Essential tremor
| Essential tremor | |
|---|---|
| Classification and external resources | |
| Specialty | Neurology |
| ICD-10 | G25.0 |
| ICD-9-CM | 333.1 |
| OMIM | 190300 602134 |
| MedlinePlus | 000762 |
| eMedicine | neuro/129 |
| MeSH | D020329 |
Essential tremor (ET, also referred to as benign tremor, familial tremor, or idiopathic tremor) is the most common movement disorder; its cause is unknown. It typically involves a tremor of the arms, hands or fingers but sometimes involving the head, vocal cords or other body parts during voluntary movements such as eating and writing. It is distinct from Parkinson's disease—and often misdiagnosed as such—although some individuals have both conditions. Essential tremor is commonly described as an action tremor (i.e., it intensifies when one tries to use the affected muscles) or postural tremor (i.e., present with sustained muscle tone) rather than a resting tremor, such as is seen in Parkinson’s, which is usually not included among its symptoms.
This type of tremor is often referred to as "kinetic tremor".
Essential tremor has been known as "benign essential tremor", but the adjective "benign" has been removed in recognition of the sometimes disabling nature of the disorder.
In mild cases, ET can manifest as the inability to stop the tongue or hands from shaking, the ability to sing only in vibrato, and difficulty doing small precise tasks such as threading a needle. Even simple tasks like cutting in a straight line or using a ruler can range from difficult to impossible, depending on the severity of the condition. In disabling cases, ET can interfere with a person's activities of daily living, including feeding, dressing, and taking care of personal hygiene. Essential tremor generally presents as a rhythmic tremor (4–12 Hz) that occurs only when the affected muscle is exerting effort. Any sort of physical or mental stress will tend to make the tremor worse.
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, intention tremor of the arms and rest tremor in the arms. Some patients may have unsteadiness and problems with gait and balance.
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. Tremor and disease activity/intensity can worsen in response to fatigue, strong emotions, low blood sugar, cold and heat, caffeine, lithium salts, some antidepressants, and other factors. It is typical for the tremor to worsen in "performance" situations, such as when writing a check for payment at a store or giving a presentation.
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