Essential Tremor

Overview

The most common movement disease, essential tremor, is a sickness of uncertain cause that is defined by a slowly increasing postural and/or kinetic tremor that generally affects both upper extremities. There is much disagreement on whether essential tremor is a neurodegenerative illness.

Tremors of the head, voice, or lower limbs may accompany it. Essential tremor is frequently present for years or decades before symptoms appear, and it advances slowly. It is frequently familial and only temporarily sensitive to alcohol. Propranolol and primidone, which are synergistic, are the two first-line drugs for individuals who require therapy. Deep brain stimulation or targeted ultrasound are options for patients with debilitating essential tremor that cannot be treated therapeutically.

Tremor

Tremor is a rhythmic and oscillatory involuntary movement of a bodily part with a generally constant frequency and varying amplitude. It is caused by antagonistic muscles contracting alternately. Tremor is the most prevalent movement condition, and the most frequent neurologic cause of postural or action tremor is essential tremor. It often manifests as a bilateral postural 6 to 12 Hz hand tremor, followed by a kinetic and resting component.

The upper limbs are frequently symmetrically implicated, but as the disease progresses, the head and voice (and, less frequently, the legs, jaw, face, and trunk) may become involved. Although it has a little impact on life expectancy, it frequently causes humiliation and, in a tiny number of patients, substantial impairment. Symptoms are usually progressive and possibly crippling, causing individuals to shift careers or retire early.

What is an essential tremor?

Essential tremor (ET) is a neurological illness that produces rhythmic shaking of your hands, head, torso, voice, or legs. It is frequently mistaken for Parkinson's disease. The most prevalent shaking ailment is essential tremor. Everyone has some degree of tremor, although the motions are normally imperceptible since the tremor is so little. Essential tremor is a condition in which tremors are visible.

Epidemiology

The most prevalent neurologic condition affecting postural or movement tremors is essential tremor. The global prevalence is believed to be up to 5% of the population. Nearly half of all cases have a family history, and monozygotic twins have a 90 percent concordance rate. Although the frequency of essential tremor increases with age, it frequently affects young people, especially when it is familial.

The frequency and incidence of essential tremor varies greatly depending on the methods and diagnostic criteria used to diagnose the disorder. The prevalence of essential tremor in the general population is estimated to be 0.3-5.6 percent. Both sexes are equally affected by essential tremor. Head tremor, on the other hand, may be more common in women, while postural hand tremor, on the other hand, may be more severe in males. Boys may be more prone to essential tremor in childhood than girls.

Causes of essential tremor

The cause of essential tremor is unknown. There are no pathologic signs that are consistently related with essential tremor. However, the following hypotheses have been proposed:

Essential tremor is the result of an abnormally functioning central oscillator, which is located in the Guillain Mollaret triangle near the brainstem and involves the inferior olivary nucleus
The cerebellar-brainstem-thalamic-cortical circuits probably are involved
The pathophysiology of essential tremor is heterogeneous

Genetics

Essential tremor is most likely a condition, and numerous etiologies will be uncovered. The majority, if not all, of these factors are most likely hereditary. In at least 50-70 percent of instances, essential tremor is inherited. The inheritance pattern is autosomal dominant, with imperfect penetrance. Some occurrences are sporadic and have an unclear cause. Twin studies indicate that genetic and environmental variables have a role in pathogenesis. One study found non-Mendelian transmission of essential tremor in families with an apparent autosomal dominant inheritance.

The large discrepancy in findings can be attributed to differences in technique (e.g., evaluation processes and diagnostic criteria); published studies have revealed that 17 percent to nearly 100 percent of cases are familial. Following frequent and diverse questioning followed by direct interviews of family members, the frequency of having an afflicted relative increased from 67.7 percent to 96 percent.

Pathophysiology

According to some accounts, the neuropathology of essential tremor is concentrated in the brainstem (locus coeruleus) and cerebellum, however the prevalence of cerebellar pathology is debatable. However, essential tremor is thought to be a risk factor for the development of Parkinson disease. Furthermore, there has been a link discovered between essential tremors and dystonic movements.

