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Investigation 

Investigation
Chapter:
Investigation
Author(s):

Ivan Donaldson

, C. David Marsden

, Susanne A. Schneider

, and Kailash P. Bhatia

DOI:
10.1093/med/9780192619112.003.0138
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date: 08 March 2021

In the previous chapter we emphasized the importance of the distinction between primary or idiopathic movement disorders and secondary or symptomatic movement disorders. This distinction is crucial to the planning of investigations in patients presenting with such conditions.

A patient presenting with classical Parkinson’s disease or typical idiopathic torsion dystonia, for example, requires minimal investigation. As a general principle, we would limit investigation of patients with primary movement disorders to imaging of the brain (preferably with magnetic resonance imaging; MRI), exclusion of Wilson’s disease in patients under the age of 50 years, and genetic testing where appropriate. We would also exclude syphilis and record a full blood count and routine biochemistry.

Brain imaging is not essential in every patient with a movement disorder. Thus, an individual with typical Parkinson’s disease or adult-onset writer’s cramp will virtually never be found to have an abnormality on brain computerized tomography (CT) or MRI. It is not cost-effective to image every patient with classical Parkinson’s disease in order to detect the 1 in 4000 who harbour a frontal meningioma presenting with parkinsonism. However, increasing patient expectation, allied to defensive medicine, often dictates the need to image the brain.

Wilson’s disease poses a particular problem, because it can mimic virtually any type of movement disorder. There is a general belief that many patients with Wilson’s disease are not diagnosed early in the course of their illness. Accordingly, it is our practice to screen patients with movement disorders under the age of 50 years for Wilson’s disease, unless a certain diagnosis can be obtained by other means. Measurement of the serum ceruloplasmin and a search for a Kayser–Fleischer ring by slit lamp examination will detect almost all those with neurological Wilson’s disease.

Syphilis is an extremely rare cause of a movement disorder, but again can mimic any neurological condition. Those at risk should also be screened for human immunodefi ciency virus (HIV) infection. Routine blood counts and biochemistry in those with primary movement disorders rarely detect any diagnostic abnormality, but are important base-lines for future management and therapy.

Genetic tests are becoming increasingly important to those managing patients with movement disorders. For instance, the direct genetic test for Huntington’s disease or the DYT1 gene test for idiopathic young-onset dystonia can now provide an unequivocal diagnosis, and obviates the need for further investigation. It is to be expected that there will be increasing numbers of such defi native tests in the future. It is prudent to take blood for extraction of DNA in any patient with a movement disorder that might be inherited. Storage of such samples may prove invaluable in future diagnosis, as new tests become available.

In summary, a patient who clinically appears to have a primary movement disorder, and in whom simple tests are negative, requires no further investigation.

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