Essential Tremor: Difference between revisions

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<div class="editorbox"> '''Original Editor '''- [[User:Jonathan_de_Leyer |Jonathan De Leyer]], [[User:Brooke_Eveleigh|Brooke Eveleigh]], [[User:Kyrie_Hicks|Kyrie Hicks]], [[User:Peter_Kmiecik|Peter Kmiecik]], [[User:Julie_Walden|Julie Walden]] as part of the [[Queen's University Neuromotor Function Project]]
'''Original Editor '''- [http://www.physio-pedia.com/User:Jonathan_de_Leyer Jonathan De Leyer]  
'''Top Contributors''' - {{Special:Contributors/{{FULLPAGENAME}}}}</div>
== Introduction  ==
[[File:Spiral drawing - essential tremor.jpeg|thumb|Spirals drawn by a patient with unilateral ET ]]
Essential tremor (ET) is classified as a [[Neurological Disorders|neurological disorder]]. It usually presents as a bilateral postural (6 to 12 Hz) tremor of the hands, followed by a kinetic and resting component. The upper limbs are often symmetrically involved, but with ET progression, the head and voice (less often legs, jaw, face, and trunk) might be involved. Despite the fact that is is benign in respect to its effect on life expectancy, it often causes embarrassment and, in a tiny percentage of patients, also serious disability. Symptoms are typically progressive and potentially disabling, for example it may force patients to change jobs or seek early retirement. The key is first to educate the patient on the disorder and its treatment.<ref name="Abboud, H, Ahmed, A., & Fernandez, HH">Abboud, H., Ahmed, A., Fernandez, HH. Essential tremor: choosing the right management plan for your patient. Cleve Clin J Med 2011;78(12):821-8.</ref><ref name=":0">Agarwal S, Biagioni MC. Essential tremor. InStatPearls [Internet] 2021 Jul 12. StatPearls Publishing. Available:https://www.ncbi.nlm.nih.gov/books/NBK499986/ (accessed 15.9.2022)</ref>


'''Lead Editors'''&nbsp;- [http://www.physio-pedia.com/User:Brooke_Eveleigh Brooke Eveleigh], [http://www.physio-pedia.com/User:Kyrie_Hicks Kyrie Hicks], [http://www.physio-pedia.com/User:Peter_Kmiecik Peter Kmiecik], [http://www.physio-pedia.com/User:Julie_Walden Julie Walden]
== Etiology ==
<br></div>
The etiology of essential tremor is not known. About 50% of the cases of ET appear to result from a [[Genetics and Health|genetic]] mutation (no specific gene has been identified), and is is referred to as familial tremor. The lack of consistency of age of onset, the presence of sporadic cases, and incomplete concordance of essential tremor among monozygotic twins leads to the view that environmental factors play a role.
== Introduction<ref name="Abboud, H, Ahmed, A., & Fernandez, HH">Abboud, H., Ahmed, A., Fernandez, HH. Essential tremor: choosing the right management plan for your patient. Cleve Clin J Med 2011;78(12):821-8.</ref><br>  ==


Essential tremor (ET) is classified as a neurological disorder. It is commonly characterized as an uncontrollable shaking that occurs in various body parts, such as the head, chin, hands, arms, and also presents with a shaking voice due to affected vocal cords. ET is different from a resting tremor, which is associated with Parkinson’s, and is commonly classified as an action tremor.<br>
The Movement Disorders Society diagnostic criteria include:


== Mechanism of Injury / Pathological Process<ref name="Louis 2001">Louis, E.D., Essential tremor. The New England Journal of Medicine 2001;345:887-891.</ref><br>  ==
# Tremor is bilateral, symmetrical, and postural
# The tremor involves the forearms and hand
# Is persistent and visible
# It may be associated with isolated head tremor<ref name=":0" />


The likelihood of acquiring ET has been shown to increase with age, in different ethnicities, and in persons with a family history of ET. The risk of acquiring ET has been shown to be more prevalent in older populations. An increased risk has also been found in Caucasians opposed to African-American populations.  
== Epidemiology ==
ET is considered to be one of the most, if not the most, common adult movement disorders<ref name="Louis, Ford, Lee, Andrews">Louis ED, Ford B, Lee H, Andrews H. Does a screening questionnaire for essential tremor agree with the physician’s examination? Neurology 1998;50:1351–1357 DOI: http://dx.doi.org/10.1212/WNL.50.5.1351</ref>. The worldwide estimated prevalence is up to 5% of the population. Family history can be found in near 50% of cases. The incidence of essential tremor increases with age, however it often affects young individuals, mainly when it is familial.<ref name=":0" />


