Essential tremor (ET), also called benign tremor, familial tremor, and idiopathic tremor, is a medical condition characterized by involuntary rhythmic contractions and relaxations (
oscillations or twitching movements) of certain muscle groups in one or more body parts of unknown cause. It is typically symmetrical, and affects the arms, hands, or fingers; but sometimes involves the head, vocal cords, or other body parts.
Essential tremor is either an ''action'' (intention) tremor—it intensifies when one tries to use the affected muscles during voluntary movements such as eating and writing—or it is a ''postural'' tremor, present with sustained muscle tone. This means that it is distinct from a
resting tremor, such as that caused by
Parkinson's disease
Parkinson's disease (PD), or simply Parkinson's, is a long-term degenerative disorder of the central nervous system that mainly affects the motor system. The symptoms usually emerge slowly, and as the disease worsens, non-motor symptoms beco ...
, which is not correlated with movement.
Essential tremor is a
progressive neurological disorder
A neurological disorder is any disorder of the nervous system. Structural, biochemical or electrical abnormalities in the brain, spinal cord or other nerves can result in a range of symptoms. Examples of symptoms include paralysis, muscle weakn ...
, and the most common
movement disorder
Movement disorder refers to any clinical syndrome with either an excess of movement or a paucity of voluntary and involuntary movements, unrelated to weakness or spasticity. Movement disorders are synonymous with basal ganglia or extrapyramidal ...
. Its onset is usually after age 40, but it can occur at any age.
The cause is unknown. Diagnosis is by observing the typical pattern of the tremor coupled with the exclusion of known causes of such a tremor.
While essential tremor is distinct from Parkinson's disease, which causes a resting tremor, essential tremor is nevertheless sometimes misdiagnosed as Parkinson's disease.
[ Some patients have been found to have both essential tremors and resting tremors.][
Treatments for essential tremor include medications, typically given sequentially to determine which provides the best compromise between effectiveness and troublesome side effects. ''Clostridium botulinum'' toxin (Botox) injections and ultrasound are also sometimes used for cases refractory to medications.
]
Signs and symptoms
In mild cases, ET can manifest as the inability to stop the tongue or hands from shaking, the ability to sing only in vibrato
Vibrato (Italian language, Italian, from past participle of "wikt:vibrare, vibrare", to vibrate) is a musical effect consisting of a regular, pulsating change of pitch (music), pitch. It is used to add expression to vocal and instrumental music. ...
, 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
Activity may refer to:
* Action (philosophy), in general
* Human activity: human behavior, in sociology behavior may refer to all basic human actions, economics may study human economic activities and along with cybernetics and psychology may st ...
, including feeding, dressing, and taking care of personal hygiene. Essential tremor generally presents as a rhythmic tremor (4–12 Hz) that occurs only when the affected muscle
Skeletal muscles (commonly referred to as muscles) are organs of the vertebrate muscular system and typically are attached by tendons to bones of a skeleton. The muscle cells of skeletal muscles are much longer than in the other types of muscl ...
is exerting effort. Any sort of physical or mental stress
Stress may refer to:
Science and medicine
* Stress (biology), an organism's response to a stressor such as an environmental condition
* Stress (linguistics), relative emphasis or prominence given to a syllable in a word, or to a word in a phrase ...
tends to make the tremor worse.
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. Other types of tremor may also occur, including postural tremor of the outstretched arms, intention tremor
Intention tremor is a dyskinetic disorder characterized by a broad, coarse, and low frequency (below 5 Hz) tremor evident during deliberate and visually-guided movement (hence the name intention tremor). An intention tremor is usually perpendi ...
of the arms, and rest tremor in the arms. Some people may have unsteadiness and problems with gait and balance.
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/intensity can worsen in response to fatigue, strong emotions, low blood sugar
Hypoglycemia, also called low blood sugar, is a fall in blood sugar to levels below normal, typically below 70 mg/dL (3.9 mmol/L). Whipple's triad is used to properly identify hypoglycemic episodes. It is defined as blood glucose belo ...
, cold and heat, caffeine
Caffeine is a central nervous system (CNS) stimulant of the methylxanthine class. It is mainly used recreationally as a cognitive enhancer, increasing alertness and attentional performance. Caffeine acts by blocking binding of adenosine t ...
