Disorders of the basal ganglia

Abstract

The classic clinical syndromes that result from abnormalities of the basal ganglia are disorders of movement. These may take the form of excessive involuntary movements (i.e., hyperkinesia) or decreased movement (e.g., hypokinesia). Hypokinesias such as bradykinesia (e.g., slow movement) or akinesia (e.g., absence or difficult initiation of movement) are often seen in Parkinson's disease and a few conditions that mimic this disorder. There are several forms of hyperkinesias and many different disease states that cause these symptoms. Among the most common forms of hyperkinesia are chorea, dystonia, tremor, and tics. The complex anatomic connections and physiologic associations of the basal ganglia often make it difficult to determine the anatomic locus of disease responsible for these abnormal patterns of movement. Similarly, with the exception of Parkinson's disease, the neurotransmitter aberrations responsible for many movement disorders are unknown and are often defined only by the mode of action of the drugs used to treat them.