Genetic factors have been linked to increased prevalence of ET with some studies suggesting potential linkages identified at the 3q13 and 2p22 chromosomes. However, there is a large discrepancy if genetic factors are a cause of ET, since other studies found only a moderate link (60-63%) in monozygotic twins and a low link (27-42%) in dizygotic twins. This is indicative that environmental factors likely play a role in the prevalence of ET's. A link in β-carboline alkaloids (harmine and harmane) has been found in subjects with ET, since high concentrations of β-carboline alkaloids were found in their blood.  
== Diagnosis ==
There are no special tests for diagnosing essential tremor. The doctor will usually make a diagnosis after a detailed neurologic examination to identify specific features of the tremor.  


β-carboline alkaloids are found in high meat diets and increased meat consumption has been linked with prevelance in persons with ET. An increased concentration of lead was also found in subjects with ET's. These environmental factors increase the risk for developing ET, and the risk of aquring ET increases when gentetics, age, and ethnicity of the person favourable ET development<span style="font-size: 11px;">.</span><br>  
The core criteria require either a bilateral action tremor of the hands and forearms and the absence of other neurologic signs. Other information strongly suggestive of essential tremor includes long duration (more than 3 years) of the tremor, a positive family history of essential tremor, and beneficial response to [[Stress and Health|stress]] reduction.<ref name=":0" />  


== Epidemiology  ==
== Clinical Presentation  ==
 
ET is considered to be one of the most, if not the most, common adult movement disorders<ref name="Louis, Ford, Lee, Andrews">Louis ED, Ford B, Lee H, Andrews H. Does a screening questionnaire for essential tremor agree with the physician’s examination? Neurology 1998;50:1351–1357 DOI: http://dx.doi.org/10.1212/WNL.50.5.1351</ref>. It is estimated to affect 0.9% of the population worldwide<ref name="Louis, E.D., Ferreira, J.J.">Louis, E.D., Ferreira, J.J. How common is the most common adult movement disorder? Update on the worldwide prevalence of essential tremor. Movement Disorders, 2010;25(5):534-541. DOI: 10.1002/mds.22838</ref>. The prevalence increases greatly with age, it is estimated to reach an average of 4.6% in the population over 65 years of age<ref name="Louis, E.D., Ferreira, J.J." />. Additionally, more recent studies indicate the potential of a slightly higher prominence of the condition in men than women<ref name="Louis, E.D., Ferreira, J.J." />. Finally, it is thought that further research could indicate differences in prevalence among different ethnic groups<ref name="Louis, E.D., Ferreira, J.J." />.<br>
 
== Diagnostic Procedures  ==
 
The literature is somewhat variable on the method of diagnosis of ET. This is due to varied clinical presentations and a lack of agreement among specialists on the definition of ET<ref name="Jain 2006">Jain S, Lo SE, Louis ED. Common misdiagnosis of a common neurological disorder: how are we misdiagnosing essential tremor? Arch Neurol 2006;63:1100–1104.</ref>. Despite variability and an inability to test for serological, pathological or radiological markers as a method of diagnosis, there are several clinical criteria which are used to differentiate tremor types<ref name="Bhidiyasiri">Bhidayasiri, R. Differential diagnosis of common tremor syndromes. Postgrad Med J 2005;81:756-762. DOI: 10.1136/pgmj.2005.032979</ref>. This clinical examination is very comprehensive and typically includes the following observations or tests<ref name="Bhidiyasiri" />:<br>
 
*Observe the patient at rest and note any resting tremor or the head, hands or leg
*Ask the patient to stretch out arms to observe for postural tremor
*Check finger-nose-finger movements to observe kinetic tremor
 
On assessment of ET, there should be no findings of any other focal neurological condition. A diagnosis of definite ET includes the following clinical criteria<ref name="Bhidiyasiri" />:<br>
 
#Postural tremor of moderate amplitude is present in a least one arm (although usually bilateral)
#Tremor of moderate amplitude is present in at least one arm during at least four tasks<br>a. Pouring water<br>b. Using a spoon to drink water<br>c. Finger-nose-finger maneuver<br>d. Drawing a spiral
#Tremor must interfere with at least one activity of daily living (ADL)
#Medications, hypothyroidism, alcohol use and other neurological conditions are not the cause of the tremor
 
The clinical criteria used for a “probably ET” are listed as follows<ref name="Bhidiyasiri" />:
 
