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'''For patient information, click [[Essential tremor (patient information)|here]]'''
==Overview==
 
Tremor is a neurological disorder characterized by involuntary and rhythmic movements of [https://www.bbc.co.uk/bitesize/guides/zct2hv4/revision/2#:~:text=The%20muscle%20that%20is%20contracting,lengthening%20is%20called%20the%20antagonist.&text=One%20way%20to%20remember%20which,is%20doing%20all%20the%20work. agonist] and [https://www.bbc.co.uk/bitesize/guides/zpkr82p/revision/4#:~:text=In%20an%20antagonistic%20muscle%20pair,lengthening%20is%20called%20the%20antagonist. antagonist muscles] it affects numerous body parts(1), including the hands, vocal cords, legs, arms, head, face, and tongue<ref name="pmid29193359">{{cite journal| author=Bhatia KP, Bain P, Bajaj N, Elble RJ, Hallett M, Louis ED | display-authors=etal| title=Consensus Statement on the classification of tremors. from the task force on tremors of the International Parkinson and Movement Disorder Society. | journal=Mov Disord | year= 2018 | volume= 33 | issue= 1 | pages= 75-87 | pmid=29193359 | doi=10.1002/mds.27121 | pmc=6530552 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=29193359  }} </ref> . It is not a life-threatening disease but has a major influence on a person's everyday activities. Tremors are classified into two types: '''rest tremors'<nowiki/>'', '''''which occur while a person is at rest and '''activity tremors''', which occur while moving. '''Action tremors''' are classified into numerous categories, including postural, kinetic, purposeful, task-specific, and [https://link.springer.com/chapter/10.1007/978-3-031-26128-2_8 isometric tremors]<ref name="pmid22371630">{{cite journal| author=Grinnon ST, Miller K, Marler JR, Lu Y, Stout A, Odenkirchen J | display-authors=etal| title=National Institute of Neurological Disorders and Stroke Common Data Element Project - approach and methods. | journal=Clin Trials | year= 2012 | volume= 9 | issue= 3 | pages= 322-9 | pmid=22371630 | doi=10.1177/1740774512438980 | pmc=3513359 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=22371630  }} </ref>. In 1874 Burresi initially used the term Essential tremor (ET), or family tremor, to describe a condition marked by a “bilateral upper extremity action tremor.” Lasting for at least 3 years without any other neurological signs such as [[Parkinsonism (patient information)|Parkinsonism]]. An essential tremor with neurological signs is referred as an “essential tremor plus” is one of the most prevalent hyper kinetic tremors in adults. Historical Perspective <ref name="pmid18779514">{{cite journal| author=Louis ED, Broussolle E, Goetz CG, Krack P, Kaufmann P, Mazzoni P| title=Historical underpinnings of the term essential tremor in the late 19th century. | journal=Neurology | year= 2008 | volume= 71 | issue= 11 | pages= 856-9 | pmid=18779514 | doi=10.1212/01.wnl.0000325564.38165.d1 | pmc=3461999 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=18779514  }} </ref>.
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  Caption        = |
  DiseasesDB    = |
  ICD10          = {{ICD10|G|25|0|g|20}} |
  ICD9          = {{ICD9|333.1}} |
  ICDO          = |
  OMIM          = 190300 |
  OMIM_mult      = {{OMIM2|602134}} |  
  MedlinePlus    = 000762 |
  MeshID        = D020329 |
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{{SI}}
{{CMG}}{{AE}}{{Rina Ghorpade}}


==Overview==
'''Essential tremor''' is a [[neurological disorder]] characterized by shaking of [[hand]]s (and sometimes other parts of the body including the [[head (anatomy)|head]]), evoked by intentional movements. The exact incidence is unknown, but it is presumed to be the most common type of [[tremor]] and also the most commonly observed movement disorder. Essential tremor was also previously known as "benign essential tremor", but the adjective "benign" has been removed in recognition of the sometimes disabling nature of the disorder.
==Historic Perspective==
==Historic Perspective==