, lithium salt
Lithium (from el, λίθος, lithos, lit=stone) is a chemical element with the symbol Li and atomic number 3. It is a soft, silvery-white alkali metal. Under standard conditions, it is the least dense metal and the least dense solid e ...
s, some antidepressant
Antidepressants are a class of medication used to treat major depressive disorder, anxiety disorders, chronic pain conditions, and to help manage addictions. Common side-effects of antidepressants include dry mouth, weight gain, dizziness, hea ...
s, and other factors. Typically, the tremor worsens in "performance" situations, such as when writing a cheque for payment at a store or giving a presentation.
Parkinson's disease and parkinsonism can also occur simultaneously with ET.[ 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.
Walking difficulties in essential tremor are common. About half of patients have associated ]dystonia
Dystonia is a neurological hyperkinetic movement disorder in which sustained or repetitive muscle contractions result in twisting and repetitive movements or abnormal fixed postures. The movements may resemble a tremor. Dystonia is often inten ...
, including cervical dystonia
Spasmodic torticollis is an extremely painful chronic neurological movement disorder causing the neck to involuntarily turn to the left, right, upwards, and/or downwards. The condition is also referred to as "cervical dystonia". Both agonist and ...
, writer's cramp
Writer's cramp or focal hand dystonia (FHD) is an idiopathic movement disorder of adult onset, characterized by abnormal posturing and movement of the hand and/or forearm during tasks requiring skilled hand use, such as writing.Rana, AQ, Saeed, U. ...
, spasmodic dysphonia
Spasmodic dysphonia, also known as laryngeal dystonia, is a disorder in which the muscles that generate a person's voice go into periods of spasm. This results in breaks or interruptions in the voice, often every few sentences, which can make a pe ...
, 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.
Essential tremor with tremor onset after the age of 65 has been associated with mild cognitive impairment, as well as dementia
Dementia is a disorder which manifests as a set of related symptoms, which usually surfaces when the brain is damaged by injury or disease. The symptoms involve progressive impairments in memory, thinking, and behavior, which negatively affe ...
; although the link between these conditions, if any, is still not understood.
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-lb 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.
The frequency of essential tremor is 4 to 11 Hz, depending on which body segment is affected. Proximal segments are affected at lower frequencies, and distal segments are affected at higher frequencies
Cause
Genetic
The underlying cause of essential tremor is not clear, but many cases seem to be familial. About half of the cases are due to a genetic mutation and the pattern of inheritance is most consistent with autosomal
An autosome is any chromosome that is not a sex chromosome. The members of an autosome pair in a diploid cell have the same morphology, unlike those in allosome, allosomal (sex chromosome) pairs, which may have different structures. The DNA in au ...
dominant transmission. No genes have been identified yet, but genetic linkage
Genetic linkage is the tendency of DNA sequences that are close together on a chromosome to be inherited together during the meiosis phase of sexual reproduction. Two genetic markers that are physically near to each other are unlikely to be separ ...
has been established with several chromosomal regions.
Toxins
Some environmental factors, including toxins, are also under active investigation, as they may play a role in the disease's cause.
Pathophysiology
In terms of pathophysiology, clinical, physiological and imaging studies point to an involvement of the cerebellum
The cerebellum (Latin for "little brain") is a major feature of the hindbrain of all vertebrates. Although usually smaller than the cerebrum, in some animals such as the mormyrid fishes it may be as large as or even larger. In humans, the cerebel ...
and/or cerebellothalamocortical The cerebellothalamic tract or the ''tractus cerebellothalamicus'', is part of the superior cerebellar peduncle. It originates in the cerebellar nuclei, crosses completely in the decussation of the superior cerebellar peduncle, bypasses the red nu ...
circuits. Changes in the cerebellum could also be mediated by alcoholic beverage consumption. Purkinje cell
Purkinje cells, or Purkinje neurons, are a class of GABAergic inhibitory neurons located in the cerebellum. They are named after their discoverer, Czech people, Czech anatomist Jan Evangelista Purkyně, who characterized the cells in 1839.
