Essential tremor (ET) is a progressive neurological disease whose most recognizable feature is a tremor of the arms that is apparent during voluntary movements such as eating and writing. This type of tremor is often referred to as "kinetic tremor". The tremor may also occur in the head (neck), jaw and voice as well as other body regions, with the general pattern being that the tremor begins in the arms and then spreads to these other regions in selected patients. Women are more likely to develop the head tremor than are men. Other types of tremor may also occur, including postural tremor of the outstretched arms, intentional tremor of the arms and rest tremor in the arms. Some patients may have unsteadiness and problems with gait and balance that are above and beyond that due to normal aging. In addition to these motor problems, a variety of non-motor features have recently been linked with ET. These include anxiety and depressive symptoms as well as cognitive difficulty. Recent studies have demonstrated that ET may be associated with an increased risk of developing dementia . ET is one of the most common neurological diseases, with a prevalence of approximately 4% in persons aged 40 and older and considerably higher among persons in their 60s, 70s, 80s, and 90s. Aside from enhanced physiological tremor, it is the most common type of tremor and also one of the most commonly observed movement disorders. Essential tremor was also previously known as "benign essential tremor", but the adjective "benign" has been removed in recognition of the sometimes disabling nature of the disorder. Although often mild, patients with severe tremor have difficulty performing many of their routine activities of daily living.
ET does sometimes occur in combination with other neurological disorders such as dystonia. In addition, there is a link between ET and Parkinson's disease, with ET patients approximately 4 - 5 times more likely to develop Parkinson's disease.
Tremor intensity can worsen in response to fatigue, strong emotions, low blood sugar, cold, caffeine, lithium salts, some antidepressants or other factors. It is typical for the tremor to worsen in "performance" situations, such as when making out a check at a checkout stand.
ET-related tremors do not occur during sleep, but patients sometimes complain of an especially coarse tremor upon awakening that becomes noticeably less coarse within the first few minutes of wakefulness.
In mild cases, ET can manifest as the inability to stop the tongue or hands from shaking, the ability to only sing in vibrato, and difficulty to do small precise tasks such as threading a needle. In disabling cases, ET can interfere with a person's ability to perform tasks of daily living, including feeding, dressing, and activities of personal hygiene.
ET is generally progressive in most cases (sometimes rapidly, sometimes very slowly), and can be disabling in severe cases.
The two medications that are prescribed most commonly for control of ET symptoms are the anticonvulsant Primidone (Mysoline) and the beta-blocker propranolol (Inderal). Self medication with small amounts of alcohol has been shown to give short term relief from tremor.
Minor cases of ET can be treated with physical therapy and development of the muscles in the sections of the body that are severe in their shaking.
The National Tremor Foundation(NTF), founded in 1992, is a British friendly organisation based in Essex, England, an affiliate of the International Tremor Foundation, which was founded in 1988. The organisation's primary work is production of a quarterly informational newsletter. The NTF also maintains a list of ITF medical advisors, and facilitates the formation of self-help groups. NTF was granted charitable status in 1994.
IBM created a peripheral device that filters out tremoring movements of the hand. The hardware adapter, termed AMA, is connected between the computer and the input device. It is switched on or off and adjusted on the device for tremor severity.
Other tools have also been adapted for people with tremors; for example, eating utensils which are weighted to help damp out tremor.