The term ''essentieller Tremor (''essential tremor) was first coined by Raymond (France, 1892)<ref name="pmid18779514">{{cite journal| author=Louis ED, Broussolle E, Goetz CG, Krack P, Kaufmann P, Mazzoni P| title=Historical underpinnings of the term essential tremor in the late 19th century. | journal=Neurology | year= 2008 | volume= 71 | issue= 11 | pages= 856-9 | pmid=18779514 | doi=10.1212/01.wnl.0000325564.38165.d1 | pmc=3461999 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=18779514  }}</ref>. This term gained widespread use among neurologists during the second half of the 20th century to describe the familial cases of tremors.
The term ''essentieller Tremor (''essential tremor) was first coined by Raymond (France, 1892).This term gained widespread use among neurologists during the second half of the 20th century to describe the familial cases of tremors.<ref name="pmid18779514">{{cite journal| author=Louis ED, Broussolle E, Goetz CG, Krack P, Kaufmann P, Mazzoni P| title=Historical underpinnings of the term essential tremor in the late 19th century. | journal=Neurology | year= 2008 | volume= 71 | issue= 11 | pages= 856-9 | pmid=18779514 | doi=10.1212/01.wnl.0000325564.38165.d1 | pmc=3461999 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=18779514  }}</ref>.  


==Classification==
==Classification==
Line 29: Line 12:
==Pathophysiology==
==Pathophysiology==


The [[pathogenesis]] of essential tremor (ET) is not fully explained. There is a strong [[genetic]] component. It has an [[autosomal dominant]] pattern of [[inheritance]], and almost 80% of patients have a family history of [[tremors]]<ref name="pmid18043006">{{cite journal| author=Louis ED, Dogu O| title=Does age of onset in essential tremor have a bimodal distribution? Data from a tertiary referral setting and a population-based study. | journal=Neuroepidemiology | year= 2007 | volume= 29 | issue= 3-4 | pages= 208-12 | pmid=18043006 | doi=10.1159/000111584 | pmc=2824583 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=18043006 }} </ref>.
The cause of tremor in ET is still unknown; several hypotheses have been made to understand the pathophysiology of the disease including the neurodegenerative hypothesis, central oscillatory network hypothesis, and GABAergic hypothesis. the neurodegenerative hypothesis is a matter of debate due to contradicting outcomes in the studies like degeneration or remodeling of [[Purkinje cell|Purkinje cells]] in ET other studies do not support the findings many studies report degeneration of the cerebellum but other studies do not support the finding, central oscillatory network hypothesis suggests that interconnected signals among brain region including [[cerebellum]], [[thalamus]], [[cortex]], and [[inferior olive]] collaborate to generate tremors. The GABAergic hypothesis suggests that the irregular activity within a brain region cerebello-thalamo-cortical occurs due to disturbances in the transmission of the neurotransmitter GABA or alterations in a specific type of receptor for GABA known as GABA-A receptors<ref name="pmid34944457">{{cite journal| author=Kosmowska B, Wardas J| title=The Pathophysiology and Treatment of Essential Tremor: The Role of Adenosine and Dopamine Receptors in Animal Models. | journal=Biomolecules | year= 2021 | volume= 11 | issue= 12 | pages= | pmid=34944457 | doi=10.3390/biom11121813 | pmc=8698799 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=34944457 }} </ref>.
The [[neuropathology]] of ET remains highly debatable, although some believe that it is localized to [[brainstem]] and [[cerebellum]], it is a controversial theory.


==Cause==
==Cause==
Half of the cases are due to gene mutation and transmitted dominantly. There are two main loci: [[ETM1]] and [[ETM2]].<ref>{{cite journal |author=Kovach M, Ruiz J, Kimonis K et al |title=Genetic heterogeneity in autosomal dominant essential tremor |journal=Genet Med |volume=3 |issue=3 |pages=197-9 |year=2001  |pmid=11388761}}</ref> The rest are [[idiopathic]]. No identifiable and consistent structural abnormality has yet been demonstrated to exist in the [[nervous system]] of every person with ET.
The cause of the diseases is not clear but various studies suggest that genes play an important role in developing diseases (13), environmental factors are also considered as disease-causing factors.


