Essential tremor

• What is essential tremor?
• Statistics on essential tremor
• Risk factors for essential tremor
• Progression of essential tremor
• Symptoms of essential tremor
• Clinical examination of essential tremor
• How is essential tremor diagnosed?
• Prognosis of essential tremor
• How is essential tremor treated?
• Essential tremor references

What is essential tremor?

Essential tremor (ET) is a disease of the central nervous system, although the exact mechanism is unknown. It is suspected that this disease occurs due to changes in the deep brain tissue, but this has yet to be proven.
ET usually affects only certain parts of the body, including:

• Hands;
• Arms;
• Face;
• Voice;
• Jaw;
• Less commonly: legs, walking ability, balance.

Statistics on essential tremor

ET is a common condition. It is the most common neurological cause of postural or action tremor, with the estimated prevalence of up to 10% of the population in the US.

Risk factors for essential tremor

The incidence of ET increases with age, hence age is a risk factor. It is more common as the age increases, having an average age of onset of 35-45 years old. If a person were to have ET, the disease would be prominent by 65 years of age, and virtually almost always present by 70 years old.
ET affects both sexes equally. However, the site of involvement of the tremor is different depending on different gender. Head tremor may be more frequent in women while postural hand tremor is more frequent in men.
Sometimes ET can be a familial disorder, in which a strong family history is seen. It is then called familial essential tremor.

Progression of essential tremor

The exact mechanism of ET is unknown. It is thought that certain pathways in the brain are affected where the control of fine movement occurs. However, no pathology has been identified with ET.

How is essential tremor diagnosed?

The diagnosis of ET is based on clinical history and examination. However, if the diagnosis is uncertain a full physical examination will be done. These include looking at the blood function, kidney function, liver function, thyroid function, and the body’s iron, vitamins and electrolytes level.

Prognosis of essential tremor

ET is not a life-threatening condition. Although there is no associated death rate, it can cause significant inconvenience to the patients. This is due to the social and functional embarrassment that usually occur in activities of daily living. As much as 85% of the patients with ET reported that this disease affected their lifestyle in certain ways.
Quality of life can be significantly impaired with ET. This include employment, normal outing activities such as dining out, attending parties, shopping alone, etc.

How is essential tremor treated?

There are relatively few medications that are effective in treatment of ET. Generally pharmacological agents are used as first line treatment of ET. These include:

• Beta-blockers: This is the most common medication used for treatment of ET. The prototype drug is propanolol. Multiple studies have shown that propanolol improves the symptoms ranging from 50-70% of the patients. However, no long term study has been conducted regarding the effect of propanolol in ET. Other beta-blockers include atenolol, metoprolol, sotalol and nadolol.
• Anticonvulsants: Primidone is an anticonvulsant that can be used in ET. The exact mechanism is unknown. If not tolerated due to the side effects, other anticonvulsants such as topiramate, gabapentin and levetiracetam can be used. However most of these anticonvulsants are not well studied – only small and short trials have been done to evaluate their effectiveness.

Other treatments include:

• Alcohol: This has been known to relieve symptoms of ET, and is one of the questions needed to be asked in clinical history. While using small amounts of alcohol before meals or social events is reasonable and commonly practiced, regular use is not recommended due to the development of tolerance. This will eventually lead to increasing amount of alcohol to achieve the same effect. Withdrawal effects may be significant once the alcohol is not consumed.
• Surgery: This can be a consideration for those who do not respond to the above treatment regimes. The surgical procedures are stereotactic thalamotomy or thalamic deep brain stimulation. Excellent results have been reported from these surgeries.

Essential tremor references

1. Calzetti, S, Findley, LJ, Perucca, E, Richens, A. The response of essential tremor to propranolol: evaluation of clinical variables governing its efficacy on prolonged administration. J Neurol Neurosurg Psychiatry 1983; 46:393
2. eMedicine: Essential tremor [online]. 2001. [Cited 2005 October 26th]. Available from: URL: http://www.emedicine.com/NEURO/topic129.htm
3. Hariz, GM, Lindberg, M, Bergenheim, AT. Impact of thalamic deep brain stimulation on disability and health-related quality of life in patients with essential tremor. J Neurol Neurosurg Psychiatry 2002; 72:47
4. Jefferson, D, Jenner, P, Marsden, CD. Beta-adrenoreceptor antagonists in essential tremor. J Neurol Neurosurg Psychiatry 1979; 42:904
5. Louis, ED, Marder, K, Cote, L, et al. Prevalence of a history of shaking in persons 65 years of age and older: diagnostic and functional correlates. Mov Disord 1996; 11:63
6. Up to Date: Tremor [online]. 2005. [Cited 2005 October 26th]. Available from: URL: http://www.utdol.com/application/topic.asp?file=move_dis/4697&type=A&selectedTitle=2~3