What Is Essential Tremor?

Date: Aug-20-2012Essential tremor refers to the uncontrollable shaking or trembling of a person's body, usually the hands and head, but can also affect the jaw, feet, tongue and face, when they are resisting the force of gravity. Some sufferers may have a distinctive shaky voice when talking. Essential tremor is the most common movement disorder and is estimated to affect nearly 10 million people in North America and Western Europe. Experts say that in over half of all essential tremor cases, the condition is inherited.

In most cases of essential tremor, which is often referred to as kinetic tremor, symptoms start in the hands and arms and then gradually spread to other parts of the body. It used to be called "benign essential tremor ", but the adjective "benign" has been dropped because it can eventually become severely disabling.

For most sufferers, essential tremor is nothing more than a slight nuisance. However, symptoms tend to be progressive - they get worse with time. In severe cases this movement disorder can be disabling, and seriously undermines the patient's ability to go about their daily activities, such as drinking a glass of water, tying things up, or writing.

We all experience minor tremor now and again when we hold, for example a cup of tea or coffee out in front of us; this is normal. Tremor is usually more noticeable as people reach old age. Essential tremor is more persistent and noticeable and tends to gradually get worse.

According to health authorities in Western Europe, USA, Canada, Australia and Japan, essential tremor affects approximately 4% of all adults. It affects males and females equally - the head tremor tends to affect women more. Although essential tremor can start at any age, onset usually occurs in older people.

According to Medilexicon's medical dictionary, Essential Tremor is:

"An action tremor of 4-8 Hz frequency that usually begins in early adult life and is limited to the upper limbs and head; called familial when it appears in several family members."
What are the signs and symptoms of essential tremor?
A symptom is something only the patient feels and has to describe to the doctor, such as pain, dizziness, nightmares or discomfort, while a sign is something others can detect, such as a rash, swelling or fever.

There is only one main symptom of essential tremor - trembling. In the majority of cases, the hands tremble in an up-and-down movement.

Tremor may affect the following parts of the human body:

Eyelids
Face
Feet (rare)
Hands (and arms)
Head
Jaw
Larynx (voicebox)
Legs rare)
Tongue

Signs and symptoms tend to start later on in life. The earlier in life they begin, the worse the condition tends to be and become.

When the body part that is usually affected is at rest, there are no symptoms. The condition seems to be more noticeable when it is applying a force against gravity.

For most patients, both sides of the body are affected equally. The problems tend to become particularly noticeable when the patient tries to write, hold out a drink (especially with an outstretched arm), do some sewing or knitting, or any other task that requires dexterity.

Signs and symptoms tend to worsen when the patient:

Has consumed large amounts of caffeine
Is anxious
Is doing something strenuous
Is on certain medications
Is stressed
Is upset

Although symptoms tend to be mild in most cases, the condition becomes progressively worse over time.
What are the causes of essential tremor?
Research has shown that the ETM1 gene, also known as FET1, which exists in chromosome 3, as well as ETM2 which is located in chromosome 2, are linked to a higher risk of developing essential tremor. As two genetic variations on different chromosomes have so far been identified, the condition is probably associated with various genes.

Scientists at the Universite Laval, Canada, noticed a drop in GABA receptor concentrations in the cerebellum of patients with essential tremor. GABA receptors pass chemical messages which transmit inhibitory data to various parts of the brain. The researchers believe that a decrease in GABA receptors in the cerebellum may contribute to essential tremor symptoms.

Experts believe the gene mutation has an impact on the cerebellum and the inferior olive (brain areas), altering the way signals are sent from the brain, down the nerves to the muscles.

Approximately half of all essential tremor cases are thought to be inherited. Nobody knows why patients with this condition who have no family history or genetic mutation become affected.

There is no test available today to determine whether a patient's essential tremor is caused by a specific gene.

Triggers - some people find that specific actions may bring on their symptoms. Examples include:

Applying make-up
Drinking a glass of water
Eating
Shaving
Writing
Some people find that their symptoms are worse if they are tired or did not get enough sleep
Long-term daily consumption of at least three units of alcohol per day raises essential tremor risk, a 2009 study found.

