Editing Essential tremor (section)

==Signs and symptoms==
The tremors linked with essential tremor are generally action tremors, which means they occur during intentional movements rather than when the body is at rest.<ref>{{cite journal | vauthors = Lenka A, Jankovic J | title = Tremor Syndromes: An Updated Review | journal = Frontiers in Neurology | volume = 12 | pages = 684835 | date = 2021-07-26 | pmid = 34381412 | pmc = 8350038 | doi = 10.3389/fneur.2021.684835 | doi-access = free }}</ref>

In mild cases, ET can manifest as the inability to stop the tongue or hands from shaking, the ability to sing only in [[vibrato]], and difficulty doing small, precise tasks such as threading a needle. Even simple tasks such as cutting in a straight line or using a ruler can range from difficult to impossible, depending on the severity of the condition. In disabling cases, ET can interfere with a person's [[activities of daily living]], including feeding, dressing, and taking care of personal hygiene. Essential tremor generally presents as a rhythmic tremor (4–12 [[Hertz|Hz]]) that occurs only when the affected [[muscle]] is exerting effort. Any sort of physical or mental [[stress (medicine)|stress]] tends to make the tremor worse.<ref name="hopkinsmedicine">{{cite web | title = Essential Tremor Treatment at the Johns Hopkins Movement Disorders Center in Baltimore, MD | publisher = hopkinsmedicine.org | url = http://www.hopkinsmedicine.org/neurology_neurosurgery/specialty_areas/movement_disorders/conditions/essential_tremor.html | access-date = 27 October 2014 }}</ref>

The tremor may also occur in the head (neck), jaw, and voice, as well as other body regions, with the general pattern being that the tremor begins in the arms and then spreads to these other regions in some people. Women are more likely to develop the head tremor than are men, and it is also found to be more severe in women than men.<ref>{{cite journal | vauthors = Hardesty DE, Maraganore DM, Matsumoto JY, Louis ED | title = Increased risk of head tremor in women with essential tremor: longitudinal data from the Rochester Epidemiology Project | journal = Movement Disorders | volume = 19 | issue = 5 | pages = 529–533 | date = May 2004 | pmid = 15133816 | doi = 10.1002/mds.20096 }}</ref><ref name="pubmed.ncbi.nlm.nih.gov">{{cite journal | vauthors = Hubble JP, Busenbark KL, Pahwa R, Lyons K, Koller WC | title = Clinical expression of essential tremor: effects of gender and age | journal = Movement Disorders | volume = 12 | issue = 6 | pages = 969–972 | date = November 1997 | pmid = 9399222 | doi = 10.1002/mds.870120620 }}</ref> In people with essential tremor (ET), the head tremor can be either vertical ("yes-yes") or horizontal ("no-no") and is typically accompanied by tremors in the hands or voice.<ref>{{cite journal | vauthors = Louis ED, Dogu O | title = Isolated head tremor: part of the clinical spectrum of essential tremor? Data from population-based and clinic-based case samples | journal = Movement Disorders | volume = 24 | issue = 15 | pages = 2281–2285 | date = November 2009 | pmid = 19795473 | pmc = 2839188 | doi = 10.1002/mds.22777 }}</ref> Other types of tremor may also occur, including postural tremor of the outstretched arms, [[intention tremor]] of the arms, and rest tremor in the arms.<ref>{{cite journal | vauthors = Louis ED | title = Clinical practice. Essential tremor | journal = The New England Journal of Medicine | volume = 345 | issue = 12 | pages = 887–891 | date = September 2001 | pmid = 11565522 | doi = 10.1056/nejmcp010928 }}</ref> In one study, men had more severe postural hand tremor when compared to women.<ref name="pubmed.ncbi.nlm.nih.gov"/> Some people may have unsteadiness and problems with gait and balance.<ref name="pmid20926368">{{cite journal | vauthors = Fasano A, Herzog J, Raethjen J, Rose FE, Muthuraman M, Volkmann J, Falk D, Elble R, Deuschl G | title = Gait ataxia in essential tremor is differentially modulated by thalamic stimulation | journal = Brain | volume = 133 | issue = Pt 12 | pages = 3635–3648 | date = December 2010 | pmid = 20926368 | doi = 10.1093/brain/awq267 | doi-access = free }}</ref> Abnormal tandem gait was more commonly observed in older ET people and those with more than 5 years of disease duration.<ref>{{cite journal | vauthors = Singer C, Sanchez-Ramos J, Weiner WJ | title = Gait abnormality in essential tremor | journal = Movement Disorders | volume = 9 | issue = 2 | pages = 193–196 | date = March 1994 | pmid = 8196682 | doi = 10.1002/mds.870090212 }}</ref>

