Hyperkinetic Movement Disorder: Cervical Dystonia

Dystonia-plus syndromes include dystonia accompanied by other neurologic findings on examination. Dopa-responsive dystonia (DRD), an autosomal dominant condition with incomplete penetrance, is due to a defect in chromosome 14 encoding for the guanosine triphosphate (GTP)-cyclohydrolase enzyme responsible for the biosynthesis of tetrabiopterin, which, in turn, is an essential cofactor in the production of dopamine by tyrosine hydroxylase. Tyrosine hydroxylase is the ratelimiting step in the synthesis of dopamine and other catecholamines. Dopa-responsive dystonia, also known as Segawa disease, typically manifests in the first decade of life as a gait disorder, mimicking cerebral palsy in some patients. In adolescents, the dystonia is characterized by diurnal symptom fluctuations and can be accompanied by mild parkinsonism, tremor, spastic or scissoring gait, and scoliosis. One key feature in the clinical examination of adolescents or young adults with DRD is the marked loss of postural stability noted when performing the pull-push test. The disorder has an excellent response to levodopa, which is the treatment of choice.

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