Essential tremor
Essential tremor is an isolated, usually bilateral upper-limb action tremor lasting at least 3 years, diagnosed clinically after characterising the tremor and excluding parkinsonism, dystonia, ataxia, drugs and systemic causes.
Definition
Essential tremor is an isolated tremor syndrome of bilateral upper-limb action tremor lasting at least 3 years, with or without tremor in the head, voice or lower limbs and without another neurological syndrome such as dystonia, ataxia or parkinsonism. Essential tremor plus describes a similar tremor with additional mild neurological signs of uncertain significance.
First principles
Define the tremor before naming the disease
Describe the tremor by activation condition, distribution, symmetry, frequency, time course and associated signs. Current movement-disorder classification defines essential tremor as bilateral upper-limb action tremor for at least 3 years, with or without head, voice or lower-limb tremor, and without another neurological syndrome. A shorter-duration or evolving tremor is better described as indeterminate until its course is clear.
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