Several illnesses and conditions are associated with "normal" tremor, such as hyperthyroidism (overactive thyroid), Parkinson's disease, peripheral neuropathy, stroke, dystonia, MS (multiple sclerosis), alcohol withdrawal, illegal drug abuse, and some medications.
How is essential tremor diagnosed?
There is no "essential tremor test". Therefore, doctors will go through a process of elimination, ruling out possible illnesses and conditions, determining whether there is a family history, as well as carrying out a physical exam. The doctor will also check what medications the patient is on, in case the tremors are linked to them.

The following diagnostic tests may be ordered:
A CT (computerized tomography) scan of the brain
An MRI (magnetic resonance imaging) scan of the brain
An EMG (electromyography) test, to determine the electrical activity of the muscles. This test can help the doctor see whether there is any nerve damage.
Blood tests
Urine tests

The patient may be asked to drink from a glass, hold his/her hands outstretched, write, or draw a spiral to evaluate the tremor itself. The doctor will also examine the patient's muscle strength and tone, tendon reflexes, gait, posture and coordination, and the ability to feel specific sensations.
What are the treatment options for essential tremor?
If the patient's symptoms are mild, the doctor may advise no treatment. However, if the individual's quality of life and ability to carry out everyday tasks are affected, treatment will be recommended.

The following medications have been found to help with essential tremor symptoms:
Beta blockers - designed to treat hypertension (high blood pressure), these drugs may help, especially those who take medications for asthma, diabetes or certain heart conditions. Examples include propranolol, atenolol, nadolol, and metoprolol.

Anticonvulsants (epilepsy medications) - may be prescribed if the patient did not experience symptom-relief from beta blockers. Examples include primidone, topiramate, and gabapentin.

Sedatives - these medications may be prescribed if the tremors are triggered by tension or anxiety and the above medications did not work. Examples include Valium (diazepam) and Xanax (alprazolam).

Botox (OnabotulinumtoxinA) injections - especially if the head and/or voice are affected. Treatment is usually effective for about three months. Experts say that Botox should not be used to treat hand tremors because the muscles in the area may become weaker.

Sometimes essential tremor symptoms may be so severe that surgery is recommended (rarely). The following surgical procedures are possible:
Deep brain stimulation - electrodes are placed in the thalamus, in the brain. Fine needles go through tiny holes in the skull. The whole procedure is done with a general anesthetic. Thin wires connect the electrodes to a pulse generator device which is implanted under the skin in the chest. The generator helps regulate brainwaves and control tremor by sending electric currents.

Health authorities in the United Kingdom say that deep brain stimulation is effective in treating severe essential tremor, but nobody knows how successful it is long-term. Several studies have found that tremor symptoms are reduced by about 90% with this treatment.

Side effects are very rare, but may include fluid in the brain, infection of the surgical scar, tingling, and bleeding in the brain. Stroke is also a possible (very rare) risk.

77% of essential tremor patients who underwent deep brain stimulation no longer needed to take any medications 12 months after the procedure, researchers from the University of South Florida reported at the annual meeting of the American Academy of Neurology in Honolulu, Hawaii.

Thalamotomy - a small hole is made in an area of the brain called the thalamus.

The thalamus (red) is the target part of the brain in deep brain stimulation and thalamotomy

Deep brain stimulation is said to have fewer side effects than Thalamotomy.

Physical therapy (UK: physiotherapy) has helped some patients control their tremors, as well as improving their muscle control and coordination.

Occupational therapy - this involves seeing an Occupational Therapist, who may recommend some adaptations to make daily activities easier, such as:
Having heavier cups, glasses, plates and utensils
Using thick pens and pencils for writing
Using wrist weights

Essential Tremor Guidelines - American Academy of Neurology
On October 19th, 2011, the American Academy of Neurology issued new guidelines on the best ways to treat essential tremor. According to the guidelines, the hypertension drug propranolol and the anticonvulsant primidone are the best medications for improving trembling symptoms in people with essential tremor.

Theresa A. Zesiewicz, MD, a Fellow of the American Academy of Neurology, and co-author of the guidelines, said:

"More and better research is needed since not all people with essential tremor benefit from these drugs. For people who are not benefitting from these drugs, it's important they work with their neurologist to explore other types of treatments."

The guidelines also mentioned deep brain stimulation, Thalamotomy, and some other drugs may be helpful for those who did not benefit from the two recommended drugs.

The 2011 guidelines differed from the one issued in 2005, which did not recommend using some anti-seizure medications.

Written by Christian Nordqvist

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