Child Neurology: A young child with an undiagnosed case of dystonia responsive to l-dopa.

Childhood-onset dystonias are a heterogeneously diverse group. There exists a specific set of dystonias that respond profoundly well to low doses of l-dopa (dopa-responsive dystonia [DRD]). Classical DRD is caused by deficiency of GTP cyclohydrolase 1 or tyrosine hydroxylase, but other conditions can cause dystonias that are partially responsive to dopamine. The idea of a diagnostic therapeutic trial with l-dopa for children who present with dystonia has been around for decades and is frequently advocated for; however, l-dopa trials are not without risk.