A French kindred study found that the Ser9Gly variant of the [[dopamine receptor]] D3 (DRD3) was strongly associated with ET in 23 out of 30 families studied.<ref>{{cite journal | title=A functional variant of the dopamine D3 receptor is associated with risk and age-at-onset of essential tremor | journal=Proc Natl Acad Sci U S A | year=2006 | volume=103 | issue=28 | pages=10753&ndash;8 | author=Jeanneteau F, Funalot B, Jankovic J, ''et al.'' | id=PMID 16809426 }}</ref>
'''Genetics:'''


==Clinical Features==
ET is a hereditary disease and about 30-70% of individuals suffer from owing to past family history, the chances of ET rise 4.7 times if the first-degree relative has the disease many types of research have been done to identify the genetic marker for the diseases  .but the responsible gene is not clear yet. One study linked ET susceptibility to the DRD3 gene in Icelandic families. At the same time, another found the HS1BP3 gene in an American family<ref name="pmid15699368">{{cite journal| author=Higgins JJ, Lombardi RQ, Pucilowska J, Jankovic J, Tan EK, Rooney JP| title=A variant in the HS1-BP3 gene is associated with familial essential tremor. | journal=Neurology | year= 2005 | volume= 64 | issue= 3 | pages= 417-21 | pmid=15699368 | doi=10.1212/01.WNL.0000153481.30222.38 | pmc=1201396 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=15699368  }} </ref>. ETM3 on chromosome 6p23 was identified as a locus . GWAS highlighted potential ET susceptibility genes like LINGO1 and SLC1A2 <ref name="pmid22764253">{{cite journal| author=Thier S, Lorenz D, Nothnagel M, Poremba C, Papengut F, Appenzeller S | display-authors=etal| title=Polymorphisms in the glial glutamate transporter SLC1A2 are associated with essential tremor. | journal=Neurology | year= 2012 | volume= 79 | issue= 3 | pages= 243-8 | pmid=22764253 | doi=10.1212/WNL.0b013e31825fdeed | pmc=3398434 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=22764253  }} </ref>. Exome sequencing revealed a pathogenic FUS variant in a French-Canadian family. Further research found HTRA2 in Turkish and pathogenic variants in the TENM4 gene in a Spanish population. These findings highlight the complex genetic basis of ET <ref name="pmid25422467">{{cite journal| author=Unal Gulsuner H, Gulsuner S, Mercan FN, Onat OE, Walsh T, Shahin H | display-authors=etal| title=Mitochondrial serine protease HTRA2 p.G399S in a kindred with essential tremor and Parkinson disease. | journal=Proc Natl Acad Sci U S A | year= 2014 | volume= 111 | issue= 51 | pages= 18285-90 | pmid=25422467 | doi=10.1073/pnas.1419581111 | pmc=4280582 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=25422467  }} </ref>.


'''Acquired factors:'''


 
Neurological illnesses are strongly influenced by lifestyle and environmental factors. Recent study reveals that ethanol, which was formerly considered to ease tremors, may instead act as a cerebellar toxin, inadequate sleep has been linked to a higher incidence of tremors and Lead exposure has been connected with essential tremors (ET)<ref name="pmid14594619">{{cite journal| author=Louis ED, Jurewicz EC, Applegate L, Factor-Litvak P, Parides M, Andrews L | display-authors=etal| title=Association between essential tremor and blood lead concentration. | journal=Environ Health Perspect | year= 2003 | volume= 111 | issue= 14 | pages= 1707-11 | pmid=14594619 | doi=10.1289/ehp.6404 | pmc=1241711 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=14594619  }} </ref>
==Differential Diagnosis==


==Epidemilogy==
==Epidemilogy==


ET is a genetic disease and it is more common in males than females initially its symptoms are mild but it worsens with age (26). ET has a worldwide incidence of 0.9%, which can rise to 4.0% and 22% in patients aged greater than 40 and 90 years respectively .


