Chapter 3 - Classification of Movement Disorders

Abstract

Movement disorders are neurological syndromes that involve impaired performance 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, that manifests primarily in adulthood as Parkinson disease or one of the many forms of secondary parkinsonism. Hypokinetic disorders are relatively uncommon in children. Although weakness and spasticity are characterized by motor dysfunction, by common convention these entities are not included among “movement disorders.”