[Most frequent causes for hand tremor in clinical practice]

The author summarises the various origins of hand tremor. Physiologic tremor can be demonstrated in any individual. This tremor is normally recordable at a stable frequency of 8-10 Hz, though this can be influenced by age, the amplitude can vary substantially. Physiological tremor is believed to have its origin in the mechanical properties of the extremities, and the firing properties of motoneurones. Essential tremor is an inherited autosomally dominant phenomenon, and is characterised by action and postural tremor. It is progressive with age. The use of low doses of theophylline in the treatment of essential tremor is emphasised, in view of the low incidence of side effects. A hypothesis is also presented to account for essential tremor in terms of an imbalance in the activity of excitatory and inhibitory amino acid system. Parkinsonian tremor may begin as postural or resting tremor on one side, and it is reduced by active movement of the affected extremity. The prognosis of Parkinson's disease presenting with tremor is better when presenting with hypokinesia. The increasing use of non-specific drugs in the treatment of Parkinsonism, and the use of thalamic high frequency stimulation are indicated.