Abstract
Movement disorders arise from alterations in the basal ganglia pathway. They can exist alone or secondary to another disease, are common, and affect all age groups. This chapter provides an overview of examination findings, disease features, genetics, and demographic variation geared to help the practicing neurosurgeon recognize a given disorder. The focus is therefore on describing differentiating features on physical examination, grouped primarily by movement phenomenology: hyperkinesia, hypokinesia, discoordination, and mixed presentations. Hyperkinesias are defined by excess movement and include tremor, chorea, myoclonus, dyskinesia, tics, akathisia, and stereotypies. Hypokinesias are defined by reduced movement, and include gait freezing, stiff person syndrome, and neuromyotonia. Disorders of coordination (primarily ataxias) are also discussed. Mixed disorders include the parkinsonisms, dystonias, and disorders arising from systemic disease (toxic, metabolic, and autoimmune). More common syndromes are found in the printed text, while discussion of rarer disorders can be found in the online content.