It has been proposed that essential tremor is a risk factor for the development of Parkinson disease. Some Parkinson's disease patients have a lengthy history of bilateral upper extremity postural tremor. Furthermore, the incidence of essential tremor was considerably higher among relatives of patients with Parkinson disease with earlier start and in relatives of patients with tremor-predominant Parkinson disease.

However, without biologic markers for both disorders, it is impossible to tell if long-standing postural tremor is part of a Parkinson disease syndrome or indicates the existence of both essential tremor and Parkinson disease. A link between essential tremor and dystonia has also been proposed. Mild, bilateral upper extremity postural tremors are seen in some patients with focal dystonia, such as torticollis. However, without biologic markers for both disorders, it is impossible to determine whether postural tremor is part of a localized dystonia syndrome or indicates the existence of both dystonia and essential tremor.

Essential tremor symptoms

Essential tremor most commonly affects the hands and arms bilaterally and is symmetric; however, examples of asymmetric essential tremor have been described. The tremor was more severe in the non-dominant arm in patients of asymmetric essential tremor. It can also affect the head and voice, as well as the face, legs, and trunk in rare cases. It ranges from a low amplitude, high-frequency postural tremor of the hands to a considerably bigger amplitude, a tremor triggered by certain postures and movements. The tremor frequency of essential tremor is usually 6 to 12 Hz.

When the arms are kept extended, essential tremor is visible; it often develops towards the completion of goal-directed actions such as drinking from a glass or finger-to-nose testing. Amplitude increases with age, whereas frequency decreases with age. Despite considerable differences in tremor amplitude and impairment among people with essential tremor, it is a debilitating disorder for a significant number of those affected.

A number of studies have found that the amplitude of kinetic tremor in the upper limbs is related to functional impairment in essential tremor. Some people with essential tremor experience increased physiologic tremor as a result of worry or other adrenergic processes, exacerbating the underlying tremor.

During a physical examination, essential tremor can be triggered in two ways: with the arms hung against gravity in a fixed position and during goal-directed activity. Essential tremor is frequently eased by modest doses of alcohol (60-70%) but, unlike physiologic tremor, is not usually exacerbated by coffee. Additional cerebellar symptoms, such as aberrant tandem walking and moderate ataxia, can be detected in certain patients.

With essential tremor, trembling in the legs is rare. If the resting tremor is present in the legs, Parkinsonian tremor is more prevalent. In essential tremor, a tremor of the head occurs infrequently. When this occurs, cervical dystonia with dystonic head tremor should be investigated.

Preliminary research also suggests that patients with essential tremor may have more mild cognitive deficits, with lower performance on memory and frontal executive function tests, than age-matched controls, and that essential tremor may be associated with an increased risk of dementia and Parkinson disease.

Benign essential tremor

Benign essential tremor (ET) is a movement disease that causes uncontrollable shaking. It can affect any region of the body, although the hands are the most commonly affected. The doctor will inquire about your symptoms and medical history. A physical examination will be performed. A neurological examination may also be performed. The tremor will be visible to the doctor. This is sufficient information to make a diagnosis.

Diagnosis

The clinical symptoms and exclusion of alternate diagnoses are used to make the diagnosis of essential tremor. The basic criteria need a bilateral action tremor of the hands and forearms as well as the absence of any neurologic symptoms. Other factors that strongly support essential tremor include a lengthy duration of the tremor (more than 3 years), a positive family history of essential tremor, and a favourable response to alcohol.

A complete neurologic examination is used to determine particular aspects of the tremor, such as its frequency, amplitude, pattern, and distribution, as well as other neurologic abnormalities that may be present. Caffeine, alcohol, medicines, exercise, weariness, or stress should be elicited as precipitating, exacerbating, or relieving variables; a thorough list of all drugs should be checked to rule out the potential of heightened physiologic tremor.

