Dystonia

What is dystonia?

Dystonia is an incurable neurological movement disorder thought to affect at least 40,000 people in the UK.

The different types of dystonia include:

• Cervical dystonia (spasmodic torticollis) - affects the neck muscles, causing the head to twist, pull in one direction or shake
• Blepharospasm – dystonia of the muscles around the eyes
• Oromandibular dystonia - affecting the muscles of the jaw, tongue and mouth
• Laryngeal dystonia - affecting the speech muscles
• Writer's cramp - affecting the ability to write and sometimes other hand-based tasks

There are several types of dystonia that affect more than one area of the body including generalised dystonia, which affects most of the body, frequently involving the legs and back (trunk).

If dystonia develops in childhood, particularly if it starts in the legs, it may spread to other parts of the body and can become generalised. However, when it develops in adults, it usually confines itself to one part of the body (focal dystonia).

Although dystonia is a neurological disorder, it does not lead to problems with other functions of the brain, such as intellect.

It occurs in all parts of the world and affects people of all ages.

Dystonia causes

The causes of dystonia still aren’t fully understood, but there appears to be a problem in an area of the brain called the basal ganglia, which is involved in controlling movement.

It has been suggested that an imbalance of neurotransmitters, such as dopamine, leads to the defect.

In some cases, damage to the basal ganglia can lead to dystonia. Such cases are referred to as secondary dystonia and possible causes include stroke, a tumour and certain drugs, especially dopamine-blocking drugs used to treat psychiatric disorders.

In the majority of cases, however, no underlying cause is found apart from possible genetic factors. These cases are called primary or idiopathic dystonia.

Genetic risk factors

Dystonia that develops in childhood is often inherited through one or more affected genes.

Most primary segmental or generalised dystonia is inherited in a dominant manner, which means if a parent has this type of dystonia, there’s a 50% chance of passing the dystonia gene to each child.

However, not everyone who inherits the gene develops dystonia, a phenomenon known as reduced penetrance.

Dystonia which develops in adults may also be inherited.

Dystonia symptoms

The progress of dystonia is unpredictable.

The severity of symptoms can vary from day to day, and while there often is an element of overall progression, it is difficult to estimate how long this will last.

Typically, a focal dystonia will progress gradually over a five-year period, and then progress no further.

Symptoms in all dystonic conditions can vary.

For some people, their dystonia may sometimes improve or disappear altogether for no apparent reason.

As with the onset of any long-term medical condition, some people who develop dystonia may go through an initial period of depression, embarrassment and outrage - or relief that there is an explanation for their symptoms.

Dystonia treatments

There is no cure for most forms of dystonia. However, many dystonic conditions can be successfully managed.

Most people manage to develop effective strategies for coping with the challenges their condition brings.

Successful treatments to lessen their symptoms, effective pain control and the acquisition of sensory 'tricks' all help to ameliorate social situations.

Various treatments are available for dystonia. These will be determined depending upon the type and severity of the particular condition.

The main options are:

• Botulinum toxin - injections are generally the most effective treatment for dystonia where it affects the muscles of the neck or around the eyes. However, resistance to botulinum toxin can develop in a minority of patients over time.
• Drugs – some work by interfering with neurotransmitters, the chemical substances that carry messages within the brain, while others are designed to relax the muscles, reducing shaking and control muscle spasms. To be effective, they have to be taken continuously.
• Surgery - may be an option where patients have never been or are no longer receptive to other treatments. Treatments include selective denervation and deep brain stimulation (DBS). In the case of the latter, electrodes are planted in the basal ganglia to help rebalance movement and control posture. Recent research has led to a refinement in the placing of electrodes for optimum effect.

Advice and support

• The Dystonia Society
• Helpline: 0845 458 6322
• Website: www.dystonia.org.uk