Diagnosing Dystonia

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DIAGNOSIS — The diagnosis of dystonia is based mainly upon clinical features, although the diagnostic laboratory can provide supportive evidence. In the absence of specific diagnostic tests, expert observation by a movement disorder specialist is suggested to confirm the diagnosis of dystonia in cases where there is uncertainty or confusion. Now, who's confusion ???

Primary dystonia is separated from secondary dystonia by the absence of additional neurologic abnormalities and the lack of possible acquired cause such as the use or exposure to reglan or other medications.

As noted earlier, the age and anatomic distribution of dystonia at onset are important clinical clues for diagnosis. Atypical presentations (eg, a child with onset of dystonia in the neck or face, or an adult with onset in the leg, or an adult who develops generalized dystonia) indicate the need to evaluate for an underlying cause.

Laboratory testing in primary dystonia is of minimal usefulness, but essential in the evaluation of secondary dystonia, or dystonia with atypical features.

Levodopa trial — Patients with focal or generalized dystonia of unknown etiology should have a trial of levodopa (eg, carbidopa-levodopa 25/100 mg three times daily) to confirm or exclude the diagnosis of dopa-responsive dystonia. This is DRD and why you are placed on a trial of it. It either works or doesnt in a matter of weeks, resolving symptoms.

Genetic testing — In patients with early onset dystonia, or those with late onset who have an affected relative with early onset dystonia, DYT1 gene testing is indicated with appropriate genetic counseling.

Molecular genetic testing is possible but NOT widely available for dopa-responsive dystonia (DYT5), myoclonus-dystonia (DYT11), rapid-onset dystonia-parkinsonism (DYT12), and deafness-dystonia-optic neuronopathy syndrome .

Laboratory evaluation — The assessment of atypical and/or secondary dystonia is extensive . Laboratory evaluations and brain imaging should be obtained and appropriately directed. When there is clinical suspicion for secondary or heredodegenerative dystonia, we suggest obtaining the following studies:

• CT or MRI of brain (basal ganglia calcifications or necrosis and other abnormalities)
• Complete blood count
• Electrolytes
• Renal and liver function tests
• Antinuclear antibodies
• Ceruloplasmin, serum copper, and 24-hour urinary copper (for Wilson disease)
• Erythrocyte sedimentation rate
• Rapid plasma reagent