#Tremor of moderate amplitude is present in at least one arm during at least four tasks, or head tremor is present
#Medications, hyperthyroidism, alcohol use and other neurological conditions are not the cause of the tremor
 
Any of the following objective findings which would indicate a tremor diagnosis other than ET: abnormal neurological exam findings, isolated voice tremor, isolated positon-specific or task-specific tremor and isolated tongue, chin or leg tremor<ref name="Bhidiyasiri" />. Tremors associated with Parkinson’s Disease (PD) can be difficult to differentiate from ET. Key features such as asymmetric onset, resting tremor and a tremor while walking would indicate a parkinsonian origin and not ET<ref name="Bhidiyasiri" />.
 
Screening questionnaires can be used for diagnosis of ET but the generally only have a moderate (60-70%) sensitivity <ref name="Louis, Ford, Lee, Andrews" /><ref name="Benito-Leon">Benito-Leon J, Bermejo-Pareja F, Louis ED. Incidence of essential tremor in three elderly populations of central Spain. Neurology 2005;64:1721–1725.</ref>&nbsp;Responses to these questionnaires generally correlated well to the clinical examination findings for those with definite or probably ET. Subjects with a diagnosis of mild ET from a clinical examination were most often screened as negative on the questionnaires&nbsp;<ref name="Louis, Ford, Lee, Andrews" />.<br><br>
 
== Clinical Presentation<br> ==


Essential tremor primarily presents as a kinetic tremor of the upper extremities, meaning it appears when we move throughout our various daily activities<ref name="Louis 2006">Louis, E. D. (2006). Essential tremor. Clinics in Geriatric Medicine, 22(4), 843-857. doi:10.1016/j.cger.2006.06.012</ref><ref name="Louis 2005">Louis, E. D. Essential tremor. Lancet Neurology, 2005;4(2),100-110. doi:10.1016/S1474-4422(05)00991-9</ref>. The tremor typically oscillates between 4 and 12 Hz, with the frequency of the tremor being inversely proportional to one’s age <ref name="Brennan">Brennan, K. C., Jurewicz, E. C., Ford, B., Pullman, S. L., &amp; Louis, E. D. Is essential tremor predominantly a kinetic or a postural tremor? A clinical and electrophysiological study. Movement Disorders, 2002;17(2):313-316. doi:10.1002/mds.10003</ref><ref name="Deuschl">Deuschl, G., Bain, P., &amp; Brin, M. Consensus statement of the movement disorder society on tremor. Movement Disorders, 1998;13(S3):2-23. doi:10.1002/mds.870131303</ref>. The tremor may also present as intention tremor, increasing in magnitude and frequency as the patient voluntarily moves their arm or hand closer to specific objects or points<ref name="Louis 2006" />.  
Essential tremor primarily presents as a kinetic tremor of the upper extremities, meaning it appears when we move throughout our various daily activities<ref name="Louis 2006">Louis, E. D. (2006). Essential tremor. Clinics in Geriatric Medicine, 22(4), 843-857. doi:10.1016/j.cger.2006.06.012</ref><ref name="Louis 2005">Louis, E. D. Essential tremor. Lancet Neurology, 2005;4(2),100-110. doi:10.1016/S1474-4422(05)00991-9</ref>. The tremor typically oscillates between 4 and 12 Hz, with the frequency of the tremor being inversely proportional to one’s age <ref name="Brennan">Brennan, K. C., Jurewicz, E. C., Ford, B., Pullman, S. L., &amp; Louis, E. D. Is essential tremor predominantly a kinetic or a postural tremor? A clinical and electrophysiological study. Movement Disorders, 2002;17(2):313-316. doi:10.1002/mds.10003</ref><ref name="Deuschl">Deuschl, G., Bain, P., &amp; Brin, M. Consensus statement of the movement disorder society on tremor. Movement Disorders, 1998;13(S3):2-23. doi:10.1002/mds.870131303</ref>. The tremor may also present as intention tremor, increasing in magnitude and frequency as the patient voluntarily moves their arm or hand closer to specific objects or points<ref name="Louis 2006" />.  