Stru ...
s are especially susceptible to ethanol excitotoxicity
In excitotoxicity, nerve cells suffer damage or death when the levels of otherwise necessary and safe neurotransmitters such as glutamate become pathologically high, resulting in excessive stimulation of receptors. For example, when glutamate re ...
. Impairment of Purkinje synapses is a component of cerebellar degradation that could underlie essential tremor. Some cases have Lewy bodies
Lewy bodies are the inclusion bodies – abnormal aggregations of protein – that develop inside nerve cells affected by Parkinson's disease (PD), the Lewy body dementias ( Parkinson's disease dementia and dementia with Lewy bodies (DLB)), and ...
in the locus ceruleus
The locus coeruleus () (LC), also spelled locus caeruleus or locus ceruleus, is a nucleus in the pons of the brainstem involved with physiological responses to stress and panic. It is a part of the reticular activating system.
The locus coeru ...
. ET cases that progress to Parkinson's disease are less likely to have had cerebellar problems. Recent neuroimaging studies have suggested that the efficiency of the overall brain functional network in ET is disrupted.
Recent ''post mortem'' studies have evidenced alterations in (leucine-rich repeat and Ig domain containing 1 (''LINGO1
Leucine rich repeat and Immunoglobin-like domain-containing protein 1 also known as LINGO-1 is a protein which is encoded by the ''LINGO1'' gene in humans. It belongs to the family of leucine-rich repeat proteins which are known for playing key rol ...
'') gene and GABA receptors in the cerebellum of people with essential tremor. ''HAPT1 ''mutations have also been linked to ET, as well as to Parkinson's disease, multiple system atrophy
Multiple system atrophy (MSA) is a rare neurodegenerative disorder characterized by autonomic dysfunction, tremors, slow movement, muscle rigidity, and postural instability (collectively known as parkinsonism) and ataxia. This is caused by progr ...
, and progressive supranuclear palsy
Progressive supranuclear palsy (PSP) is a late-onset degenerative disease involving the gradual deterioration and death of specific volumes of the brain. The condition leads to symptoms including loss of balance, slowing of movement, difficulty ...
.
In 2012, the National Toxicology Program concluded that sufficient evidence exists of an association between blood lead exposure at levels >10 μg/dl and essential tremor in adults, and limited evidence at blood lead levels >5 μg/dl.
Diagnosis
Usually, the diagnosis is established on clinical grounds. Tremors can start at any age, from birth through advanced ages (senile tremor). Any voluntary muscle in the body may be affected, although the tremor is most commonly seen in the hands and arms and slightly less commonly in the neck
The neck is the part of the body on many vertebrates that connects the head with the torso. The neck supports the weight of the head and protects the nerves that carry sensory and motor information from the brain down to the rest of the body. In ...
(causing the person's head to shake), tongue
The tongue is a muscular organ (anatomy), organ in the mouth of a typical tetrapod. It manipulates food for mastication and swallowing as part of the digestive system, digestive process, and is the primary organ of taste. The tongue's upper surfa ...
, and legs. A resting tremor of the hands is sometimes present.[ Tremor occurring in the legs might be diagnosable as orthostatic tremor.
ET occurs within multiple neurological disorders besides Parkinson's disease. This includes migraine disorders, where co-occurrences between ET and migraines have been examined.
]
Treatment
General measures
Not all individuals with ET require treatment, but many treatment options are available depending on symptom severity.[ Caffeine and stress should be avoided, and adequate good-quality sleep is recommended.][
]
Oral medications
First-line
When symptoms are sufficiently troublesome to warrant treatment, the first medication choices are beta blockers
Beta blockers, also spelled β-blockers, are a class of medications that are predominantly used to manage cardiac arrhythmia, abnormal heart rhythms, and to protect the heart from a second myocardial infarction, heart attack after a first heart ...
such as propranolol
Propranolol, sold under the brand name Inderal among others, is a medication of the beta blocker class. It is used to treat high blood pressure, a number of types of irregular heart rate, thyrotoxicosis, capillary hemangiomas, performance anx ...
or alternately, nadolol
Nadolol, sold under the brand name Corgard among others, is a medication used to treat high blood pressure, heart pain, atrial fibrillation, and some inherited arrhythmic syndromes. It has also been used to prevent migraine headaches and compl ...
and timolol
Timolol is a beta blocker medication used either by mouth or as eye drops. As eye drops it is used to treat increased pressure inside the eye such as in ocular hypertension and glaucoma. By mouth it is used for high blood pressure, chest pa ...
