A neurological condition characterised by involuntary and sustained muscle spasms which can force affected parts of the body into abnormal movements or postures. Dystonia is an umbrella term covering a number of conditions. In most cases, it affects the motor pathways in the brain that control recruitment and movement of muscles causing them to perform an action that leads to unwanted spasms.
Dystonia leads to sustained abnormal postures or repetitive movements of the affected body part. Typically, the abnormal postures are not fixed, and slow writhing movements can occur (athetosis) where the dominant muscle activity switches from agonist to antagonist and back again. Dystonia can affect movement, posture, speech, visual performance and mobility. Living with dystonia can be painful and debilitating, as well as embarrassing and stigmatising. Work, social activities and quality of life may be significantly impacted.
Parts of body affected
In adults, the most common dystonias affect the neck or eyes. Other parts of the body affected include trunk, limbs, hand, voice, mouth and tongue. Adult-onset dystonia is usually focal, affecting one or two parts of the body, while early-onset dystonia often generalises to affect multiple parts of the body.
The experience of pain in dystonia varies between people with dystonia. Some experience extremely intense levels of pain, others experience very little. However, serious levels of pain are reported by large numbers of patients, most commonly in cervical and generalised dystonia, and pain management is an important aspect of treating dystonia.
In the vast majority of cases, dystonia is an organic condition. However, prevalences of depression, anxiety and obsessive-compulsive disorder amongst those with dystonia are often higher than that expected in the general population. The cause of these psychiatric symptoms is thought to be both secondary to the dystonic symptoms and also caused by disruption to normal brain circuitry. Stress and anxiety can also exacerbate the physical symptoms. Neuropsychiatric features are also now recognised in children and young people with some ‘combined’ dystonias such as some types of dystonia-myoclonus.
Causes vary and include gene mutations, brain lesions, premature birth, disorders of body biochemistry known as inborn errors of metabolism, and exposure to drugs or chemicals. Some focal dystonias may arise from repetitive activity leading to over-excitability of the regions of the brain associated with the muscles involved. However, a high proportion of cases have no identifiable cause.
A majority of clinical evidence points to the basal ganglia as the site of pathology in dystonia. However, studies have also identified the cerebellum as playing a causal role.
People with dystonia often require specialists to establish the specific diagnosis, but the hallmarks of dystonia, irrespective of cause, should be identifiable by all health professionals. Depending on the part of the body affected, diagnosis is usually by either a neurologist specialising in movement disorders or another specialist such as an ear, nose and throat surgeon or ophthalmologist.
Dystonia is usually abolished by sleep and returns immediately on waking except sleep can sometimes be interrupted by the pain resulting from dystonia. An exception to this pattern is a rare form called dopa-responsive dystonia in which there may be marked fluctuations in function throughout the day: very good in the morning but worsening during the course of the day, but improved by sleep.
Currently there is no cure but dystonia is very rarely fatal. The condition can be effectively managed with medication, botulinum toxin injections, surgery and other therapies. Spontaneous remissions have been reported in a small minority of cases. There is no cure, but most types of dystonia do not affect lifespan.
Not precisely known, but the Dystonia Society believes that there are at least 70,000 people in the UK affected by dystonia. This equates to a prevalence of 1 in 900. Defazio (2010) suggests that, based on minimum prevalence estimates, idiopathic and inherited dystonias combined should be considered the third most frequent movement disorder after essential tremor and Parkinson’s disease.
The term dystonia was first used to describe childhood torsion disorders by Oppenhiem in 1911. Over the years, the condition has been variously understood as a psychological disorder or as
a pathology of the basal ganglia. Since the mid 1970s and primarily as a result of the work of
Dr David Marsden and Dr Stanley Fahn, there is now a unanimous view that focal and generalised dystonia are organic brain disorders.
Last reviewed April 2014
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