Secondary Parkinsonism in Childhood: A Rare Complication After Radiotherapy

Secondary parkinsonism is uncommon in children and exceedingly rare after cranial radiotherapy. This report describes a 14-year-old female who presented with growth retardation as a result of a craniopharyngioma, which was partially resected. A secondary hydrocephalus responded well to shunting. She gradually developed a severe hypokinetic-rigid syndrome 6 months after radiotherapy (54 Gray in 30 daily fractions of 1.8 Gray). In addition, her vigilance decreased. Magnetic resonance imaging revealed increased signal intensity on T₂-weighted images in the globus pallidus bilaterally. Nuclear scans indicated only a marginal striatal dopaminergic deficit and revealed decreased metabolism in the thalamus bilaterally. Treatment with dopamine agonists resulted in minor improvement in motor function. Magnetic resonance imaging investigations 3 months later disclosed a decrease of signal intensity changes of the globus pallidus. Gradually, bradykinesia diminished slightly and vigilance increased little. In conclusion, secondary and partially reversible parkinsonism can occur in children after radiotherapy. We suggest that focal encephalopathy resulting from postradiation edema secondary to microangiopathy led to dysfunction of the globus pallidus and thalamus.