Although primarily located in the arms, essential tremor may gradually spread in a somatotrophic fashion to other parts of the body such as the head or voice, or less commonly the lower extremities<ref name="Louis 2005" />. Patients experiencing more severe or farther progressed essential tremor may present with additional postural tremor or may be disabled in their ability to perform activities of daily living (ADLs) such as eating and dressing<ref name="Brennan" /><ref name="Louis 2006" />. Essential tremor presents with a larger set of additional characteristics than initially thought<ref name="Louis 2006" />. These include motor features such as signs of cerebellar dysfunction and tremor at rest, as well as non-motor features such as cognitive deficits and personality changes<ref name="Louis 2006" /><ref name="Brennan" />.<br><br>
Although primarily located in the arms, essential tremor may gradually spread in a somatotrophic fashion to other parts of the body such as the head or voice, or less commonly the lower extremities<ref name="Louis 2005" />. Patients experiencing more severe or farther progressed essential tremor may present with additional postural tremor or may be disabled in their ability to perform activities of daily living ([[Activities of Daily Living|ADLs]]) such as eating and dressing<ref name="Brennan" /><ref name="Louis 2006" />. Essential tremor presents with a larger set of additional characteristics than initially thought<ref name="Louis 2006" />. These include motor features such as signs of [[Cerebellum|cerebellar]] dysfunction and tremor at rest, as well as non-motor features such as [[Cognitive Impairments|cognitive deficits]] and personality changes<ref name="Louis 2006" /><ref name="Brennan" />.


== Management / Interventions<br>  ==
== Medical Management ==
Less impaired patients may choose no treatment. Some patients that are not functionally impaired desire treatment because their tremor causes social embarrassment. Options for patients with significant functional impairment include non-medical, medical, or interventional therapy.


'''Physical therapy treatment''' for ET primarily focuses on resistance training. Typically, this is done on the upper extremity to improve strength and coordination, and to reduce tremor severity. Six weeks of resistance training using bicep curls, wrist flexion and extension has been shown to improve these outcome measures<ref name="Kavanagh 2016">Kavanagh, J.J., Wedderburn-Bisshop, J., Keogh, J.W.L. Resistance training reduces force tremor and improves manual dexterity in older individuals with essential tremor. Journal of Motor Behavior 2016;48(1):20-30. DOI: 10.1080/00222895.2015.1028583</ref><ref name="Sequiera 2012">Sequiera, G., Keogh, J.W., Kavanagh, J.J. Resistance training can improve fine manual dexterity in essential tremor patients: A preliminary study. Archives of Physical Medicine and Rehabilitation 2012;93(8):1466-1468. DOI: 10.1016/j.apmr.2012.02.003</ref>. Even performing isometric loads on the index finger reduces pointing variability for patients with ET<ref name="Bilodeau 2000">Bilodeau, M., Keen, D.A., Sweeney, P.J., Shields, R.W., &amp; Enoka, R.M. Muscle &amp; Nerve 2000;23(5):771-778. DOI: 10.1002/(SICI)1097-4598(200005)23:5&amp;lt;771::AID-MUS15&amp;gt;3.0.CO;2-9</ref>.&nbsp;In addition to resistance training, behavioral relaxation therapy has been shown to decrease the tremor severity. Behavioral relaxation involves putting the patient into a relaxed position using a ten-step progression. This is done because stress has been shown to increase the severity of tremors<ref name="Lundervold 2004">Lundervold, D.A., Poppen, R. Biobehvioural intervention for older adults with essential tremor. Applied Psychophysiology and Biofeedback 2004;29(1):63-73. DOI: 10.1023/B:APBI.0000017864.06525.eb</ref>.  
# '''Non medical therapy.''' For some patients, tremors can be reduced by weighting the limb, typically by applying wrist weights (this dampening the tremor enough to provide some relief or improve functioning for a few patients). Since anxiety and stress make the tremor worse, non-medical [[Relaxation Techniques|relaxation]] techniques and [[biofeedback]] may help some patients. Medications known to make tremors worse should be eliminated or reduced if possible. People with ED may possibly benefit from avoiding dietary stimulants, for example [[Caffeine and Exercise|caffeine]]. Also commercially available technologies eg weighted utensils, may be helpful for some patients.<ref name=":0" />
# '''Pharmacological treatment''' for ET has shown some promising results. Propranolol and primidone are the most commonly used drugs. They have around a 50 - 70% effectiveness in patients. However, there are some side effects such as dizziness, nausea, fast or slow [[Heart Rate|heart beat]], and drowsiness among others<ref name="Witjas 2016">Witjas, T., Carron, R., Boutin, E., Eusebio, A., Auzulay, J.P., Régis, J. Essential tremor: Update of therapeutic strategies (medical treatment and gamma knife thalamotomy. Revue Neurologique 2016;172(8-9):408-415. DOI: 10.1016/j.neurol.2016.07.014</ref>. Topiramate is an alternative medication used for ET and is often used when the previous two are ineffective. It is effective in about 22-37% of patients. A recent systematic review by Bruno et al 2017 found that while effective, more studies are still needed to determine its efficacy and safety<ref name="Bruno 2017">Bruno, E., Nicoletti, A., Quattrocchi, G., Allegra, R., Fillippini, G., Colsimo, C., Zappia, M. Topiramate for essential tremor. Cochrane Reviews 2017. DOI: 10.1002/14651858.CD009683.pub2</ref>.
# Two main types of '''surgical techniques''' are used for essential tremor, [[Deep Brain Stimulation|deep brain stimulation]] and thalamotomy. Deep brain stimulation (DBS) was originally used for treating [[Parkinson's|Parkinson’s Disease]] but has been us to treat ET as well. It involves implanting electrodes in the thalamus in the ventral intermediate nucleus. These are then connected to a pulse generator typically located behind the clavicle. When it is turned on it stimulates the thalamus reducing the tremor. It can be turned on and off at the patients discretion. A systematic review in 2010 found that DBS significantly improved outcomes in patients with ET. Moreover, any mild adverse effects they produced were reduced by modulating the pulse of the deep brain stimulation<ref name="Della Flora 2010">Della Flora, E., Perera, C.L., Cameron, A.L., Maddern, G.J. Deep brain stimulation for essential tremor: A systematic review. Movement Disorders 2010;25(11):1550-1559. PMID: 20623768</ref>.<br>Thalamotomy involves lesioning the portions of the thalamus that cause the tremors. Different types include radiofrequency thalamotomy, laser induced thermal therapy, magnetic resonance guided focused ultrasound, focused thermolesions and gamma knife thalamotomy. They essentially do the same thing but due to different procedures some are associated with higher risks<ref name="Witjas 2016" />.