==Risk Factors==
==Risk Factors==


 
Over time mild ET can progress and age-related factors can act as a bridge in the progression of the diseases resulting in the emergence of neurological symptoms.Late onset of the disease is associated with rapid progression, dementia, Parkinson's diseases, and death, caffeine, medication, low blood sugar, fatigue strong emotion, stress can trigger tremor related to ET.
==Screening==
 
==Natural History, Complications, and Prognosis==
 
 
 


==Diagnosis==
==Diagnosis==
Usually the diagnosis is established on clinical grounds.  
Initially, ET was considered a purely motor disease. Still, letter non-motor features are also recognized<ref name="pmid33503062">{{cite journal| author=Shalash AS, Hamid E, Elrassas H, Bahbah EI, Mansour AH, Mohamed H | display-authors=etal| title=Non-motor symptoms in essential tremor, akinetic rigid and tremor-dominant subtypes of Parkinson's disease. | journal=PLoS One | year= 2021 | volume= 16 | issue= 1 | pages= e0245918 | pmid=33503062 | doi=10.1371/journal.pone.0245918 | pmc=7840014 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=33503062  }} </ref>.ET symptoms include fatigue, personality changes, olfactory dysfunction, hearing impairment, and sleep disturbances. anxiety<ref name="pmid38708124">{{cite journal| author=Gerbasi ME, Elble RJ, Jones E, Gillespie A, Jarvis J, Chertavian E | display-authors=etal| title=Associations Among Tremor Amplitude, Activities of Daily Living, and Quality of Life in Patients with Essential Tremor. | journal=Tremor Other Hyperkinet Mov (N Y) | year= 2024 | volume= 14 | issue=  | pages= 22 | pmid=38708124 | doi=10.5334/tohm.877 | pmc=11067966 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=38708124  }} </ref>.Tremors observed in ET patients with the frequency of  4-8 Hz(1)<ref name="pmid38247412">{{cite journal| author=Kim YW, Kim S, Jin MJ, Im CH, Lee SH| title=The Importance of Low-frequency Alpha (8-10 Hz) Waves and Default Mode Network in Behavioral Inhibition. | journal=Clin Psychopharmacol Neurosci | year= 2024 | volume= 22 | issue= 1 | pages= 53-66 | pmid=38247412 | doi=10.9758/cpn.22.1035 | pmc=10811390 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=38247412  }} </ref>, depression is considered as primary symptom and associated with disability in  ET patients, cognitive impairment is also reported in these patients and it is progressive from mild to dementia,  the affected cognitive domain is an executive function and memory. These patients feel difficulty in writing, drinking, eating, personal hygiene, and other routine task. In some situations, ET can constantly shake the hands or tongue, making it difficult to thread a needle, and using a ruler becomes difficult<ref name="pmid38708124">{{cite journal| author=Gerbasi ME, Elble RJ, Jones E, Gillespie A, Jarvis J, Chertavian E | display-authors=etal| title=Associations Among Tremor Amplitude, Activities of Daily Living, and Quality of Life in Patients with Essential Tremor. | journal=Tremor Other Hyperkinet Mov (N Y) | year= 2024 | volume= 14 | issue= | pages= 22 | pmid=38708124 | doi=10.5334/tohm.877 | pmc=11067966 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=38708124  }} </ref>. As it is suggested that it is a hereditary disease it is initially diagnosed by the medical history, family history, and physical examination which help to evaluate the tremor of the head, arm, voice, and leg. In 2018 Moment Disorder Society (MDS) classified ET into two categories including ''' ET''' and ''' ET plus''' through electromyography and accelerometry artificial intelligence to interpret accelerometry data and distinguish between ET and Parkinson's disease. It has been applied to the analysis of video recordings of tremors.
Tremors can start at any age, from [[childbirth|birth]] through advanced ages (senile tremor). Any voluntary muscle in the body may be affected, though it's most commonly seen in the [[hands]] and [[arm]]s and slightly less commonly in the [[neck]] (causing the patient's head to shake), [[eyelid]]s, [[larynx]], [[tongue]], trunk, and legs. A resting tremor of the hands is sometimes present.
 
ET does sometimes occur in combination with other neurological disorders such as [[dystonia]] and [[benign fasciculation syndrome]]. However, there is no clear evidence that having ET predisposes a person to one of these disorders.
 
==Symptoms==
Essential tremor (ET) generally presents as a rhythmic tremor (4-12[[Hertz|Hz]]) that is present only when the affected [[muscle]] is exerting effort (i.e., it is not present at rest). Any sort of physical or mental [[stress (medicine)|stress]] will tend to make the tremor worse, often creating the false impression that the tremor is of [[psychosomatic]] origin. It is typical for the tremor to worsen in "performance" situations, such as when making out a check at a checkout stand. ET-related tremors do not occur during sleep, but patients sometimes complain of an especially coarse tremor upon awakening that becomes noticeably less coarse within the first few minutes of wakefulness. Tremor intensity can otherwise worsen in response to fatigue, strong emotions, low blood sugar, cold, caffeine, lithium salts, some antidepressants or other factors.
 