There are no particular biomarkers or results from neuroimaging or other ancillary investigations that can be used to confirm the diagnosis of essential tremor, however testing may be necessary to rule out alternative causes of tremor. Thyroid function, urinary copper, and ceruloplasmin tests may be performed to rule out Wilson disease, as well as screening for heavy metal toxicity such as lead if any of these causes is suspected.

Brain imaging can be helpful in individuals who are clinically suspected of having a structural explanation for their tremors, such as Wilson disease, brain trauma, stroke, or mass lesion, although it is not always necessary. Striatal dopamine transporter imaging with ioflupane I123 injection single-photon emission tomography can reliably differentiate patients with Parkinson disease and other parkinsonian syndromes associated with nigrostriatal degeneration, such as multiple system atrophy, progressive supranuclear palsy, and corticobasal degeneration, from those with essential tremor.

Essential tremor treatment

Patients who are less affected may choose to forego therapy entirely. Some patients who are not functionally disabled want therapy since their tremor is a source of embarrassment for them. Non-medical, medical, or interventional treatment are options for people with considerable functional impairment.

Non-Medical Therapy

Tremors can be alleviated in some people by weighing the limb, commonly using wrist weights. This can give some alleviation or enhance functionality in a small percentage of people. Because worry and stress are known to aggravate tremors, non-medical relaxation methods and biofeedback can be beneficial in certain individuals. Medications that are known to aggravate tremors should be avoided or reduced if feasible.

People who have tremors may also benefit from eliminating stimulants in their diet, such as coffee. There are numerous commercially available technologies to assist stabilize the use of utensils, such as weighted utensils or active cancelation of tremor technology, which might be beneficial for some patients.

Medical Therapy

The treatment of essential tremor is frequently trial and error, and patients should be challenged by numerous drugs if the initial option is inadequate or linked with unpleasant side effects. There are three types of medical treatment: first-line, second-line, and third-line.

First-line treatment is either FDA-approved or supported by double-blind, placebo-controlled trials that fulfill class I evidence requirements. Propranolol and primidone are examples of drugs in this class. If both primidone and propranolol are ineffective on their own, combinations of the two may give relief in some people.
Second-line treatment is supported by double-blind, placebo-controlled trials that do not fulfill the other criteria for class I evidence studies. Gabapentin, pregabalin, topiramate, benzodiazepines (clonazepam, alprazolam), beta-blockers (atenolol and metoprolol), and zonisamide are examples of such medications.
Third-line therapy: These treatments are based on open-label research or case reports. This family of drugs includes nimodipine and clozapine.

Interventional Therapy

Focused ultrasound, or radio-surgical gamma knife thalamotomy, deep brain stimulation (DBS) and Injections of botulinum neurotoxin are surgical alternatives for individuals who have failed to respond to pharmaceutical therapy or cannot handle the negative effects of the above medications.

Injections of botulinum neurotoxin (BoNT): In certain individuals with severe head or hand tremors, injections of botulinum toxins can be beneficial. BoNT should be investigated as a therapy option for essential hand tremor in individuals who have failed to respond to oral medicines.

Deep-brain stimulation: The most frequent surgical therapy for essential tremor is this. The majority of studies indicate control of hand tremors of 70% to 90%. Deep-brain stimulation involves delivering electrical stimulation to the brain through an electrode placed deep into the ventral intermediate nucleus (VIM) of the thalamus. This is normally accomplished by stereotactically implanting four electrodes in the VIM. After the patient leaves the hospital, computerized programming of the pulse generator is most typically done using a portable device to optimize the electrode montage, voltage, pulse frequency, and pulse width. Depending on the patient's symptoms, deep brain stimulation can be performed unilaterally or bilaterally. With bilateral surgeries, there is an increased chance of speech and balance issues. If the tremor affects both hands considerably and the dominant hand is targeted, bilateral operations may be explored.

Thalamotomy: Stereotactic surgical techniques can create a lesion in the ventral intermediate (VIM) nucleus of the thalamus.

