Essential Tremor (ET)
Essential Tremor (ET): The diagnosis of ET is based on the presence of bilateral and usually symmetrical postural or action tremor which is visible and persistent, and which involves hands and forearms, (Deuschl, 1998). Essential Tremor can also affect head and voice. Chin or leg involvement is atypical. Some patients, especially female, present with head tremor as an isolated manifestation of ET.
Caution is taken to rule out an underlying cervical dystonia with a prominent tremor component. The possibility of underlying symptomatic cause (drugs, toxins, metabolic abnormalities) should also be excluded prior to making a diagnosis of ET.
ET is a monosymptomatic disease, meaning that no other abnormal neurological findings are present. ET has strong familial predisposition, with about 50% of patients having a positive family history for tremor. This indicates a likely autosomal dominant inheritance, though the gene has yet to be identified. Lack of family history does not preclude the diagnosis of ET.
Symptoms have an insidious onset with a variable rate of progression. The most disabling feature of ET is action/kinetic tremor of the arms, which interferes with the patient's ability to perform daily activities, like eating, drinking, or writing. Since patients with severe ET can be quite disabled, the label benigntremor is a misnomer. A number of patients have a combination of ET and other movement disorders (dystonia, parkinsonism, myoclonus, or restless legs syndrome).
Relevant Links: Essential Tremor and Other Tremor Disorders