<br>'''Pharmacological treatment''' for ET has shown some promising results. Propranolol and primidone are the most commonly used drugs. They have around a 50 - 70% effectiveness in patients. However, there are some side effects such as dizziness, nausea, fast or slow heart beat, and drowsiness among others<ref name="Witjas 2016">Witjas, T., Carron, R., Boutin, E., Eusebio, A., Auzulay, J.P., Régis, J. Essential tremor: Update of therapeutic strategies (medical treatment and gamma knife thalamotomy. Revue Neurologique 2016;172(8-9):408-415. DOI: 10.1016/j.neurol.2016.07.014</ref>. Topiramate is an alternative medication used for ET and is often used when the previous two are ineffective. It is effective in about 22-37% of patients. A recent systematic review by Bruno et al 2017 found that while effective, more studies are still needed to determine its efficacy and safety<ref name="Bruno 2017">Bruno, E., Nicoletti, A., Quattrocchi, G., Allegra, R., Fillippini, G., Colsimo, C., Zappia, M. Topiramate for essential tremor. Cochrane Reviews 2017. DOI: 10.1002/14651858.CD009683.pub2</ref>.
== Physical Therapy Management  ==


<br>Two main types of '''surgical techniques''' are used for essential tremor, deep brain stimulation and thalamotomy. Deep brain stimulation (DBS) was originally used for treating Parkinson’s Disease but has been us to treat ET as well. It involves implanting electrodes in the thalamus in the ventral intermediate nucleus. These are then connected to a pulse generator typically located behind the clavicle. When it is turned on it stimulates the thalamus reducing the tremor. It can be turned on and off at the patients discression. A systematic review in 2010 found that DBS significantly improved outcomes in patients with ET. Moreover, any mild adverse effects they produced were reduced by modulating the pulse of the deep brain stimulation<ref name="Della Flora 2010">Della Flora, E., Perera, C.L., Cameron, A.L., Maddern, G.J. Deep brain stimulation for essential tremor: A systematic review. Movement Disorders 2010;25(11):1550-1559. PMID: 20623768</ref>.<br>Thalamotomy involves lesioning the portions of the thalamus that cause the tremors. Different types include radiofrequency thalamotomy, laser induced thermal therapy, magnetic resonance guided focused ultrasound, focused thermolesions and gamma knife thalamotomy. They essentially do the same thing but due to different procedures some are associated with higher risks<ref name="Witjas 2016" />.  
Physical therapy treatment for ET primarily focuses on [[Strength Training|resistance training.]] Typically, this is done on the upper extremity to improve strength and [[Coordination Exercises|coordination]], and to reduce tremor severity. Six weeks of resistance training using [[Biceps Brachii|bicep]] curls, wrist flexion and extension has been shown to improve these outcome measures<ref name="Kavanagh 2016">Kavanagh, J.J., Wedderburn-Bisshop, J., Keogh, J.W.L. Resistance training reduces force tremor and improves manual dexterity in older individuals with essential tremor. Journal of Motor Behavior 2016;48(1):20-30. DOI: 10.1080/00222895.2015.1028583</ref><ref name="Sequiera 2012">Sequiera, G., Keogh, J.W., Kavanagh, J.J. Resistance training can improve fine manual dexterity in essential tremor patients: A preliminary study. Archives of Physical Medicine and Rehabilitation 2012;93(8):1466-1468. DOI: 10.1016/j.apmr.2012.02.003</ref>. Even performing isometric loads on the index finger reduces pointing variability for patients with ET<ref name="Bilodeau 2000">Bilodeau, M., Keen, D.A., Sweeney, P.J., Shields, R.W., &amp; Enoka, R.M. Muscle &amp; Nerve 2000;23(5):771-778. DOI: 10.1002/(SICI)1097-4598(200005)23:5&amp;lt;771::AID-MUS15&amp;gt;3.0.CO;2-9</ref>.