In disabling cases, ET can interfere with a person's ability to perform tasks of daily living, including feeding, dressing, and activities of personal hygiene.
 
ET is usually painless, although in some cases tremor of the head or [[neck]] causes pain, and writing can become painful quickly for a person with hand tremors who grips a pen tightly in a struggle to maintain control over penmanship.
 
Sometimes people with ET develop a raspy speaking voice while their ET symptoms worsen over time. When this [[dysphonia]] occurs, it is true even in cases where the person's tremor symptoms were first noticeable during early childhood and, so, is unlikely to be related to commonplace reductions in quality that can gradually affect the speaking voices of some elderly people.
 
People with ET often report a progressive decline in their sense of balance and their fine motor skills.
 
ET is clearly progressive in most cases (sometimes rapidly, sometimes very slowly), and can be disabling, but significant disability is rare.
 
==Treatment==
Drug treatment may include [[tranquilizer]]s, [[beta-blocker]]s, and [[antiepileptic]] drugs. [[Surgery|Surgical]] treatments (which are generally reserved for the most severe cases) include [[botulism]] toxin injections into the affected muscles, [[thalamotomy]], [[pallidotomy]], and [[deep brain stimulation]] &ndash; the insertion of a [[brain pacemaker]].
 
The two medications that are prescribed most commonly for control of ET symptoms are the anticonvulsant [[Primidone]] (Mysoline) and the beta-blocker [[propranolol]] (Inderal).
 
Minor cases of ET can be treated with physical therapy and development of the muscles in the sections of the body that are severe in their shaking.
 
Other potential sources of tremor (excessive [[caffeine]] consumption, [[recreational drug use]], medications, [[hyperthyroidism]]) should be excluded if possible
 
==Support groups==
The International Essential Tremor Foundation (IETF) provides information, services, and support to individuals and families affected by essential tremor (ET). The organization encourages and promotes research in an effort to determine the causes, treatment, and ultimately the cure for ET. The IETF is a worldwide organization dedicated to meeting the needs of those whose daily lives are challenged by ET. IETF, an international non-profit 501(c)(3) organization that derives its support entirely from its membership and the general public, was founded in 1988 and is guided by a board of directors and a medical advisory council. The organization's membership consists of patients, physicians, educators, parents, relatives and volunteers who provide education, community services, and funding to help support tremor research.
 
The National Tremor Foundation (NTF), founded in 1992, is a British friendly organization based in Essex, England, an affiliate of the International Tremor Foundation, which was founded in 1988.  The organization's primary work is the production of a quarterly informational newsletter.  The NTF also maintains a list of ITF medical advisors and facilitates the formation of self-help groups.  NTF was granted charitable status in 1994.
 
==Help with Technology==
Tunic Software has released software to help people with essential tremor, [[Parkinson's Disease]], and other causes of hand tremor control their [[computer mouse]]. Called 'MouseCage', the software automatically smooths mouse cursor motion to reduce the effects of unsteady or shaky hands.[http://www.filedudes.com/MouseCage-download-22071.html - anti-tremor mouse software]
 
IBM created a peripheral device that filters out tremoring movements of the hand. The hardware adapter, termed AMA, is connected between the computer and the input device. It is switched on or off and adjusted for tremor severity right on the device.  
 
IBM also offers a free smoothing mouse driver for windows 2000 and XP which uses the same technology that helps steady the image in a hand held camcorder.  See http://www.alphaworks.ibm.com/tech/mousesmoothing
 
