Tremor
Tremor is the most common movement disorder characterized by rhythmic, involuntary, oscillatory movements of a body part. It can exist as an independent clinical disorder (for example: essential tremor and physiological tremor) or it can be part of a wide spectrum of symptoms of a disease (for example: Parkinson's disease and Wilson's disease). As with all movement disorders, history and clinical examination are the most important for establishing an accurate diagnosis.
Tremor is primarily divided into action tremor and resting tremor (table 1-3). It can also be divided according to the affected parts of the body and according to the amplitude and frequency.
Tremor at rest occurs in a part of the body that is not willingly active, completely directed against the force of gravity (for example: a hand resting on a table).
Action tremor is any tremor that occurs during voluntary muscle contraction. It includes postural, kinetic and isometric tremor. Postural tremor occurs when maintaining the position of a part of the body against the force of gravity (for example: holding arms outstretched). Kinetic tremor occurs during voluntary movement and can be simple (voluntary movements that are not goal-directed, for example: writing, taking a cup and drinking) and intentional (occurs with an increase in amplitude at the end of a visually guided movement to a specific goal, typical for a cerebellar disease).
Essential tremor (ET) is the most common type of tremor syndrome and thus also the most common form of movement disorder. The prevalence is from 1% to 22% in the adult population. It can appear in any age group with almost 2% of the population over 60 being affected. A positive family history in about 17% to 100% of patients indicates the importance of genetic inheritance. Essential tremor is inherited in an autosomal dominant manner with variable penetrance. Clinically, it is presented as a bilateral, symmetrical, postural or kinetic tremor that most often affects the hands and forearms. In addition to these main diagnostic criteria it typically lasts longer than three years with a positive family history and a favorable response to alcohol consumption. This tremor is usually harmless and the main difficulty is related to the cosmetic and social discomfort of the person with the tremor.
Other specific tremor syndromes include:
Physiological tremor: a tremor around each joint that can oscillate freely present in every healthy individual; it can be increased by the influence of various factors (stress, fatigue, physical activity, emotions, hypoglycemia, hyperthyroidism and influence of medical drugs).
Orthostatic tremor: high-frequency tremor of the legs which causes instability or fear of falling; some consider the ET variant to be a part of dystonic tremor or a separate variant; the effectiveness of clonazepam has been demonstrated therapeutically.
Tremor during specific tasks: a typical representative is tremor while writing and it is important to distinguish it from dystonia while writing, they can occur together and in treatment the use of propranolol, primidone, anticholinergics and DBS in severe cases is attempted.
Drug-induced tremor: it can be presented as increased physiological tremor or tremor at rest due to taking neuroleptics; in addition to neuroleptics there are also drugs for asthma (beta adrenergic agonists), antiarrhythmics (amiodarone), lithium, amphetamine and valproate.