Focused ultrasound: Magnetic resonance imaging-guided, high-intensity, targeted ultrasonic thalamotomy, approved by the FDA in 2016, is a novel approach for treating essential tremor. Despite the fact that it is transcranial and does not necessitate an incision, skull penetration, or an implanted device, it is an invasive therapy that results in a permanent thalamic lesion.

Radio-surgical gamma knife thalamotomy: Gamma-knife thalamotomy focuses high-energy gamma rays on the ventral intermediate, causing neuron death. It is an untested therapy that has not been widely embraced because to worries about potential radiation adverse effects, such as the speculative long-term danger of secondary tumor growth.

Differential Diagnosis

Conditions to consider in the differential diagnosis of essential tremor include the following:

Physiologic tremor: Action tremor that is predominantly bilateral and symmetrical. The existence of a recognized cause and a high frequency (10 to 12 Hz) (e.g., medications, hyperthyroidism, hypoglycemia)
Parkinson Disease Tremor: Predominantly at rest, asymmetrical. Usually does not produce head tremor. Frequency 4 to 6 Hz.
Orthostatic tremor: Postural tremor in the torso and lower limbs when standing; upper limbs may also be affected. Walking suppresses. Tremor has a high frequency (14 to 20 Hz) and is synchronized between the ipsilateral and contralateral muscles.
Cerebellar tremor: Postural, intention, or action tremor. Relatively low frequency (3 to 4 Hz). Associated with ataxia and dysmetria.
Writing tremor (task-specific): Not visible in other jobs that need coordination, except when writing. It is thought to be a kind of focal hand dystonia (writer's cramp).
Psychogenic tremor: The degree of symptoms varies based on the subject's emotional condition as a result of stressful life experiences. Sudden start and spontaneous remission, higher amplitude and frequency changes, and less severity are all important indicators to distinguish the psychogenic nature. Distractions such as alternate finger tapping, mental concentration on serial 7s, or a healthcare professional placing a vibrating tuning fork on a patient's forehead and informing the patient that this will stop the tremor and entrainment disappear the tremors. Entrainment occurs when the tremor frequency changes in response to voluntary movements, such as a regular movement in the contralateral limb.

Essential tremor vs Parkinson's disease

Parkinson's disease does not impair the vocal box, whereas essential tremor does. Essential tremors are often felt more when moving, whereas Parkinson's tremors are sensed more when resting. Essential tremor symptoms might worsen with time, although they do not inevitably shorten the patient's life.

Prognosis

Despite the lack of prospective longitudinal evidence, essential tremor usually progresses slowly and steadily. In a small percentage of individuals, essential tremor might be stable. However, rather than an essential tremor, a consistent course should raise concern for an alternate diagnosis such as an increased, physiologic tremor or drug-induced tremor. Essential tremors may be linked to an increased risk of Parkinson's disease, notwithstanding the lack of prospective research. The survival rate of people with essential tremor is similar to that of the general population. The general standard of living is deplorable.

Conclusion

Essential tremor is a disease that does not have a cure. Even while it isn't life-threatening, it can cause a lot of discomfort and make it difficult to operate. There have even been studies that show it may cause Parkinson's disease or dystonia. Because there are so many different therapies for essential tremor, it's ideal to manage it with the help of a multidisciplinary team.

The most important step is to educate the patient about the illness and how to treat it. Only observation is suggested for people who are not affected by the disease. For essential tremor, there are medicinal and non-medical treatments available, however there is no evidence to favor one over the other. The pharmacists should inform the patient about the many types of medications available, as well as their adverse effects and advantages.

Because vital tremors are influenced by stress and exercise, patient education is critical. Caffeinated drinks, alcohol, and stress should be avoided by the patient.

Many patients get nervous, unhappy, and ashamed as a result of their illness, and they withdraw as a result. As a result, a mental health nurse consultation is required. Because the illness is familial, a social worker's follow-up with family members is critical. The optimal therapy and outcomes for these patients will come from an interdisciplinary team of nurses, pharmacists, and physicians.