What is Essential Tremor
Essential Tremor (ET) is a relatively common movement disorder that affects about 10 million Americans and millions more worldwide.
What is essential tremor?
Tremor is an involuntary – usually rhythmic – movement that results in shaking of a body part. "Tremore seplice essenziale," or essential tremor (ET), was the term coined by an Italian physician, Pietro Burresi in 1874. ‘Essential’ does not mean that it is needed or important, rather that it is idiopathic, or has no known cause. This condition has been referred to as “benign familial tremor,” which is a misnomer, since ET is not always ‘benign’ and runs in families about half the time.
Is essential tremor the same as Parkinson’s disease?
ET is not Parkinson’s disease (PD), although both can involve tremor. Typically, with PD, tremor is more noticeable while the extremity is at rest and can actually improve or disappear when the affected limb is in motion. It is not common to have both ET and PD, but it is possible. That is why if you are experiencing tremor, it’s important to see a neurologist who specializes in movement disorders.
What are the symptoms of essential tremor?
The cardinal symptom of ET is tremor. The commonly affected body parts include:
- vocal cords (voice tremor)
The tremor can occur when an extremity is being held in posture, or in action, while performing a voluntary movement. For example, the hand can tremor when holding a TV remote (postural tremor), or when bringing a cup to one’s mouth (action tremor).
Interestingly, many patients will report that their tremor improves when they drink alcohol. But there are better and safer ways to treat the condition.
Is essential tremor common?
If you are experiencing ET, it may help to know you are not alone. Essential tremor affects about 4-5% of people between the ages of 40 and 60, and an estimated 6.3-9% of people who are 60 or older. For example, in Rhode Island there are about 240,000 people who are older than 60; there would be about 15,000-21,600 people over the age of 60 in Rhode Island with this condition.
ET can start at any age, but it is more common in middle or later years of life. Many times, the tremor begins in young adulthood but is not very noticeable or disturbing until middle-age.
What is the prognosis for essential tremor?
Typically, ET worsens over time, but very slowly -- usually years and sometimes decades. ET is not life-threatening. However, it can be socially embarrassing and even disabling, affecting one’s ability to perform daily activities.
What causes essential tremor?
We do not yet know the cause of ET. However, we do know that up to half of patients who have ET also have a family history of the condition. Researchers have identified genes that may be involved, but genetic testing is not yet available for routine workup of ET.
Imaging studies of the brain suggest that the part of the brain known as the cerebellum and its connections are disrupted in people with ET. The cerebellum is located at the back of the brain and is responsible for complex motor functions and allows for balance when walking or standing.
Other possible causes for tremor include:
- certain medications such as anti-depressants
- drugs such as amphetamines and caffeine
- metabolic conditions such as hyperactive thyroid
- physiological states such as anxiety/stress
How is essential tremor diagnosed?
The diagnosis is made by a thorough review of a patient’s medical history and a clinical examination. There is no blood test or brain scan that can diagnose ET, but these tests are sometimes performed to rule out other causes of tremor. As a result, it is important to see a neurologist, preferably one who specializes in movement disorders and therefore, can provide the correct diagnosis.
How is essential tremor treated?
Unfortunately, there is no cure for ET, but there are a few treatments that might improve the tremor. In some cases, the tremor is mild enough that it doesn’t warrant treatment.
Medications for essential tremor
Most of the medications work to calm the nerves, although they may have other functions as well. For example, drugs for blood pressure control or anti-seizure medications are often the first-line treatment. If they are not effective enough, the treating physician may use other drugs or drug classes to achieve better tremor control. Some medications may be used in combination.
Surgical treatment for essential tremor
When the tremor does not respond well to medications, or severe symptoms impair an individual’s quality of life, then surgical treatment can be considered. The two main surgical treatments are deep brain stimulation (DBS) and focused ultrasound (FUS).
DBS involves implanting a thin wire into the brain, which is attached to a pulse generator battery in the chest wall. The stimulator can then send an electrical signal to the area of the brain that controls the tremor, similar to a pacemaker for heart conditions. The stimulation acts as a way to block the messages from your brain that cause the tremor. It has been shown to be very effective in providing relief for some patients and improving their ability to perform daily activities. DBS is a commonly used surgical approach for ET because it is effective, can treat tremors on both sides of the body, has relatively low risk and its effects are reversible.
FUS involves placing a small, precisely targeted lesion (disconnection) in the brain region associated with tremor. Unlike DBS, FUS does not require implanted hardware or even a skin incision, because the ultrasound energy can be delivered through the skin and skull into the brain with MRI guidance (it does, however, require a full head-shave). FUS is a single-day, outpatient procedure and can result in immediate and long-lasting improvements in tremor. FUS can significantly reduce tremors on one side of the body, but is not typically used to treat tremors on both sides.
Any surgical procedures carry risk and should be thoroughly discussed with an experienced specialist prior to surgery.
Treatment for essential tremor near you
The Fast Track Deep Brain Stimulation Clinic and the Focused Ultrasound Program at Rhode Island Hospital in Providence, Rhode Island offer an experienced multidisciplinary team consisting of a movement disorders neurologist, a functional neurosurgeon, a neuropsychologist, psychiatrist, and physical, occupational and speech therapists. Our team of experts provides evaluations for potential DBS and FUS candidates and works together to determine the most appropriate recommendations for each patient.
About the Author:
Umer Akbar, MD, and Wael F. Asaad, MD, PhD
Dr. Umer Akbar is a neurologist with expertise in the medical and surgical management of movement disorders. He is co-director of the Movement Disorders and Deep Brain Stimulation programs at Rhode Island Hospital.
Dr. Wael Asaad is a neurosurgeon with expertise in functional neurosurgery for movement disorders and psychiatric disease and traumatic brain injury. He is also director of the Functional Neurosurgery & Epilepsy program; co-director, Deep Brain Stimulation; and laboratory director of cognitive neurophysiology & neuromodulation.
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