[How to clinically approach involuntary movements]

Abstract

Upon clinical examination of involuntary movement, its correct diagnosis and classification is most important for choosing its most appropriate treatment. Correct diagnosis of involuntary movements should be based on their clinical characteristics rather than laboratory data. First attention should be paid to the way of its occurrence; whether it repeats itself at a relatively regular period or it occurs irregularly. Among irregular movements, chorea and ballism (us) belong to the same category clinically as well as neuropharmacologically; both respond to benzodiazepine and D2 receptor blockers. Dyskinesia and akathisia are often drug-induced. Athetosis often overlaps chorea and dystonia. Dystonia is characterized by excessive muscle contraction in terms of strength, spread and duration. Recently involvement of the sensori-motor cortex is emphasized in generation of focal dystonia. Myoclonus is usually caused by abrupt muscle contraction but also by sudden cessation of muscle contraction (negative myoclonus). Myoclonus and tics are usually irregular, but they can be rhythmic or quasiperiodic. Tremor is often associated with dysfunction of basal ganglia, cerebellum or thalamus, but recently an increasing attention has been paid to involvement of the sensori-motor cortex. Some involuntary movement could show features of two or more kinds of involuntary movements or it may shift among different kinds of involuntary movements or among different subgroups of that particular involuntary movement. Therefore, it is not advisable to feel obliged to classify every single involuntary movement into any pre-existing category. Instead a more flexible approach is warranted.