. Atenolol
Atenolol is a beta blocker medication primarily used to treat high blood pressure and heart-associated chest pain. Atenolol, however, does not seem to improve mortality in those with high blood pressure. Other uses include the prevention of mi ...
and pindolol
Pindolol, sold under the brand name Visken among others, is a nonselective beta blocker which is used in the treatment of hypertension.Drugs.coInternational brand names for pindolol Page accessed Sept 4, 2015 It is also an antagonist of the se ...
are not effective for tremor.[ The anticonvulsant ]primidone
Primidone, sold under various brand names, is a barbiturate medication that is used to treat partial and generalized seizures, as well as essential tremors. It is taken by mouth.
Common side effects include sleepiness, poor coordination, nau ...
may also be effective.[ ET is generally responsive to ]alcohol
Alcohol most commonly refers to:
* Alcohol (chemistry), an organic compound in which a hydroxyl group is bound to a carbon atom
* Alcohol (drug), an intoxicant found in alcoholic drinks
Alcohol may also refer to:
Chemicals
* Ethanol, one of sev ...
, but the risks of regular drinking are greater than the potential benefit. Nonetheless, ET patients sometimes self-medicate with alcohol.
Propranolol and primidone only have tremor-reducing effects on about half of ET patients, and the effects are moderate.
Second-line
Second-line medications are the anticonvulsants topiramate
Topiramate, sold under the brand name Topamax among others, is a carbonic anhydrase inhibitor medication used to treat epilepsy and prevent migraines. It has also been used in alcohol dependence. For epilepsy this includes treatment for gener ...
, gabapentin
Gabapentin, sold under the brand name Neurontin among others, is an anticonvulsant medication primarily used to treat partial seizures and neuropathic pain. It is a first-line medication for the treatment of neuropathic pain caused by diabet ...
(as monotherapy) or levetiracetam
Levetiracetam, sold under the brand name Keppra among others, is a medication used to treat epilepsy. It is used for partial-onset, myoclonic, or tonic–clonic seizures and is taken either by mouth as an immediate or extended release formu ...
, or benzodiazepines such as alprazolam
Alprazolam, sold under the brand name Xanax, among others, is a fast-acting, potent tranquilizer of medium duration in the triazolobenzodiazepine (TBZD) class, which are benzodiazepines (BZDs) fused with a triazole ring. It is most commonly u ...
.
Third-line
Third-line medications are clonazepam
Clonazepam, sold under the brand names Klonopin and Rivotril, is a medication used to prevent and treat seizures, panic disorder, anxiety disorders, and the movement disorder known as akathisia. It is a tranquilizer of the benzodiazepine class ...
and mirtazapine
Mirtazapine, sold under the brand name Remeron amongst others, is an atypical antidepressant, and as such is used primarily to treat depression. Its effects may take up to four weeks, but can also manifest as early as one to two weeks. It is o ...
.[
]
Fourth-line
Theophylline
Theophylline, also known as 1,3-dimethylxanthine, is a phosphodiesterase inhibiting drug used in therapy for respiratory diseases such as chronic obstructive pulmonary disease (COPD) and asthma under a variety of brand names. As a member of the ...
has been used by some practitioners to treat ET, though it may also induce tremor. However, its use is debated due to conflicting data on its efficacy. Some evidence shows that low doses may lead to improvement.
Ethanol
Ethanol (abbr. EtOH; also called ethyl alcohol, grain alcohol, drinking alcohol, or simply alcohol) is an organic compound. It is an Alcohol (chemistry), alcohol with the chemical formula . Its formula can be also written as or (an ethyl ...
has shown superior efficacy to those of benzodiazepines in small trials. It improves tremor in small doses and its effects are usually noticeable within 20 minutes for 3–5 hours, but occasionally appears in a rebound tremor augmentation later.