&nbsp;In addition to resistance training, behavioral relaxation therapy has been shown to decrease the tremor severity. Behavioral relaxation involves putting the patient into a relaxed position using a ten-step progression. This is done because stress has been shown to increase the severity of tremors<ref name="Lundervold 2004">Lundervold, D.A., Poppen, R. Biobehvioural intervention for older adults with essential tremor. Applied Psychophysiology and Biofeedback 2004;29(1):63-73. DOI: 10.1023/B:APBI.0000017864.06525.eb</ref>.
 
<br>
 
<span style="background-color: initial; font-size: 19.92px;">Differential Diagnosis<ref name="Bhidiyasiri" /></span>  


== Differential Diagnosis<span style="background-color: initial; font-size: 19.92px;"><ref name="Bhidiyasiri">Bhidayasiri, R. Differential diagnosis of common tremor syndromes. Postgrad Med J 2005;81:756-762. DOI: 10.1136/pgmj.2005.032979</ref></span> ==
*Resting tremor  
*Resting tremor  
*Postural tremor  
*Postural tremor  
Line 67: Line 46:
*Isometric tremor  
*Isometric tremor  
*Task-specific tremor
*Task-specific tremor
== Key Evidence  ==
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== Resources <br>  ==
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== Case Studies  ==
<br>
== References  ==
== References  ==
References will automatically be added here, see [[Adding References|adding references tutorial]].


<references />  
<references />  


[[Category:Neurology]] [[Category:Queen's_University_Neuromotor_Function_Project]]
[[Category:Neurology]]  
[[Category:Queen's_University_Neuromotor_Function_Project]]
[[Category:Conditions]]
[[Category:Neurological - Conditions]]

Latest revision as of 11:16, 17 February 2023

Original Editor - Jonathan De Leyer, Brooke Eveleigh, Kyrie Hicks, Peter Kmiecik, Julie Walden as part of the Queen's University Neuromotor Function Project Top Contributors - Kyrie Hicks, Brooke Eveleigh, Kim Jackson, Jonathan de Leyer, Julie Walden, Lucinda hampton, 127.0.0.1, Peter Kmiecik, Aminat Abolade, Evan Thomas and WikiSysop

Introduction[edit | edit source]

Spirals drawn by a patient with unilateral ET

Essential tremor (ET) is classified as a neurological disorder. It usually presents as a bilateral postural (6 to 12 Hz) tremor of the hands, followed by a kinetic and resting component. The upper limbs are often symmetrically involved, but with ET progression, the head and voice (less often legs, jaw, face, and trunk) might be involved. Despite the fact that is is benign in respect to its effect on life expectancy, it often causes embarrassment and, in a tiny percentage of patients, also serious disability. Symptoms are typically progressive and potentially disabling, for example it may force patients to change jobs or seek early retirement. The key is first to educate the patient on the disorder and its treatment.[1][2]

Etiology[edit | edit source]

The etiology of essential tremor is not known. About 50% of the cases of ET appear to result from a genetic mutation (no specific gene has been identified), and is is referred to as familial tremor. The lack of consistency of age of onset, the presence of sporadic cases, and incomplete concordance of essential tremor among monozygotic twins leads to the view that environmental factors play a role.