ET-related tremors do not occur during sleep, but people with ET sometimes complain of an especially coarse tremor upon awakening that becomes noticeably less coarse within the first few minutes of wakefulness. Tremor and disease activity can intensify in response to fatigue, strong emotions, [[low blood sugar]], extreme cold and heat, [[caffeine]], [[lithium salt]]s, some [[antidepressant]]s, [[Stress (biology)|stress]], and other factors.<ref name="pmid23591755">{{cite journal | vauthors = Elble RJ | title = What is essential tremor? | journal = Current Neurology and Neuroscience Reports | volume = 13 | issue = 6 | pages = 353 | date = June 2013 | pmid = 23591755 | pmc = 3674100 | doi = 10.1007/s11910-013-0353-4 }}</ref>

Parkinson's disease and parkinsonism can also occur simultaneously with ET.<ref name=Abboud/> The degree of tremor, rigidity, and functional disability did not differ from patients with idiopathic Parkinson's disease. Hand tremor predominated (as it did in Parkinson's disease), and occurred in nearly all cases, followed by head tremor, voice tremor, neck, face, leg, tongue, and trunk tremor. Most other tremors occurred in association with hand tremor. More severe tremors, a lower sleep disorder frequency, and a similar prevalence of other non-motor symptoms also can occur.<ref>{{cite journal | vauthors = Ryu DW, Lee SH, Oh YS, An JY, Park JW, Song IU, Lee KS, Kim JS | title = Clinical Characteristics of Parkinson's Disease Developed from Essential Tremor | journal = Journal of Parkinson's Disease | volume = 7 | issue = 2 | pages = 369–376 | date = 2017-05-16 | pmid = 28409750 | doi = 10.3233/JPD-160992 }}</ref> A non-motor feature such as hearing impairment has been shown to have higher prevalence in those with ET compared with those that are healthy or with Parkinson's. Cochlear pathologies which affect the inner ear are proposed as the potential cause, but there is still insufficient information regarding retrocochlear pathologies (affects central or neural nerve) and central auditory processing.<ref name="Correlation between essential tremo">{{cite journal | vauthors = Biary N, Koller W, Langenberg P | title = Correlation between essential tremor and migraine headache | journal = Journal of Neurology, Neurosurgery, and Psychiatry | volume = 53 | issue = 12 | pages = 1060–1062 | date = December 1990 | pmid = 2292698 | pmc = 488315 | doi = 10.1136/jnnp.53.12.1060 }}</ref>

Walking difficulties in essential tremor are common. About half of patients have associated [[dystonia]], including [[Spasmodic torticollis|cervical dystonia]], [[writer's cramp]], [[spasmodic dysphonia]], and cranial dystonia, and 20% of the patients had associated parkinsonism. Olfactory dysfunction (loss of sense of smell) is common in Parkinson's disease, and has also been reported to occur in patients with essential tremor. A number of patients with essential tremor also exhibit many of the same neuropsychiatric disturbances seen in idiopathic Parkinson's disease.<ref name="pmid8334571">{{cite journal | vauthors = Rajput AH, Rozdilsky B, Ang L, Rajput A | title = Significance of parkinsonian manifestations in essential tremor | journal = The Canadian Journal of Neurological Sciences. Le Journal Canadien des Sciences Neurologiques | volume = 20 | issue = 2 | pages = 114–117 | date = May 1993 | pmid = 8334571 | doi = 10.1017/s031716710004765x | id = {{INIST|4838591}} | doi-access = free }}</ref> The similarity in characteristics between parkinsonism and essential tremor can make it difficult to distinguish between the two at times.<ref name="Abboud" />