Another option is http://www.steadymouse.com/about/


Other tools have also been adapted for people with tremors; for example, eating utensils which are weighted to help damp out tremor.
== Treatment ==
Patients might seek medical help only when symptoms interfere with daily activities. To overcome the diseases, medication and surgical treatments are provided. Combined therapy can sometimes show better clinical outcomes and thus surgical intervention is considered in severe cases and disabling despite treatment<ref name="pmid37738526">{{cite journal| author=Antonazzo IC, Rozza D, Conti S, Fornari C, Cortesi PA, Eteve-Pitsaer C | display-authors=etal| title=Treatment patterns in essential tremor: Real-world evidence from the United Kingdom and France primary care database. | journal=Eur J Neurol | year= 2024 | volume= 31 | issue= 1 | pages= e16064 | pmid=37738526 | doi=10.1111/ene.16064 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=37738526  }} </ref>. The primary therapy for ET is Propranolol and primidone <ref name="pmid31948986">{{cite journal| author=Zhang M, Li W, Hu L, Chen L, Yang L, Zhang T | display-authors=etal| title=Oral propranolol for treatment of the subgroups of essential tremor: a systematic review and meta-analysis protocol. | journal=BMJ Open | year= 2020 | volume= 10 | issue= 1 | pages= e032096 | pmid=31948986 | doi=10.1136/bmjopen-2019-032096 | pmc=7044890 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=31948986  }} </ref> and other medications are also used for the treatment including gabapentin, alprazolam, and topiramate. The second option to overcome the disease is surgery which includes deep brain stimulation (DBS), radio-frequency thalamotomy, and MRI-guided focused ultrasound thalamotomy. Some other Therapies are also introduced nowadays that help to overcome the disease burden including TAPS (FDA approved)<ref name="pmid36222768">{{cite journal| author=Wagle Shukla A| title=Diagnosis and Treatment of Essential Tremor, Vibratory therapy (under trials), T-type Calcium Channel modulator (Undergoing Phase 2 trials), GABA-A Receptor modulator(Undergoing Phase 2 studies), Chemodenervation(Not FDA approved for tremor; undergoing Phase 2 study for tremor)<ref name="pmid36222768">{{cite journal| author=Wagle Shukla A| title=Diagnosis and Treatment of Essential Tremor. | journal=Continuum (Minneap Minn) | year= 2022 | volume= 28 | issue= 5 | pages= 1333-1349 | pmid=36222768 | doi=10.1212/CON.0000000000001181 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=36222768  }} </ref>.


==References==
==References==

Latest revision as of 06:09, 15 June 2024

Overview

Tremor is a neurological disorder characterized by involuntary and rhythmic movements of agonist and antagonist muscles it affects numerous body parts(1), including the hands, vocal cords, legs, arms, head, face, and tongue[1] . It is not a life-threatening disease but has a major influence on a person's everyday activities. Tremors are classified into two types: rest tremors', which occur while a person is at rest and activity tremors, which occur while moving. Action tremors are classified into numerous categories, including postural, kinetic, purposeful, task-specific, and isometric tremors[2]. In 1874 Burresi initially used the term Essential tremor (ET), or family tremor, to describe a condition marked by a “bilateral upper extremity action tremor.” Lasting for at least 3 years without any other neurological signs such as Parkinsonism. An essential tremor with neurological signs is referred as an “essential tremor plus” is one of the most prevalent hyper kinetic tremors in adults. Historical Perspective [3].

Historic Perspective

The term essentieller Tremor (essential tremor) was first coined by Raymond (France, 1892).This term gained widespread use among neurologists during the second half of the 20th century to describe the familial cases of tremors.[3].

Classification

There is no system to classify essential tremor.

Pathophysiology

The cause of tremor in ET is still unknown; several hypotheses have been made to understand the pathophysiology of the disease including the neurodegenerative hypothesis, central oscillatory network hypothesis, and GABAergic hypothesis. the neurodegenerative hypothesis is a matter of debate due to contradicting outcomes in the studies like degeneration or remodeling of Purkinje cells in ET other studies do not support the findings many studies report degeneration of the cerebellum but other studies do not support the finding, central oscillatory network hypothesis suggests that interconnected signals among brain region including cerebellum, thalamus, cortex, and inferior olive collaborate to generate tremors. The GABAergic hypothesis suggests that the irregular activity within a brain region cerebello-thalamo-cortical occurs due to disturbances in the transmission of the neurotransmitter GABA or alterations in a specific type of receptor for GABA known as GABA-A receptors[4].

Cause

The cause of the diseases is not clear but various studies suggest that genes play an important role in developing diseases (13), environmental factors are also considered as disease-causing factors.

