Essential Tremor – OpEd

Essential Tremor (ET), one of the most common movement disorders, is estimated to affect nearly 7 million individuals in the USA. Generally, ET patients present with “involuntary, rhythmic, oscillatory movements of a body part in motion (action tremor)”. Facts about Essential Tremor from the International Essential Tremor Foundation (IETF) are given here

Recently, in a paper published in JAMA NETWORK, W. JeffreyElias,MD, Department of Neurological Surgery and Binit B.Shah,MD,Department of Neurology, University of Virginia, Charlottesville, cautioned that prevalence of ET is likely underestimated because epidemiologic studies have found that many patients do not seek medical evaluation of tremor.

Essential Tremor studies

Researchers have reviewed ET studies in 1998 and 2010. A more recent review by Elan D. Louis, MD, MSandMorgan McCreary, PhD Department of Neurology, University of Texas Southwestern, Dallas, USA (Tremor and other Hyperkinetic Movements on line 9 July 2021) covered prevalence of ET in population-based epidemiological studies since then and derived a precise summary estimate of prevalence of ET and examined differences in prevalence across studies. This review with 78 relevant references may probably be the most authentic and extensive.

These researchers highlighted the importance of such estimates because they form the numerical basis for public health initiatives and offer clues about underlying biological factors of mechanistic importance.

A comprehensive meta-analysis which covered 42 population-based prevalence studies of just over 540 000 individuals in 23 countries reported a pooled prevalence of ET of 1.33% among all age groups and a prevalence of 5.79% in individuals 65 years or older.

The analysis provided more information:

• Among patients 90 years or younger, some small studies have reported an ET prevalence of greater than 20%. 
• Patients with young-onset ET, defined as onset at 40 years or younger, often have a family history of ET. 
• Among 104 individuals with young-onset ET evaluated at tertiary referral centers in the US, 86 (82.7%) had a family history of ET.
• In a population-based sample in Turkey, 10 of 17 patients (52.6%) with young-onset ET had a family history of ET.²

Other observations

ET is not associated with a shorter life expectancy. However, it may cause difficulty with daily living activities such as eating, drinking, and writing, which can result in functional disability causing social embarrassment. Patients with ET face an increased risk of being diagnosed with Parkinson disease.

Researchers noted that a study of 3813 individuals in Spain reported that 12 of 207 patients (5.8%) with ET developed Parkinson disease compared with 56 of 3606 controls (1.5%) after a median follow-up of 3.3 years.

How do the symptoms of ET typically begin? It begins in upper extremity and involves both upper extremities within several years. Some individuals may have a mild tremor that remains stable for decades before developing ET symptoms that interfere with daily activities.

Though physicians knew about the prevalence of ET for a long time, the pathophysiology of ET remains unclear, although structural and functional magnetic resonance imaging (MRI) studies have revealed gray and white matter structural damage to the cerebellum and alterations in connectivity between the cerebellum and various cortical brain areas.

Diagnosis of ET

Frequently, primary care clinicians look at history of the patients and carry out their physical examination to diagnose ET. Physical examinations typically reveal upper extremity tremors but may also involve tremors of the head, jaw, neck, or voice.

Action tremors occur with any voluntary movement of the body and include postural, kinetic, and intention tremors. Clinicians can assess postural tremor by having patients hold a position against gravity (such as outstretched arms). Finger-to-nose testing can identify kinetic tremors, which does not change throughout the phases of movement, and intention tremor, which increases as the target is reached.Individuals with ET seldom have a resting tremor, defined as a tremor in a fully supported unmoving body part, and, if present, it is suppressed by performing a mental task such as counting backward. In contrast, a resting tremor is common in Parkinson disease and is accentuated with mental tasks. Masked facies, hypophonic speech, bradykinesia, rigidity, and asymmetrical arm swing or stride length are also suggestive of Parkinson disease.

Other factors

When examining an individual with a tremor, clinicians should also look for symptoms of hyperthyroidism (eg, palpitations, unintentional weight loss). They also screen for use of medications or illicit drugs that may cause or worsen tremor.

Physicians can carry out brain imaging (head computed tomographic imaging or MRI) in patients with focal neurologic deficits to assess a structural cause, if any, of tremors.

Treatment of ET

Occupational therapy and adaptive devices (eg, weighted or oscillating utensils, metal cups, wrist weights), which can help manage mild symptoms are typical nonpharmacological treatments for ET. Lifestyle modifications, including caffeine cessation and avoidance of alcohol overuse, can also decrease tremor.

The researchers described the first line of pharmacologic treatment and the results of treatment with certain drugs. Propranolol is the only US Food and Drug Administration–approved treatment for ET. The paper listed other forms of treatment such as stereotactic surgical procedures and electrical stimulation therapy

Conclusions

“ET is a common movement disorder that may cause substantial functional disability. Patients may benefit from occupational therapy and adaptive devices to help manage symptoms. First-line pharmacologic treatment includes propranolol and primidone. Patients with tremors whose diagnosis is uncertain or who do not improve with medications should be referred to a movement disorder specialist. Potential treatment options include additional medications or referral to neurosurgery for a stereotactic procedure that targets the thalamus.” The researchers concluded.

Self declared conflict of interest

This writer was inspired to write this article when he came to know that an all-girls (Priya, Anoushka Aanya and Sahana) team of middle school students-Goofy Gyros) represented Massachusetts at the 2024 FIRST Championship World Festival in Houston, Texas in April 2024.Sahana is my granddaughter. They competed against 300+ FIRST LEGO League (FLL)Challenge teams in Massachusetts and finished first place in the MA FLL East State Championship event of December 2023 to represent Massachusetts State at the World Festival.

At the World Festival, Goofy Gyros was recognized with two awards for their performance—Core Values Finalist Award and Inspire Team Award (a peer recognized award).

What is the connection of ET with the work of Goofy Gyros? For the 2023 FIRST LEGO competition, the team decided to make a device to help individuals who cannot do what they desire to do because of hand tremors. The student innovators called their device -the Multi-component Assistive Smart TrEmor Reducer (MASTER). They spoke to the staff of International Essential Tremor Foundation during a ZOOM call, responded to their queries and presented a prototype to many entrepreneurs and experts from industry. They encouraged the team and gave positive reviews.

“The MASTER prototype incorporates six different techniques which can collectively reduce hand tremors. It is potentially scalable for a variety of uses and can be produced inexpensively.” TREMOR TALK, a publication of the International Essential Tremor Foundation in its printed issue 44 June 2024 described the prototype in a Feature article titled“STUDENT INNOVATORS”.

Hearty congratulations to Goofy Gyros and its mentors.