VOL: 101, ISSUE: 19, PAGE NO: 50
Shirley A. Grant, RGN, is dystonia nurse practitioner, Ninewells Hospital, Dundee
Peter Meager, MA, BD, CertMgmt, is Scottish coordinator for the Dystonia Society, Cupar
About 40,000 people have dystonia making it the UK’s third most common neurological movement disorder. It is, however, one of the least recognised by the medical profession and the public. Only one-third of those with dystonia in the UK are known to be receiving medical treatment for it. The Dystonia Society’s awareness week - this year 8-14 May - attempts to address this issue.
The week provides an opportunity for information about the illness to be brought before a new generation of nurses who have qualified without encountering it during training. It gives an update on research and treatment developments and also promotes fundraising to aid the Dystonia Society’s research and awareness-raising initiatives.
Classification of dystonia
The most current, widely accepted classification consists of three major categories:
- Bodily site(s) of involvement (anatomical distribution);
- Age at symptom onset;
- Cause or origin.
Dystonia usually begins in a single body part and may remain restricted to that area or spread to involve another region or regions. It is helpful to base classification on anatomical distribution:
- Focal: limited to one area of the body;
- Segmental: affecting two or more nearby or contiguous areas of the body;
- Multifocal: involving two or more distant regions of the body;
- Hemidystonia: affecting one-half of the body;
- Generalised: leg involvement, plus eventual involvement of another region of the body.
Examples of the most common type of dystonia (focal) and common symptoms are shown in Box 1.
The age at symptom onset of primary dystonia is an important indicator of whether it will affect other regions of the body. Generally, the younger the patient at symptom onset the greater likelihood it will gradually affect multiple areas. In contrast, the older the patient at onset the greater likelihood that it will remain localised, potentially with limited involvement of adjacent regions.
Dystonia may be classified based on onset age:
- Childhood onset: 0-12 years;
- Adolescent onset: 13-20 years;
- Adult onset: older than 20 years.
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’.
Dystonia is believed to be due to abnormal functioning of the basal ganglia, which are deep brain structures involved in the control of movement. What goes wrong in the basal ganglia is still unknown. An imbalance of the neurotransmitter dopamine may be an underlying factor in several forms of dystonia, but more research is needed for a better understanding of the mechanisms involved.
Most cases of primary or idiopathic dystonias are believed to be hereditary, occurring because of a faulty gene(s). In these patients, dystonia occurs as a solitary symptom and is not associated with an underlying disorder (MD Virtual University, 2005). Most cases of early onset primary dystonia are due to a mutation in the DYT-1 gene.
Secondary or symptomatic dystonia may occur because of another underlying condition such as Wilson’s disease, multiple sclerosis, stroke, trauma to the brain - by injury during a road accident or oxygen starvation during birth - or as a side-effect of a medication.
There are three main approaches to treating dystonia: oral medications, injections of therapeutic agents directly into dystonic muscle(s) and surgery.
- Benzodiazepines: these drugs interfere with chemical activities in the nervous system and brain, reducing communication between nerve cells. Hence, medications such as diazepam and clonazepam can relax muscles and ease symptoms;
- Baclofen: is used to treat people with spasticity, but it has been administered to some patients with dystonia. Baclofen’s primary site of action is the spinal cord, where it reduces the release of neurotransmitters that stimulate muscle activity;
- Anticholinergics: these drugs block the action of the neurotransmitter acetylcholine, thereby deactivating muscle contractions.
Botulinum toxin is a biological therapeutic agent that acts against dystonia. It is produced by the bacterium Clostridium botulinum. Its use marks a significant advance in the treatment of dystonia.
Injecting the toxin directly into overactive muscles produces controlled, selective and temporary weakness allowing the affected area (for example arm, neck, leg, eyelid) to assume a more normal position or posture (Moore and Naumann, 2003).
A crucial element to successful botulinum toxin injections is that the appropriate muscles are injected, for this reason it is important that the clinician administering the injections be very knowledgeable about the anatomy of the injection site and surrounding areas. The muscular structure of the neck, in particular, is very complicated and the clinician must also be aware of anatomical variation.
Surgery is reserved for the most severe cases that do not respond to medication. Until recently, it tended to be destructive. The aim was to interrupt the pathways that maintained the abnormal muscle movements and involved cutting nerves and muscles or the careful placement of a lesion in the basal ganglia to reduce dystonic movement.
Since 1998, deep brain stimulation surgery has been available at a few hospitals in the UK. An electrode is inserted deep into the brain and connected to a pulse generator that can block the abnormal brain signals responsible for the dystonia.
Another promising procedure is the insertion of an intrathecal baclofen pump. This enables relatively large doses to be given that can control spasms without causing some of the side-effects that would be expected with a similar oral dose.
During the past decade, health care provision within the NHS has been subject to a number of radical changes. The dystonia nurse practitioner was introduced to provide expert specialised care and support to patients, carers and members of the nursing and medical professions.
An additional influence on the development of nurse-led services has been the need to improve patient access to services. The NHS Plan (DoH, 2000) set targets for reducing outpatient waiting lists and reiterated the need for patients to be seen by the most appropriate person at each stage, and to be seen as quickly as possible.
Following the introduction of the specialist nurse and the nurse-led botulinum toxin clinic, patients can be seen more frequently and receive timely and optimal treatment. Greater continuity of care is evident and trust and a good rapport can be built up between nurse and patients. The dystonia nurse practitioner may also perform extended roles, such as injecting the toxin, (a procedure previously only carried out by doctors) provided they have received appropriate training, have the support of their trust and are adequately supervised by a responsible practitioner (NMC, 2002).
In the past 10 years understanding of dystonia has grown considerably. Treatment options have also been expanded and refined, although there is still a long way to go. Moreover, it has become clear that the presence of a nurse practitioner in dystonia clinics can facilitate a holistic service, which is essential to improve patients’ quality of life.
This article has been double-blind peer-reviewed.
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