Movement Disorders I: Tics and Stereotypies

Abstract

1. Samuel H. Zinner, MD* 2. Jonathan W. Mink, MD, PhD† 1. *Associate Professor of Pediatrics, University of Washington School of Medicine and Seattle Children's Hospital, Seattle, Wash. 2. †Professor of Neurology, Neurobiology, & Anatomy, Brain & Cognitive Sciences, and Pediatrics, University of Rochester School of Medicine and Dentistry and Golisano Children's Hospital at Strong, Rochester, NY. After completing this article, readers should be able to: 1. Identify the important features of tics and stereotypies. 2. Recognize comorbid conditions and overlapping qualities with tics. 3. Describe treatment approaches for tic disorders. Movement disorders involve impairment of appropriate targeting and velocity of voluntary movements, dysfunction of posture, the presence of abnormal involuntary movements, or the performance of normal-appearing movements at inappropriate or unintended times. The abnormalities of movement are not due to weakness or abnormal muscle tone but may be accompanied by weakness or abnormal tone. By convention, movement disorders are divided into two major categories. The first category is hyperkinetic movement disorders, sometimes referred to as dyskinesias. This term refers to abnormal, repetitive involuntary movements and includes most of the childhood movement disorders, including tics, stereotypies, chorea, dystonia, myoclonus, and tremor. The second category is hypokinetic movement disorders, sometimes referred to as akinetic/rigid disorders. The primary movement disorder in this category is parkinsonism, manifesting primarily in adulthood as Parkinson disease or one of many forms of secondary parkinsonism. Hypokinetic disorders are relatively uncommon in children. Although ataxia, weakness, and spasticity are characterized by motor dysfunction, by common convention these entities are not included among “movement disorders.” This review of movement disorders consists of two parts. Part I focuses on the most common movement disorders of childhood: tics and stereotypies. Part II examines chorea, dystonia, myoclonus, tremor, and drug-induced movement disorders. Most movement disorders in childhood arise from dysfunction in basal ganglia (caudate, putamen, globus pallidus, subthalamic nucleus, substantia nigra) and frontal cortex. However, the accomplishment of normal movement requires a multifaceted network of brain regions, including basal ganglia, frontal …