The Movement Disorders Society diagnostic criteria include:

  1. Tremor is bilateral, symmetrical, and postural
  2. The tremor involves the forearms and hand
  3. Is persistent and visible
  4. It may be associated with isolated head tremor[2]

Epidemiology[edit | edit source]

ET is considered to be one of the most, if not the most, common adult movement disorders[3]. The worldwide estimated prevalence is up to 5% of the population. Family history can be found in near 50% of cases. The incidence of essential tremor increases with age, however it often affects young individuals, mainly when it is familial.[2]

Diagnosis[edit | edit source]

There are no special tests for diagnosing essential tremor. The doctor will usually make a diagnosis after a detailed neurologic examination to identify specific features of the tremor.

The core criteria require either a bilateral action tremor of the hands and forearms and the absence of other neurologic signs. Other information strongly suggestive of essential tremor includes long duration (more than 3 years) of the tremor, a positive family history of essential tremor, and beneficial response to stress reduction.[2]

Clinical Presentation[edit | edit source]

Essential tremor primarily presents as a kinetic tremor of the upper extremities, meaning it appears when we move throughout our various daily activities[4][5]. The tremor typically oscillates between 4 and 12 Hz, with the frequency of the tremor being inversely proportional to one’s age [6][7]. The tremor may also present as intention tremor, increasing in magnitude and frequency as the patient voluntarily moves their arm or hand closer to specific objects or points[4].

Although primarily located in the arms, essential tremor may gradually spread in a somatotrophic fashion to other parts of the body such as the head or voice, or less commonly the lower extremities[5]. Patients experiencing more severe or farther progressed essential tremor may present with additional postural tremor or may be disabled in their ability to perform activities of daily living (ADLs) such as eating and dressing[6][4]. Essential tremor presents with a larger set of additional characteristics than initially thought[4]. These include motor features such as signs of cerebellar dysfunction and tremor at rest, as well as non-motor features such as cognitive deficits and personality changes[4][6].

Medical Management[edit | edit source]

Less impaired patients may choose no treatment. Some patients that are not functionally impaired desire treatment because their tremor causes social embarrassment. Options for patients with significant functional impairment include non-medical, medical, or interventional therapy.

  1. Non medical therapy. For some patients, tremors can be reduced by weighting the limb, typically by applying wrist weights (this dampening the tremor enough to provide some relief or improve functioning for a few patients). Since anxiety and stress make the tremor worse, non-medical relaxation techniques and biofeedback may help some patients. Medications known to make tremors worse should be eliminated or reduced if possible. People with ED may possibly benefit from avoiding dietary stimulants, for example caffeine. Also commercially available technologies eg weighted utensils, may be helpful for some patients.[2]
  2. Pharmacological treatment for ET has shown some promising results. Propranolol and primidone are the most commonly used drugs. They have around a 50 - 70% effectiveness in patients. However, there are some side effects such as dizziness, nausea, fast or slow heart beat, and drowsiness among others[8]. Topiramate is an alternative medication used for ET and is often used when the previous two are ineffective. It is effective in about 22-37% of patients. A recent systematic review by Bruno et al 2017 found that while effective, more studies are still needed to determine its efficacy and safety[9].
  3. Two main types of surgical techniques are used for essential tremor, deep brain stimulation and thalamotomy. Deep brain stimulation (DBS) was originally used for treating Parkinson’s Disease but has been us to treat ET as well. It involves implanting electrodes in the thalamus in the ventral intermediate nucleus. These are then connected to a pulse generator typically located behind the clavicle. When it is turned on it stimulates the thalamus reducing the tremor. It can be turned on and off at the patients discretion. A systematic review in 2010 found that DBS significantly improved outcomes in patients with ET. Moreover, any mild adverse effects they produced were reduced by modulating the pulse of the deep brain stimulation[10].
    Thalamotomy involves lesioning the portions of the thalamus that cause the tremors. Different types include radiofrequency thalamotomy, laser induced thermal therapy, magnetic resonance guided focused ultrasound, focused thermolesions and gamma knife thalamotomy. They essentially do the same thing but due to different procedures some are associated with higher risks[8].

Physical Therapy Management[edit | edit source]

Physical therapy treatment for ET primarily focuses on resistance training. Typically, this is done on the upper extremity to improve strength and coordination, and to reduce tremor severity. Six weeks of resistance training using bicep curls, wrist flexion and extension has been shown to improve these outcome measures[11][12]. Even performing isometric loads on the index finger reduces pointing variability for patients with ET[13]. In addition to resistance training, behavioral relaxation therapy has been shown to decrease the tremor severity. Behavioral relaxation involves putting the patient into a relaxed position using a ten-step progression. This is done because stress has been shown to increase the severity of tremors[14].

