Similar to managing Parkinson's Disease patients with psychotic symptoms, treating both dopa-responsive dystonia and psychosis is difficult because the treatments for these conditions have counteracting mechanisms of actions.
It is necessary to start the antipsychotic at a low dose and slowly titrate up, as starting at a higher dosage or titrating too quickly can potentially exacerbate motor symptoms of dopa-responsive dystonia. Therapeutic effect was eventually reached at 2 mg daily.
The biggest limitation of this case was the lack of genetics testing to confirm his diagnosis of dopa-responsive dystonia. With the patient's permission, we had obtained previous medical records from the children's hospital in which he was diagnosed with dopa-responsive dystonia.
In conclusion, this case demonstrates that risperidone is effective in managing psychotic symptoms in a patient with dopa-responsive dystonia. This case also brings up the question on whether psychosis is a late manifestation of dopa-responsive dystonia.
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 Nonstandard abbreviations: B[H.sub.4], tetrahydrobiopterin; GTPCH, GTP cyclohydrolase 1; IFN-[gamma], interferon-[gamma]; TNF-[alpha], tumor necrosis factor-[alpha]; PTPS, 6-pyruvoyltetrahydropterin synthase; SR, sepiapterin reductase; DHPR, dihydropteridine reductase; DRD, Dopa-responsive dystonia; and CSF, cerebrospinal fluid.