What is Tremor
Tremor is defined as an involuntary rhythmical movement and is often categorized in three positions which are: hands in repose (rest), hand held up with arms outstretched (postural), and during movement (intention). The amplitude, frequency and severity of the tremor vary from patient to patient, but at its worst, tremor can cause severe functional disability.
Causes of Tremor
There are various causes for tremor. The most common cause being Essential tremor (ET), Parkinson’s disease tremor (PD), Multiple Sclerosis tremor, Post Stroke tremor, Post Head Injury tremor etc. The diagnosis of various kinds of tremors is based on the clinical spectrum and radiological imaging.
Essential tremor (ET) is one of the most common tremor disorders. The characteristics of ET are its frequency being 4 – 12 Hz. and it is most pronounced during purposeful movement. This is in contrast to Parkinson’s disease tremor which is more dominant during rest. Essential tremor is often hereditary and is transmitted in an autosomal dominant mode. The disease progression of this tremor is fairly benign and it is likely to remain static over a long period of time. Another distinguishing feature of ET tremor is that it mainly involves the upper limb and spares the lower limb unlike PD tremor. At its worst the Essential tremor can be a severe functional handicap preventing the patient from the use of upper extremities.
Tremors of multiple sclerosis are much coarser and have larger amplitudes. The post stroke tremors and tremors due to other cerebral insults are less frequent and hence require specialist evaluation.
Treatment of tremors
Treatment for tremor entirely depend on two factors: one is its cause and the second is the amount of disability that it creates. For e.g. a mild tremor in an CEO of a company or a surgeon can be significantly disabling, whereas same may not be a problem to manual labourer. Parkinson’s disease tremors and essential tremors respond well to medical management. It is only a small fraction of patients who may require surgical interventions.
The most common surgery for controlling tremors is thalamic stimulation or thalamoty