Some systematic reviews of medications for the treatment of ET have been conducted. A 2017 review of topiramate
Topiramate, sold under the brand name Topamax among others, is a carbonic anhydrase inhibitor medication used to treat epilepsy and prevent migraines. It has also been used in alcohol dependence. For epilepsy this includes treatment for gener ...
found limited data and low quality evidence to support its efficacy and the occurrence of treatment-limiting adverse effects, a 2017 review of zonisamide
Zonisamide, sold under the brand name Zonegran among others, is a medication used to treat the symptoms of epilepsy and Parkinson's disease. Chemically it is a sulfonamide. It serves as an anticonvulsant used primarily as an adjunctive therapy ...
found insufficient information to assess efficacy and safety, and a 2016 review of pregabalin
Pregabalin, sold under the brand name Lyrica among others, is an anticonvulsant, analgesic and anxiolytic medication used to treat epilepsy, neuropathic pain, fibromyalgia, restless leg syndrome, opioid withdrawal and generalized anxiety disord ...
determined the effects to be uncertain due to the low quality of evidence.
Botulinum injection
When medications do not control the tremor or the person does not tolerate medication, ''C. botulinum'' toxin, deep brain stimulation
Deep brain stimulation (DBS) is a neurosurgical procedure involving the placement of a medical device called a neurostimulator, which sends electrical impulses, through implanted electrodes, to specific targets in the brain (the brain nucleu ...
, or occupational therapy can be helpful.[ The electrodes for deep brain stimulation are usually placed in the "tremor center" of the brain, the ventral intermediate nucleus of the ]thalamus
The thalamus (from Greek θάλαμος, "chamber") is a large mass of gray matter located in the dorsal part of the diencephalon (a division of the forebrain). Nerve fibers project out of the thalamus to the cerebral cortex in all directions, ...
.
Ultrasound
Additionally, MRI
Magnetic resonance imaging (MRI) is a medical imaging technique used in radiology to form pictures of the anatomy and the physiological processes of the body. MRI scanners use strong magnetic fields, magnetic field gradients, and radio waves ...
-guided high-intensity focused ultrasound
High-intensity focused ultrasound (HIFU) is a non-invasive therapeutic technique that uses non-ionizing ultrasonic waves to heat or ablate tissue. HIFU can be used to increase the flow of blood or lymph or to destroy tissue, such as tumors, vi ...
is a nonsurgical treatment option for people with essential tremor who are medication refractory.[FDA News Release]
"FDA approves first MRI-guided focused ultrasound device to treat essential tremor"
''FDA
The United States Food and Drug Administration (FDA or US FDA) is a federal agency of the Department of Health and Human Services. The FDA is responsible for protecting and promoting public health through the control and supervision of food ...
'', July 11, 2016 MRI-guided high-intensity focused ultrasound does not achieve healing, but can improve the quality of life. While its long-term effects are not yet established, the improvement in tremor score from baseline was durable at 1 year and 2 years following the treatment. To date, reported adverse events and side effects have been mild to moderate. Possible adverse events include gait difficulties, balance disturbances, paresthesia
Paresthesia is an abnormal sensation of the skin (tingling, pricking, chilling, burning, numbness) with no apparent physical cause. Paresthesia may be transient or chronic, and may have any of dozens of possible underlying causes. Paresthesias ar ...
s, headache
Headache is the symptom of pain in the face, head, or neck. It can occur as a migraine, tension-type headache, or cluster headache. There is an increased risk of depression in those with severe headaches.
Headaches can occur as a result ...
, skin burns with ulcerations, skin retraction, scars, and blood clots. This procedure is contraindicated in pregnant women, persons who have non-MRI compatible implanted metallic devices, allergy to MR contrast agents, cerebrovascular disease, abnormal bleeding, hemorrhage and/or blood clotting disorders, advanced kidney disease or on dialysis, heart conditions, severe hypertension, and ethanol or substance abuse, among others. The US Food and Drug Administration (FDA
The United States Food and Drug Administration (FDA or US FDA) is a federal agency of the Department of Health and Human Services. The FDA is responsible for protecting and promoting public health through the control and supervision of food ...
) approved Insightec's Exablate Neuro system to treat essential tremor in 2016.
Another treatment for essential tremor is a surgical option; deep brain stimulation is used.
Prognosis
Although essential tremor is often mild, people with severe tremor have difficulty performing many of their routine activities of daily living. ET is generally progressive in most cases (sometimes rapidly, sometimes very slowly), and can be disabling in severe cases.
