How Many types of 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

Primary dystonias

Generalised dystonia

This is also known as primary torsion dystonia or dystonia musculorum deformans. The usual age of onset is between 5 and 16 years. Parents or teachers may notice an abnormal turning in of the foot, an awkward gait or contractions of many different muscle groups.

The involuntary dystonic movements may progress quickly to involve all the limbs and torso, but the rate of progression usually slows after adolescence.

A genetic basis for generalised dystonia has now been confirmed.

Focal dystonias

Spasmodic torticollis

Torticollis, commonly called wry neck, is the condition of spasm affecting the muscles of the neck, causing the head to assume unnatural postures or turn uncontrollably.

Spasmodic torticollis, also known as cervical dystonia, is the most common of the focal dystonias. There are thought to be 10,000 people in the UK suffering from this condition.. The average age of onset is in the early 40s and more women are affected than men.

The head may tilt (laterocollis) or twist to one side (rotational torticollis), forward (anterocollis) or backward (retrocollis). The movements may be sustained or jerky (myoclonic torticollis). Muscle spasms or pinching nerves in the neck can be very painful. The neck may eventually be held permanently in one position.

Torticollis usually develops gradually. At first, the patient may notice that the head turns during everyday activities. In about a quarter of patients the hand may also develop some tremor, especially if trying to correct the involuntary movement. The tremor is common but not usually disabling and is referred to as an enhanced physiologic tremor.

The severity of torticollis can vary and may be worse if the patient is under stress. Occasionally drinking alcohol can improve the torticollis.

Some sufferers have a history of head or neck injury, but as yet there is no evidence to support the theory that torticollis is directly related to trauma.

Most patients find the condition deteriorates over the first five years, but their symptoms then stabilise. One third of patients progress to a segmental dystonia, usually involving the arm. The symptoms of about 10 per cent may stop spontaneously, but then later recur.

Patients with torticollis often find that their daily lives are affected. Head turning can prevent a proper view of the road when driving, it may become difficult to eat, brush teeth or apply makeup. Many sufferers find embarrassment and anxiety the major handicap.

Blepharospasm

Blepharospasm means the involuntary contraction of the eyelids, leading to uncontrollable blinking and closure of the eyelids.

It affects more women than men and in the UK and it is the second most common focal dystonia with approximately 4000 people affected. In very extreme cases, sufferers are unable to prevent their eyes from clamping shut so that despite normal vision they are functionally blind.

Muscles in the face can also become affected causing facial distortions and grimacing when the patient attempts to open her eyes.

Blepharospasm usually develops gradually. The first sign a sufferer may notice is eye irritation and discomfort, light sensitivity and increased blinking. They may find that the condition worsens when they are tired, under stress or reading. Bright flickering lights, smoke or wind can all irritate the condition making symptoms worse.

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:

• antidepressants (amitriptyline, Amoxapine (Asendis), bupropion, clomipramine (eg Anafranil), doxepin (eg Sinequan), fluoxetine (eg Prozac), imipramine, nortriptyline (Allegron), trimipramine (Surmontil) and trazodone (eg Molipaxin)).
• anti-anxiety agents (alprazolam (Xanax), buspirone (eg Buspar))
• anti-nausea/vomiting agents (metoclopramide (eg Maxolon), prochlorperazine (eg Stemetil)).
• neuroleptics (chlorpromazine (eg Largactil), clozapine (eg Clozaril), fluphenazine (eg Moditen), haloperidol (eg Haldol), perphenazine (Fentazin), promazine, trifluoperazine (eg Stelazine)). The dystonia associated with neuroleptics is often called tardive dystonia.
• other drugs include the psychiatric drug lithium (eg Priadel), midazolam used in anaesthetics, phenytoin (eg Epanutin) an anticonvulsant, promethazine (eg Phenergan) an anti-allergy drug and verapamil (eg Securon) an antihypertensive.

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.

See more, you could visit http://www.netdoctor.co.uk/diseases/facts/dystonia.htm