Essential tremor with tremor onset after the age of 65 has been associated with mild cognitive impairment,<ref name=pmid21304183>{{cite journal | vauthors = Benito-León J, Louis ED, Mitchell AJ, Bermejo-Pareja F | title = Elderly-onset essential tremor and mild cognitive impairment: a population-based study (NEDICES) | journal = Journal of Alzheimer's Disease | volume = 23 | issue = 4 | pages = 727–735 | year = 2011 | pmid = 21304183 | doi = 10.3233/JAD-2011-101572 }}</ref> as well as [[dementia]], although the link between these conditions, if any, is still not understood.<ref name=pmid16717208>{{cite journal | vauthors = Benito-León J, Louis ED, Bermejo-Pareja F | title = Elderly-onset essential tremor is associated with dementia | journal = Neurology | volume = 66 | issue = 10 | pages = 1500–1505 | date = May 2006 | pmid = 16717208 | doi = 10.1212/01.wnl.0000216134.88617.de | s2cid = 34434554 }}</ref><ref name="NCBI3">{{cite journal | vauthors = 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 | volume = 29 | issue = 3–4 | pages = 208–212 | date = October 1987 | pmid = 18043006 | pmc = 2824583 | doi = 10.3168/jds.S0022-0302(87)80259-X }}</ref> Familial cases of ET tend to present at younger ages, whereas older ages of onset are linked to faster progression of the disease.<ref>{{cite journal | vauthors = Louis ED | title = The Roles of Age and Aging in Essential Tremor: An Epidemiological Perspective | journal = Neuroepidemiology | volume = 52 | issue = 1–2 | pages = 111–118 | date = 2019 | pmid = 30625472 | doi = 10.1159/000492831 }}</ref>

Essential tremor has two tremor components, central and peripheral. These two tremor components were identified by measuring the tremor of ET patients once with no weights on their hands and then with 1-pound weights on their hands. The addition of the weights resulted in a tremor spectrum with two peaks, one that maintained the same frequency (the central tremor) and one that decreased in frequency (the peripheral tremor). Only with the addition of the weights was the peripheral tremor distinguishable from the central tremor.<ref name="Cao_2018">{{cite journal | vauthors = Cao H, Thompson-Westra J, Hallett M, Haubenberger D | title = The response of the central and peripheral tremor component to octanoic acid in patients with essential tremor | journal = Clinical Neurophysiology | volume = 129 | issue = 7 | pages = 1467–1471 | date = July 2018 | pmid = 29678370 | pmc = 6530908 | doi = 10.1016/j.clinph.2018.03.016 }}</ref>

The frequency of essential tremor is 4 to 12&nbsp;Hz, depending on which body segment is affected.<ref>{{cite web | vauthors = Liang TW, Hurtig H |title=Medical management of motor fluctuations and dyskinesia in Parkinson disease |url=https://www.uptodate.com/contents/medical-management-of-motor-fluctuations-and-dyskinesia-in-parkinson-disease |work=UpToDate }}</ref> Previously, it was 4 to 11&nbsp;Hz according to the American Family Physician on Classification of Tremors and Treatment Update.<ref>{{cite journal | vauthors = Charles PD, Esper GJ, Davis TL, Maciunas RJ, Robertson D | title = Classification of tremor and update on treatment | journal = American Family Physician | volume = 59 | issue = 6 | pages = 1565–1572 | date = March 1999 | pmid = 10193597 | url = https://www.aafp.org/pubs/afp/issues/1999/0315/p1565.html }}</ref> Proximal segments are affected at lower frequencies, and distal segments are affected at higher frequencies.<ref>{{cite journal | vauthors = Bracker MD | title = A Skin-Deep Diagnosis | journal = The Physician and Sportsmedicine | volume = 22 | issue = 12 | pages = 79–82 | date = December 1994 | pmid = 29272964 | doi = 10.1080/00913847.1994.11947721 }}</ref>