Differential Diagnosis[15][edit | edit source]

  • Resting tremor
  • Postural tremor
  • Kinetic tremor
  • Isometric tremor
  • Task-specific tremor

References[edit | edit source]

  1. ↑ Abboud, H., Ahmed, A., Fernandez, HH. Essential tremor: choosing the right management plan for your patient. Cleve Clin J Med 2011;78(12):821-8.
  2. ↑ 2.0 2.1 2.2 2.3 2.4 Agarwal S, Biagioni MC. Essential tremor. InStatPearls [Internet] 2021 Jul 12. StatPearls Publishing. Available:https://www.ncbi.nlm.nih.gov/books/NBK499986/ (accessed 15.9.2022)
  3. ↑ Louis ED, Ford B, Lee H, Andrews H. Does a screening questionnaire for essential tremor agree with the physician’s examination? Neurology 1998;50:1351–1357 DOI: http://dx.doi.org/10.1212/WNL.50.5.1351
  4. ↑ 4.0 4.1 4.2 4.3 4.4 Louis, E. D. (2006). Essential tremor. Clinics in Geriatric Medicine, 22(4), 843-857. doi:10.1016/j.cger.2006.06.012
  5. ↑ 5.0 5.1 Louis, E. D. Essential tremor. Lancet Neurology, 2005;4(2),100-110. doi:10.1016/S1474-4422(05)00991-9
  6. ↑ 6.0 6.1 6.2 Brennan, K. C., Jurewicz, E. C., Ford, B., Pullman, S. L., & Louis, E. D. Is essential tremor predominantly a kinetic or a postural tremor? A clinical and electrophysiological study. Movement Disorders, 2002;17(2):313-316. doi:10.1002/mds.10003
  7. ↑ Deuschl, G., Bain, P., & Brin, M. Consensus statement of the movement disorder society on tremor. Movement Disorders, 1998;13(S3):2-23. doi:10.1002/mds.870131303
  8. ↑ 8.0 8.1 Witjas, T., Carron, R., Boutin, E., Eusebio, A., Auzulay, J.P., Régis, J. Essential tremor: Update of therapeutic strategies (medical treatment and gamma knife thalamotomy. Revue Neurologique 2016;172(8-9):408-415. DOI: 10.1016/j.neurol.2016.07.014
  9. ↑ Bruno, E., Nicoletti, A., Quattrocchi, G., Allegra, R., Fillippini, G., Colsimo, C., Zappia, M. Topiramate for essential tremor. Cochrane Reviews 2017. DOI: 10.1002/14651858.CD009683.pub2
  10. ↑ Della Flora, E., Perera, C.L., Cameron, A.L., Maddern, G.J. Deep brain stimulation for essential tremor: A systematic review. Movement Disorders 2010;25(11):1550-1559. PMID: 20623768
  11. ↑ Kavanagh, J.J., Wedderburn-Bisshop, J., Keogh, J.W.L. Resistance training reduces force tremor and improves manual dexterity in older individuals with essential tremor. Journal of Motor Behavior 2016;48(1):20-30. DOI: 10.1080/00222895.2015.1028583
  12. ↑ Sequiera, G., Keogh, J.W., Kavanagh, J.J. Resistance training can improve fine manual dexterity in essential tremor patients: A preliminary study. Archives of Physical Medicine and Rehabilitation 2012;93(8):1466-1468. DOI: 10.1016/j.apmr.2012.02.003
  13. ↑ Bilodeau, M., Keen, D.A., Sweeney, P.J., Shields, R.W., & Enoka, R.M. Muscle & Nerve 2000;23(5):771-778. DOI: 10.1002/(SICI)1097-4598(200005)23:5&lt;771::AID-MUS15&gt;3.0.CO;2-9
  14. ↑ Lundervold, D.A., Poppen, R. Biobehvioural intervention for older adults with essential tremor. Applied Psychophysiology and Biofeedback 2004;29(1):63-73. DOI: 10.1023/B:APBI.0000017864.06525.eb
  15. ↑ Bhidayasiri, R. Differential diagnosis of common tremor syndromes. Postgrad Med J 2005;81:756-762. DOI: 10.1136/pgmj.2005.032979
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