Essential tremor: treatment with beta-adrenoceptor blocking drugs
Essential tremor is a chronic disorder of movement. It shows a familial tendency and is more common in patients over the age of 50 years. The characteristics of the disease are well documented (for reviews see Critchley, 1972; Murray, 1981). Although patients suffering from clearly separate tremor-producing conditions such as Parkinson’s disease may occasionally be present in a group of essential tremor patients, when accurately diagnosed essential tremor is a monosymptomatic illness. That is not to say, however, that essential tremor patients are a homogeneous group. The variability in responsiveness to drug therapy that will be described suggests that a review of the current single classification may be in order. The tremor is an action or postural tremor, being absent when a limb is at rest. It can be seen in a limb held in a fixed position against gravity, the usual arrangement used during accelerometer recordings of tremor (Wilson et al., 1982). Patients may show additional intention tremors which increase in amplitude towards the end of intention movements. The tremor occurs in short bursts which correlate with electromyographic activity. The frequency of the tremor covers a range from some 6 to 12 Hz but an individual patient shows a generally stable frequency or pattern of frequencies when measured repeatedly over a period of time. Emotional and physical stress aggravate the tremor and this aspect of the disease presumably accounts for the limited effectiveness of anxiolytic agents such as chlordiazepoxide in the treatment of tremor (Critchley, 1972).
KeywordsEssential Tremor Muscle Spindle Lipid Solubility Postural Tremor Physiological Tremor
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