Genetics:

ET is a hereditary disease and about 30-70% of individuals suffer from owing to past family history, the chances of ET rise 4.7 times if the first-degree relative has the disease many types of research have been done to identify the genetic marker for the diseases  .but the responsible gene is not clear yet. One study linked ET susceptibility to the DRD3 gene in Icelandic families. At the same time, another found the HS1BP3 gene in an American family[5]. ETM3 on chromosome 6p23 was identified as a locus . GWAS highlighted potential ET susceptibility genes like LINGO1 and SLC1A2 [6]. Exome sequencing revealed a pathogenic FUS variant in a French-Canadian family. Further research found HTRA2 in Turkish and pathogenic variants in the TENM4 gene in a Spanish population. These findings highlight the complex genetic basis of ET [7].

Acquired factors:

Neurological illnesses are strongly influenced by lifestyle and environmental factors. Recent study reveals that ethanol, which was formerly considered to ease tremors, may instead act as a cerebellar toxin, inadequate sleep has been linked to a higher incidence of tremors and Lead exposure has been connected with essential tremors (ET)[8]

Epidemilogy

ET is a genetic disease and it is more common in males than females initially its symptoms are mild but it worsens with age (26). ET has a worldwide incidence of 0.9%, which can rise to 4.0% and 22% in patients aged greater than 40 and 90 years respectively .

Risk Factors

Over time mild ET can progress and age-related factors can act as a bridge in the progression of the diseases resulting in the emergence of neurological symptoms.Late onset of the disease is associated with rapid progression, dementia, Parkinson's diseases, and death, caffeine, medication, low blood sugar, fatigue strong emotion, stress can trigger tremor related to ET.

Diagnosis

Initially, ET was considered a purely motor disease. Still, letter non-motor features are also recognized[9].ET symptoms include fatigue, personality changes, olfactory dysfunction, hearing impairment, and sleep disturbances. anxiety[10].Tremors observed in ET patients with the frequency of  4-8 Hz(1)[11], depression is considered as primary symptom and associated with disability in  ET patients, cognitive impairment is also reported in these patients and it is progressive from mild to dementia,  the affected cognitive domain is an executive function and memory. These patients feel difficulty in writing, drinking, eating, personal hygiene, and other routine task. In some situations, ET can constantly shake the hands or tongue, making it difficult to thread a needle, and using a ruler becomes difficult[10]. As it is suggested that it is a hereditary disease it is initially diagnosed by the medical history, family history, and physical examination which help to evaluate the tremor of the head, arm, voice, and leg. In 2018 Moment Disorder Society (MDS) classified ET into two categories including ET and ET plus through electromyography and accelerometry artificial intelligence to interpret accelerometry data and distinguish between ET and Parkinson's disease. It has been applied to the analysis of video recordings of tremors.

Treatment

Patients might seek medical help only when symptoms interfere with daily activities. To overcome the diseases, medication and surgical treatments are provided. Combined therapy can sometimes show better clinical outcomes and thus surgical intervention is considered in severe cases and disabling despite treatment[12]. The primary therapy for ET is Propranolol and primidone [13] and other medications are also used for the treatment including gabapentin, alprazolam, and topiramate. The second option to overcome the disease is surgery which includes deep brain stimulation (DBS), radio-frequency thalamotomy, and MRI-guided focused ultrasound thalamotomy. Some other Therapies are also introduced nowadays that help to overcome the disease burden including TAPS (FDA approved).

