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, sight and mobility but not intellect. 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.
The experience of pain in dystonia varies between patients. 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 dystonia, and pain management is an important aspect of treating dystonia
Parts of body affected
The most common dystonias affect the neck or eye. Others 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. Click here to read about different types of dystonia.
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.
Most of the clinical evidence points to the basal ganglia as the site of pathology in dystonia. The basal ganglia are situated at the base of the forebrain and are associated with a variety of functions, including motor control. (Warner & Bressman 2007).
Cases of dystonia often require specialists to establish the specific diagnosis, but the hallmarks of dystonia, irrespective of cause, are 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. Dystonia often goes unrecognised by healthcare professionals and frequently patients are not diagnosed for many years after symptom onset. GPs and other medical professionals therefore need to be alert to the possible symptoms of dystonia so they can make prompt referrals to the relevant specialist.
Dystonia is usually always abolished by sleep and returns immediately on waking, except a rare form called dopa-resonsive 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.
Rarely fatal but there is currently no cure. However, in many cases it can be effectively managed with medication, surgery and other therapies.
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. At least 8,000 of these are children and young people. Defazio (2010) suggests that, based on minimum prevalence estimates, primary dystonia should be considered the third most frequent movement disorder after essential tremor and Parkinson’s disease.
Dystonia has been known about for over 100 years. For some time it was thought to be of psychiatric origin and patients were given various psychiatric treatments. Only in recent decades has it been recognised as an organic neurological disorder (Warner & Bressman 2007).
Last reviewed October 2011
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