2 Therefore, the examination should be comprehensive. As there are no validated serological, radiological, and pathological markers in ET, the diagnosis is primarily based on clinical findings (box 1). Evidence supporting various available strategies is then presented, followed by a review of established guidelines.ĮSSENTIAL TREMOR: THE MOST COMMON FORM OF ACTION TREMORĪction tremor refers to any tremor that is produced by voluntary contraction of muscles, including postural, isometric, and kinetic tremor.
#Tremulous movemnt how to
This article discusses different types of tremor with an emphasis on salient features and how to distinguish them clinically. Tremor can present alone or as part of a neurological syndrome, for example multiple sclerosis, dystonia, and neuropathy. Physiological tremor is an action tremor and is present in every healthy person under certain conditions. The most common cause of postural and kinetic tremor is essential tremor (ET). The most common cause of resting tremor is idiopathic Parkinson’s disease (PD). Resting tremor is suspected, if it occurs with the patient sitting with his arms firmly supported without any voluntary activities, if it increases with mental stress (counting backwards), and if it is suppressed by voluntary movements. 1– 3 Action tremor, the most prevalent of these types of tremor, occurs during sustained extension of the arm and during voluntary movements, such as writing or typing. Different classifications of tremor have been proposed although the most useful and widely accepted classification divides tremor according to the behaviour it occurs, that is rest and action tremor, which is further subdivided into postural and kinetic tremor (table 1).
Various types of tremor can be distinguished clinically, based on the activation condition, frequency, and topographical distribution. The first step in evaluating any patient with tremor is to characterise the tremor. EPC is associated with EEG changes (which may need to be identified with back-averaging techniques), and MRI changes in contralateral sensorimotor cortex. Lastly, epilepsia partialis continua (EPC) can produce regular jerks of the arm or hand, which can be difficult to distinguish from tremor. Stereotypies may have rhythmic components, but nevertheless are dominanted by complex movements. Asterixis can be distinguished from tremor on the basis of electromyographic (EMG) findings of prolonged absence of EMG activity during “flapping” or abduction of the upper extremities. Clonus, unlike tremor, represents a rhythmic movement, which is increased by muscle stretching. Tremor may be confused with rhythmic myoclonus (incorrectly termed cortical tremor), which is typically characterised by brief muscle twitches, confined to one limb or to adjacent body regions, associated with spike-wave complexes on the electroencephalogram (EEG) or spinal lesions. It is differentiated from other involuntary movement disorders, such as chorea, athetosis, ballism, tics, and myoclonus, by its repetitive, stereotyped movements of a regular amplitude and frequency. It is defined as an involuntary, approximately rhythmic, and roughly sinusoidal movement of one or more body parts. Tremor is one of the most common involuntary movement disorders seen in clinical practice. Evidence supporting various strategies used in the differentiation is then presented, followed by a review of formal guidelines or recommendations when they exist. This article focuses on a practical approach to these different forms of tremor and how to distinguish them clinically. Essential tremor and the tremor of Parkinson’s disease are the most common tremors encountered in clinical practice. The causes of tremor are heterogeneous and it can present alone (for example, essential tremor) or as a part of a neurological syndrome (for example, multiple sclerosis). In addition to the detailed history, the differential diagnosis is mainly clinical based on the distinction at rest, postural and intention, activation condition, frequency, and topographical distribution.
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