression. The theory behind this surgery is that arteries may compress selected nerves and consequently cause dystonic movements. This is a common occurrence in hemifacial spasm where the facial nerve that supplies all the muscles of the face may be compressed by an artery. In the microvascular decompression operation a monitoring procedure ensures that all the blood vessels causing the problem are removed. Abnormal electrical signals from the facial nerve are recorded during the operation, when the last blood vessel is removed the abnormal response disappears. This intra-operative monitoring probably explains why the procedure has a greater than 90 per cent success rate.
Partial sectioning (cutting) and removal (myectomy) of muscles in the neck may also treat cervical (neck) dystonia. Some patients who did not respond to other treatment have undergone sectioning of the trapezius muscle, which is attached between the spine and the shoulder blade. Other patients with congenital muscular torticollis have undergone surgical release of contractive muscle bands or lengthening of the sternocleidomastoid muscle in the neck – the broad muscle that connects the skull behind the ear with the inner end of the collar bone. These operations have been shown to have good long-term benefits.
Other treatment
Good advice
Many patients with focal dystonias such as torticollis can control the abnormal posture for a short time by using sensory tricks or 'gestes antagonistiques'. The most common geste is to place a finger or hand against the lower face on the same or opposite side to the direction of movement. Other gestes include sucking a pen or necklace or pulling on the end of the nose or an earlobe. Ambient sound has also been found to relieve dystonia.
What is the likely outcome?
Focal dystonias are unlikely to spread to become generalised dystonia. However, some focal dystonias may be associated with each other.
If the dystonia develops in childhood then it usually spreads to other parts of the body and becomes generalised. This type of dystonia is much more disabling than the adult focal type.
Support and information
The Dystonia Medical Research Foundation (Canada). Website: www.dystonia-foundation.org.
These drugs regulate the neurotransmitter or chemical messenger GABA (gamma-aminobutyric acid), which helps the brain maintain muscle control. They have sedative, anti-anxiety and anticonvulsant properties as well as muscle relaxing properties. Diazepam, clonazepam, lorazepam and alprazolam are commonly used. The side effects depend on the dose but they may include drowsiness, confusion and light-headedness. They are of used in focal dystonias and help 20 per cent of patients with torticollis.
Drugs such as levodopa (eg Madopar, Sinemet), bromocriptine and amantadine increase dopamine. Dopa-responsive dystonia is remarkably responsive to small doses of levodopa.
In some patients, mostly with severe generalised dystonia, a combination of drugs may be used. This may include benzhexol, baclofen and tetrabenazine, with or without a benzodiazepine.
Botulinum toxin injections have been used in the treatment of dystonia since the early 1980s. Botulinum toxin is produces by the bacterium Clostridium botulinum and is the cause of botulism - an extremely serious form of food poisoning. It is a very potent agent that paralyses muscle by blocking the impulses transmitted to them from nerve endings. However, used under careful medical supervision it can reduce the muscle contractions and the muscles become weaker. However, the nerve endings grow back after about eight weeks, so the treatment needs to be repeated every two to three months.
Surgery is reserved for only the most severe cases that do not respond to medication. Surgery for dystonia is destructive. The aim is to interrupt the pathways that maintain the abnormal muscle movements. It may involve cutting nerves and muscles or the careful placement of a lesion in the basal ganglia of the brain to reduce movement. The operation to damage the area of the basal ganglia called the globus pallidus is called a pallidotomy.
Physical therapies such as physiotherapy with ice, heat or ultrasound, speech therapy for spasmodic dysphonia, acupuncture, osteopathy or chiropractic techniques help some patients. However, treatments involving manipulation of the neck are not recommended for spasmodic torticollis. Relaxation therapies such as hypnosis, behaviour therapy, biofeedback and meditation may also help.
A positive attitude is vital. Dystonia is not life-threatening but can be disabling. Dystonia can have a profound effect both emotionally and functionally. Sufferers should try to continue to lead as normal a life as possible. Counselling and family and social support is helpful.
Focal dystonias such as torticollis and blepharospasm may worsen over several years before stabilising. They may improve or disappear for no apparent reason. The likelihood of this has been estimated from anything from 1 in 10 to 1 in 20, but there is no way to predict whether it will happen. In some cases the dystonia will return after a period of remission, but other patients can remain symptom free for the rest of their lives.
The Dystonia Society, First Floor Camelford House, 89 Albert Embankment, London SE1 7TP. Helpline: 0845 458 6322, Mon-Fri 10am-4pm. Website: www.dystonia.org.uk.
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