Epidemiology
ET is one of the most common neurological diseases, with a prevalence around 4% in persons age 40 and older and considerably higher among persons in their 60s, 70s, and 80s, with an estimated 20% of individuals in their 90s and over. Aside from enhanced physiological tremor, it is the most common type of tremor
A tremor is an involuntary, somewhat rhythmic, muscle contraction and relaxation involving oscillations or twitching movements of one or more body parts. It is the most common of all involuntary movements and can affect the hands, arms, eyes, fa ...
and one of the most commonly observed movement disorders.
Society and culture
Actress Katharine Hepburn
Katharine Houghton Hepburn (May 12, 1907 – June 29, 2003) was an American actress in film, stage, and television. Her career as a Hollywood leading lady spanned over 60 years. She was known for her headstrong independence, spirited perso ...
(1907–2003) had an essential tremor, possibly inherited from her grandfather, that caused her head—and sometimes her hands—to shake. The tremor was noticeable by the time of her performance in the 1979 film ''The Corn Is Green
''The Corn Is Green'' is a 1938 semi-autobiographical play by Welsh dramatist and actor Emlyn Williams. The play premiered in London at the Duchess Theatre in September 1938; with Sybil Thorndike as Miss Moffat and Williams himself portraying Mo ...
'', when critics mentioned the "palsy that kept her head trembling". Hepburn's tremor worsened in her later life.[
]Charles M. Schulz
Charles Monroe "Sparky" Schulz (; November 26, 1922 – February 12, 2000) was an American cartoonist and the creator of the comic strip ''Peanuts'', featuring what are probably his two best-known characters, Charlie Brown and Snoopy. He is wi ...
, American cartoonist and creator of the ''Peanuts
''Peanuts'' is a print syndication, syndicated daily strip, daily and Sunday strip, Sunday American comic strip written and illustrated by Charles M. Schulz. The strip's original run extended from 1950 to 2000, continuing in reruns afterward. ' ...
'' comic strip, was affected during the last two decades of his life.
West Virginia
West Virginia is a state in the Appalachian, Mid-Atlantic and Southeastern regions of the United States.The Census Bureau and the Association of American Geographers classify West Virginia as part of the Southern United States while the Bur ...
Senator Robert Byrd
Robert Carlyle Byrd (born Cornelius Calvin Sale Jr.; November 20, 1917 – June 28, 2010) was an American politician and musician who served as a United States senator from West Virginia for over 51 years, from 1959 until his death in 2010. A ...
also had essential tremor.
In 2010, musician Daryl Dragon
Daryl Frank Dragon (August 27, 1942 – January 2, 2019) was an American musician, known as Captain from the pop musical duo Captain & Tennille with his then-wife, Toni Tennille.
Career
Born into a musical family, Dragon was the son of El ...
of The Captain and Tennille was diagnosed with essential tremor, with the condition becoming so severe that Dragon was no longer able to play the keyboards.
Director-writer-producer-comedian Adam McKay was diagnosed with essential tremor.
Downton Abbey
''Downton Abbey'' is a British historical drama television series set in the early 20th century, created and co-written by Julian Fellowes. The series first aired in the United Kingdom on ITV on 26 September 2010 and in the United States on P ...
creator Julian Fellowes
Julian Alexander Kitchener-Fellowes, Baron Fellowes of West Stafford, (born 17 August 1949) is an English actor, novelist, film director and screenwriter, and a Conservative peer of the House of Lords.
He is primarily known as the author of s ...
has the condition, as does the show's character Charlie Carson.
In 2022, Matthew Caws
Matthew Rorison Caws (born August 5, 1967) is an American singer, songwriter and guitarist. He is best known as the lead vocalist and guitarist of the alternative rock band Nada Surf. Caws is also a member of the indie rock duo Minor Alps, alon ...
of Nada Surf
Nada Surf is a New York City-based American alternative rock band formed in the 1990s, consisting of Matthew Caws (guitar, vocals), Ira Elliot (drums), Doug Gillard (guitar, backing vocals), and Daniel Lorca (bass, backing vocals).
History ...
and his son made a PSA called "Living with a Mild Essential Tremor".
