Criteria for definite ET (all five must be true)
1. On examination, a + 2 postural tremor of at least one arm (a head tremor may also be present, but is not sufficient for the diagnosis).
2. On examination, there must be a. a + 2 kinetic tremor during at least four tasks, or b. a - 2 kinetic tremor on one task and a + 3 kinetic tremor on a second task; tasks include pouring water, using a spoon to drink water, drinking water, touching finger to nose, and drawing a spiral.
3. If on examination the tremor is present in the dominant hand, them by report it must interfere with at least one activity of daily living (eating, drinking, writing, or using the hands). If on examination the tremor is not present in the dominant hand, then this criterion is irrelevant.
5. Not psychogenic (bizarre features, inconsistent in character, changing, subject is distractable, or other psychiatric features on examination).
Criteria for probable ET (either 1a or 1b must be true; 2 and 3 must be true)
b. Head tremor is present on examination.
2. Use of medications, alcohol, Parkinsonism, dystonia, other basal ganglionic disorders, and hyperthyroidism are nor potential etiological factors.
1. On examination, a + 2 kinetic tremor must be present on three tasks 0 to +3 Tremor ratings. 0. No visible tremor. +1. Low amplitude, barely perceivable tremor, or intermittent tremor. +2. Tremor is of moderate emplitude (1-2 cm) and usually present it is clearly oscillatory. +3. Large amplitude (>2 cm), violent, jerky tremor resulting in difficulty completing the task owing to spilling or inability to hold a pen to paper.
ET, essential tremor.
(Reprinted with permission from Louis ED, Ford B, Lee H, Andrews H, Cameron B. Diagnostic criteria for essential tremor: a population persepective. Arch Neurol 1998;55:823-828 and from the American Medical Association.)
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