Dopamine-Responsive Dystonia: An Important Differential Diagnosis to Cerebral Palsy

Introduction: Dopamine-responsive Dystonia (DRD), a rare disease with broad clinical spectrum and genetic heterogeneity, can mimic dyskinetic CP. On average, 13.5 years elapse between the onset of symptoms and the correct diagnosis (Wijemanne et al 2015).

Purpose: To demonstrate the necessity of CSF neurotransmitter analysis in “dyskinetic CP” with normal MRI.

Case Report: A 9-year-old girl, uneventful pre- and perinatal history. In the first year of life, a severe dystonic–spastic movement disorder developed, and “dyskinetic CP” (GMFCS V) was diagnosed. Despite good speech perception, no speech production was possible, but verbal communication could be established with a gaze-controlled computer. Cranial and spinal MRI was normal. Several botulinum toxin injections and orthopedic surgeries were performed. Due to the discrepancy between severe disability and normal MRI, treatment with L-DOPA was started (starting dose 25 mg, leading to psychotic reaction). A reduced dosage (starting with 2.5 mg, then increasing) was tolerated well and lead to an impressive amelioration of the movement disorder and an active speech. CSF analysis (prior to therapy!) revealed low levels of homovanillic acid (HVA), 5-hydroxyindolacetate (5-HIA) and a low HVA/5-HIA ratio. Genetically, two pathogenic mutations in the tyrosine-hydroxylase-gene were found (compound heterozygosity), confirming the diagnosis of an autosomal-recessive dopamine-responsive dystonia.

Conclusion: DRD with mutations in the tyrosine-hydroxylase gene can mimic dyskinetic CP, due to the early onset of symptoms and lack of diurnal fluctuation. CSF analysis for neurotransmitters should be considered in all children with the clinical picture of dyskinetic CP but normal MRI.