Research
Harmaline
Harmaline is a fluorescent indole alkaloid from the group of harmala alkaloids and beta-carbolines. It is the partly hydrogenated form of harmine.
Occurrence in nature
Various plants contain harmaline including ''Peganum harmala'' (Syrian rue) ...
is a widely used model of essential tremor (ET) in rodents. Harmaline is thought to act primarily on neurons in the inferior olive
The inferior olivary nucleus (ION), is a structure found in the medulla oblongata underneath the superior olivary nucleus.Gado, Thomas A. Woolsey; Joseph Hanaway; Mokhtar H. (2003). The brain atlas a visual guide to the human central nervous syste ...
. Olivocerebellar neurons exhibit rhythmic excitatory action when harmaline is applied locally.
Harmane
Harmane (harman) is a heterocyclic amine found in a variety of foods including coffee, sauces, and cooked meat. It is also present in tobacco smoke.
Chemistry
Harmane is a methylated derivative of β-carboline with the molecular formula C12H10N ...
or harmaline
Harmaline is a fluorescent indole alkaloid from the group of harmala alkaloids and beta-carbolines. It is the partly hydrogenated form of harmine.
Occurrence in nature
Various plants contain harmaline including ''Peganum harmala'' (Syrian rue) ...
has been implicated not only in essential tremors, but is also found in greater quantities in the brain fluid of people with Parkinson's disease
Parkinson's disease (PD), or simply Parkinson's, is a long-term degenerative disorder of the central nervous system that mainly affects the motor system. The symptoms usually emerge slowly, and as the disease worsens, non-motor symptoms beco ...
as well as cancer
Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. These contrast with benign tumors, which do not spread. Possible signs and symptoms include a lump, abnormal b ...
. Higher levels of the neurotoxin
Neurotoxins are toxins that are destructive to nerve tissue (causing neurotoxicity). Neurotoxins are an extensive class of exogenous chemical neurological insultsSpencer 2000 that can adversely affect function in both developing and mature ner ...
are associated with greater severity of the tremors. Harmane is particularly abundant in meats, and certain cooking practices (e.g., long cooking times) increase its concentration, however, at least one study has shown that harmane blood concentrations do not go up after meat consumption in ET patients with already elevated harmane levels, where as the control group's harmane levels increase accordingly, suggesting that another factor, like a metabolic defect, may be responsible for the higher harmane levels in E.T. patients.
Caprylic acid
Caprylic acid (), also known under the systematic name octanoic acid or C8 Acid, is a saturated fatty acid, medium-chain fatty acid (MCFA). It has the structural formula , and is a colorless oily liquid that is minimally soluble in water with a ...
is being researched as a possible treatment for essential tremor. It has currently been approved by the FDA and designated as GRAS, and is used as a food additive and has been studied as part of a ketogenic diet for treatment of epilepsy in children. Research on caprylic acid as a possible treatment for ET begun because researchers recognized that ethanol was effective in reducing tremor, and because of this, they looked into longer-chain alcohols reducing tremor. They discovered that 1-octanol reduced tremor and did not have the negative side effects of ethanol. Pharmacokinetic research on 1-octanol lead to the discovery that 1-octanol metabolized into caprylic acid in the body and that caprylic acid actually was the tremor-reducing agent. Many studies of the effects of caprylic acid on essential tremor have been done, including a dose-escalation study on ET patients and a study testing the effects of caprylic acid on central and peripheral tremor. The dose-escalation study examined doses of 8 mg/kg to 128 mg/kg and determined that these concentrations were safe with mild side effects. The maximum tolerated dose was not reached in this study. The study testing the effects of caprylic acid on central and peripheral tremors determined that caprylic acid reduced both.
Terminology
This type of tremor is often referred to as "kinetic tremor". Essential tremor has been known as "benign essential tremor", but the adjective "benign" has been removed in recognition of the sometimes disabling nature of the disorder.[
]
See also
* Intention tremor
Intention tremor is a dyskinetic disorder characterized by a broad, coarse, and low frequency (below 5 Hz) tremor evident during deliberate and visually-guided movement (hence the name intention tremor). An intention tremor is usually perpendi ...
References
External links
*
{{DEFAULTSORT:Essential Tremor
Extrapyramidal and movement disorders