Diagnostic process


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Dystonia can be difficult to diagnose because of its variability in presentation, wide spectrum of causes and coexistence with other movement disorders. Diagnosis is based on clinical presentation. The core manifestation is abnormal postures and involuntary muscle spasms (with or without tremor) and the recognition of specific features e.g. ‘geste antagoniste’, overflow and mirror movements. It is also a case of eliminating other conditions.

The use of a structured flow chart such as shown in Figure 1 may help diagnostic accuracy:

Diagnosis

It is important to be aware that some psychogenic disorders have symptoms which can appear similar to dystonia and these need to be eliminated.

Dystonic symptoms can sometimes temporarily disappear when the patient is concentrating and, for this reason, dystonia is sometimes missed even by experienced neurologists. Helpful techniques to aid diagnosis can include:

  • Asking the patient to sit in silence for several minutes (for blepharospasm).
  • Where cervical dystonia is suspected, asking them to close their eyes
  • Giving the patients a biscuit to check for oromandibular dystonia.

Because the symptoms of dystonia are diverse, patients may not realise that symptoms in different areas of the body are part of the same underlying condition and so fail to report some relevant symptoms. Where dystonia is suspected, it is therefore important to ask about symptoms in all the main body areas affected by dystonia.

Assessment of dystonia may be performed using a validated rating scale (eg. Burke-Fahn-Marsden Dystonia Rating Scale, TWSTRS, CDIP-58). They are most useful for measuring the effectiveness of certain treatments such as deep brain stimulation.

Additional tests

Structural brain imaging (MRI) is required in generalised or hemidystonia and if there are any features to suggest an acquired form of dystonia. However, MRI is not routinely required when there is a confident diagnosis of idiopathic (or inherited) focal dystonia in adult patients, as this is almost always a normal study.

Neurophysiological tests are not routinely recommended for the diagnosis or classification of dystonia.

Other tests can be carried out but may not be routinely used unless diagnosis is proving difficult or in the case of rarer conditions; these may also be used where other members of the family may also be affected. These can include those recommended by Albanese et al 2006 & 2010, for instance:    

  • Pre-synaptic dopaminergic scan can be useful to differentiate between dopa-responsive dystonia (DRD) and juvenile Parkinson’s disease. This can also be useful to distinguish dystonic tremor from parkinsonian tremor.   
  • Appropriate investigations are required if the initial presentation or the course of the symptoms suggest presence of degenerative or structural pathology or acquired symptomatic dystonia.
  • Testing of DYT1 gene in individuals with young onset dystonia can prevent the need for other more invasive tests.
  • Testing of family members of an index case with DYT1 dystonia should only be done with appropriate genetic counselling.
  • DYT6 testing can be helpful in early-onset dystonia or familial dystonia with cranio-cervical predominance.   
  • Individuals with early-onset myoclonus dystonia affecting the arms, neck or trunk, particularly if positive for autosomal-dominant inheritance, may lead to testing for the DYT11 gene.

Testing for the PNKD gene (DYT8) can be helpful in symptomatic individuals with PNKD.

Diagnosis of children

The diagnosis of dystonia in children can be difficult and, as with adults, it is most often a case of eliminating other conditions. For this reason a comprehensive holistic history and assessment of the child and the family must take place so that an accurate diagnosis can be made. Parents should be kept well-informed and supported throughout this process.

Nevertheless, even in specialist hands, establishing a genetic diagnosis may represent ‘work in progress’ as large referral centres discover new gene mutations. This process of exact diagnostic characterisation often requires collaboration of several centres and can take many years. New technologies are simplifying and reducing the costs of these searches. Screening multiple dystonic conditions with a single blood test will certainly shorten the length of time required to obtain definitive diagnoses and also identify cases that require fresh searches for as yet uncharacterised genetic causes.

A lack of genetic diagnosis may prevent appropriate counselling regarding future affected children but also affects decisions about management since the ‘genetic dystonias’ tend to respond more favourably to deep brain stimulation (see below). Cheaper and faster diagnostic pathways are therefore needed for children’s dystonia services.

Giving a diagnosis

Many patients receiving a diagnosis will know little if anything about dystonia. Sufficient time
should be allowed during the consultation for a careful explanation. The patient’s key concerns
are likely to include:    

  • An explanation of the condition and its prognosis
  • Management options – including timing and location.
  • Additional sources of information – including details of the Dystonia Society helpline and website.

Additional sources of support:

  • The Dystonia Society can supply relevant leaflets to clinics to aid this process.
  • An important new source of information is online peer support groups using forums or Facebook pages. These can link people with dystonia, parents and carers together – but users need to be advised that they are usually moderated by unpaid volunteers and non-professionals. The Dystonia Society can provide information as to what online peer support  options are available.

Last reviewed April 2014

Disclaimer
The Dystonia Society provides the information on this page as general information only. It is not intended to provide instruction and you should not rely on this information to determine diagnosis, prognosis or a course of treatment. It should not be used in place of a professional consultation with a doctor.
The Dystonia Society is not responsible for the consequences of your decisions resulting from the use of this information, including, but not limited to, your choosing to seek or not to seek professional medical care, or from choosing or not choosing specific treatment based on the information. You should not disregard the advice of your physician or other qualified health care provider because of any information you receive from us. If you have any health care questions, please consult the relevant medical practitioner.