Diagnosis and treatment of involuntary movements : a focus on tremors

Abstract

Involuntary movements, a collective term for movements occurring without volition, are the hallmark of hyperkinetic movement disorders. The main types of hyperkinetic movement disorders comprise restless leg syndrome, tremor, chorea, dystonia, myoclonus, and tics, along with other symptoms including akathisia, hemifacial spasm, myokymia, stereotypies, periodic limb movement disorder, hyperekplexia, and alien hand syndrome. Variations in movement symptoms termed dyskinesia are often observed in clinical practice in response to levodopa and dopamine agonist treatment. Despite falling outside the narrow definition of involuntary movements, psychogenic involuntary movements that can be temporarily voluntarily suppressed and involuntary movements caused by adverse drug effects also require attention. Most involuntary movements can be diagnosed through observation of clinical characteristics. However, it is important to begin by accurately noting the observed movements without trying to fit them into an existing diagnostic category. The initial focus of observation should be temporal patterns of occurrence, specifically whether movements are irregular or have a constant or periodically recurrent rhythm. Tremors are characterized by constant rhythmic oscillations in contrast with the irregular pattern presented by other types of involuntary movement. In cases where it is difficult to differentiate between tremors and other movement disorders, skin palpation and surface electromyography are useful for diagnosis. The choice of drug therapy among the many available types should be based on the pathophysiology of the hyperkinetic (involuntary) movements or underlying disorder.