References

  1. ↑ Bhatia KP, Bain P, Bajaj N, Elble RJ, Hallett M, Louis ED; et al. (2018). "Consensus Statement on the classification of tremors. from the task force on tremors of the International Parkinson and Movement Disorder Society". Mov Disord. 33 (1): 75–87. doi:10.1002/mds.27121. PMC 6530552 Check |pmc= value (help). PMID 29193359.
  2. ↑ Grinnon ST, Miller K, Marler JR, Lu Y, Stout A, Odenkirchen J; et al. (2012). "National Institute of Neurological Disorders and Stroke Common Data Element Project - approach and methods". Clin Trials. 9 (3): 322–9. doi:10.1177/1740774512438980. PMC 3513359. PMID 22371630.
  3. ↑ 3.0 3.1 Louis ED, Broussolle E, Goetz CG, Krack P, Kaufmann P, Mazzoni P (2008). "Historical underpinnings of the term essential tremor in the late 19th century". Neurology. 71 (11): 856–9. doi:10.1212/01.wnl.0000325564.38165.d1. PMC 3461999. PMID 18779514.
  4. ↑ Kosmowska B, Wardas J (2021). "The Pathophysiology and Treatment of Essential Tremor: The Role of Adenosine and Dopamine Receptors in Animal Models". Biomolecules. 11 (12). doi:10.3390/biom11121813. PMC 8698799 Check |pmc= value (help). PMID 34944457 Check |pmid= value (help).
  5. ↑ Higgins JJ, Lombardi RQ, Pucilowska J, Jankovic J, Tan EK, Rooney JP (2005). "A variant in the HS1-BP3 gene is associated with familial essential tremor". Neurology. 64 (3): 417–21. doi:10.1212/01.WNL.0000153481.30222.38. PMC 1201396. PMID 15699368.
  6. ↑ Thier S, Lorenz D, Nothnagel M, Poremba C, Papengut F, Appenzeller S; et al. (2012). "Polymorphisms in the glial glutamate transporter SLC1A2 are associated with essential tremor". Neurology. 79 (3): 243–8. doi:10.1212/WNL.0b013e31825fdeed. PMC 3398434. PMID 22764253.
  7. ↑ Unal Gulsuner H, Gulsuner S, Mercan FN, Onat OE, Walsh T, Shahin H; et al. (2014). "Mitochondrial serine protease HTRA2 p.G399S in a kindred with essential tremor and Parkinson disease". Proc Natl Acad Sci U S A. 111 (51): 18285–90. doi:10.1073/pnas.1419581111. PMC 4280582. PMID 25422467.
  8. ↑ Louis ED, Jurewicz EC, Applegate L, Factor-Litvak P, Parides M, Andrews L; et al. (2003). "Association between essential tremor and blood lead concentration". Environ Health Perspect. 111 (14): 1707–11. doi:10.1289/ehp.6404. PMC 1241711. PMID 14594619.
  9. ↑ Shalash AS, Hamid E, Elrassas H, Bahbah EI, Mansour AH, Mohamed H; et al. (2021). "Non-motor symptoms in essential tremor, akinetic rigid and tremor-dominant subtypes of Parkinson's disease". PLoS One. 16 (1): e0245918. doi:10.1371/journal.pone.0245918. PMC 7840014 Check |pmc= value (help). PMID 33503062 Check |pmid= value (help).
  10. ↑ 10.0 10.1 Gerbasi ME, Elble RJ, Jones E, Gillespie A, Jarvis J, Chertavian E; et al. (2024). "Associations Among Tremor Amplitude, Activities of Daily Living, and Quality of Life in Patients with Essential Tremor". Tremor Other Hyperkinet Mov (N Y). 14: 22. doi:10.5334/tohm.877. PMC 11067966 Check |pmc= value (help). PMID 38708124 Check |pmid= value (help).
  11. ↑ Kim YW, Kim S, Jin MJ, Im CH, Lee SH (2024). "The Importance of Low-frequency Alpha (8-10 Hz) Waves and Default Mode Network in Behavioral Inhibition". Clin Psychopharmacol Neurosci. 22 (1): 53–66. doi:10.9758/cpn.22.1035. PMC 10811390 Check |pmc= value (help). PMID 38247412 Check |pmid= value (help).
  12. ↑ Antonazzo IC, Rozza D, Conti S, Fornari C, Cortesi PA, Eteve-Pitsaer C; et al. (2024). "Treatment patterns in essential tremor: Real-world evidence from the United Kingdom and France primary care database". Eur J Neurol. 31 (1): e16064. doi:10.1111/ene.16064. PMID 37738526 Check |pmid= value (help).
  13. ↑ Zhang M, Li W, Hu L, Chen L, Yang L, Zhang T; et al. (2020). "Oral propranolol for treatment of the subgroups of essential tremor: a systematic review and meta-analysis protocol". BMJ Open. 10 (1): e032096. doi:10.1136/bmjopen-2019-032096. PMC 7044890 Check |pmc= value (help). PMID 31948986.

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