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Tremor

A tremor is an involuntary,[1] 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, face, head, vocal folds, trunk, and legs. Most tremors occur in the hands. In some people, a tremor is a symptom of another neurological disorder.

For other uses, see Tremor (disambiguation).

Tremor

Neurology

tremor (also known as intention tremor) is a slow, broad tremor of the extremities that occurs at the end of a purposeful movement, such as trying to press a button or touching a finger to the tip of one's nose. In classic cerebellar tremor, a lesion on one side of the brain produces a tremor in that same side of the body that worsens with directed movement. Cerebellar damage can also produce a "wing-beating" type of tremor called rubral or Holmes' tremor — a combination of rest, action, and postural tremors. The tremor is often most prominent when the affected person is active or is maintaining a particular posture. Cerebellar tremor may be accompanied by other manifestations of ataxia, including dysarthria (speech problems), nystagmus (rapid, involuntary rolling of the eyes), gait problems and postural tremor of the trunk and neck. Titubation is tremor of the head, hands, and torso and is of cerebellar origin.

Cerebellar

tremor occurs in individuals of all ages who are affected by dystonia, a movement disorder in which sustained involuntary muscle contractions cause twisting and repetitive motions or painful and abnormal postures or positions. Dystonic tremor may affect any muscle in the body and is seen most often when the patient is in a certain position or moves a certain way. The pattern of dystonic tremor may differ from essential tremor. Dystonic tremors occur irregularly and can often be relieved by complete rest. Touching the affected body part or muscle may reduce tremor severity (a geste antagoniste). The tremor may be the initial sign of dystonia localized to a particular part of the body. The dystonic tremor has usually a frequency of about 7 Hz.[2]

Dystonic

(sometimes inaccurately called benign essential tremor) is the most common of the more than 20 types of tremor. Although the tremor may be mild and nonprogressive in some people, in others, the tremor is slowly progressive, starting on one side of the body but affecting both sides within 3 years. The hands are most often affected but the head, voice, tongue, legs, and trunk may also be involved. Head tremor may be seen as a vertical or horizontal motion. Essential tremor may be accompanied by mild gait disturbance. Tremor frequency may decrease as the person ages, but the severity may increase, affecting the person's ability to perform certain tasks or activities of daily living. Heightened emotion, stress, fever, physical exhaustion, or low blood sugar may trigger tremors or increase their severity. Onset is most common after age 40, although symptoms can appear at any age. It may occur in more than one family member. Children of a parent who has essential tremor have a 50 percent chance of inheriting the condition. Essential tremor is not associated with any known pathology. Its frequency is between 4 and 8 Hz.[2]

Essential tremor

tremor is characterized by fast (>12 Hz) rhythmic muscle contractions that occur in the legs and trunk immediately after standing up. Cramps are felt in the thighs and legs and the patient may shake uncontrollably when asked to stand in one spot. No other clinical signs or symptoms are present and the shaking ceases when the patient sits or is lifted off the ground. The high frequency of the tremor often makes the tremor look like rippling of leg muscles while standing. Orthostatic tremor may also occur in patients who have essential tremor, and there might be an overlap between these categories of tremor.

Orthostatic

tremor is caused by damage to structures within the brain that control movement. This resting tremor, which can occur as an isolated symptom or be seen in other disorders, is often a precursor to Parkinson's disease (more than 25 percent of patients with Parkinson's disease have an associated action tremor). A classic symptom is a characteristic fine tremor in the hands, which is traditionally described as a "pill-rolling" action of the hands,[3] but Parkinsonian tremor may also affect the arms, chin, lips, legs, and trunk, and can be markedly increased by stress or emotion. Onset is generally after age 60. Movement starts in one limb or on one side of the body and usually progresses to include the other side. The tremor's frequency is between 4 and 6 Hz.[2]

Parkinsonian

occurs in every normal individual and has no clinical significance. It is rarely visible and may be heightened by strong emotion (such as anxiety[4] or fear), physical exhaustion, hypoglycemia, hyperthyroidism, heavy metal poisoning, stimulants, alcohol withdrawal or fever. It can be seen in all voluntary muscle groups and can be detected by extending the arms and placing a piece of paper on top of the hands. Enhanced physiological tremor is a strengthening of physiological tremor to more visible levels. It is generally not caused by a neurological disease but by reaction to certain drugs, alcohol withdrawal, or medical conditions including an overactive thyroid and hypoglycemia. It is usually reversible once the cause is corrected. This tremor classically has a frequency of about 10 Hz.[5]

Physiological tremor

tremor (also called hysterical tremor and functional tremor) can occur at rest or during postural or kinetic movement. The characteristics of this kind of tremor may vary but generally include sudden onset and remission, increased incidence with stress, change in tremor direction or body part affected, and greatly decreased or disappearing tremor activity when the patient is distracted. Many patients with psychogenic tremor have a conversion disorder (see Post traumatic stress disorder) or another psychiatric disease.

Psychogenic

tremor is characterized by coarse slow tremor which is present at rest, at posture and with intention. This tremor is associated with conditions which affect the red nucleus in the midbrain, classically unusual strokes.

Rubral

Neuropathic tremor may occur in patients with , when the nerves that supply the body's muscles are traumatized by injury, disease, abnormality in the central nervous system, or as the result of systemic illnesses. It is most commonly observed in patients with an immunoglobulin M paraproteinaemic neuropathy (IgMNP), but also in patients with chronic inflammatory demyelinating polyneuropathy (CIDP). The tremor is predominantely exhibited as an action or postural tremor with a frequency of 3 to 10 Hz.[6] Peripheral neuropathy can affect the whole body or certain areas, such as the hands, and may be progressive. Resulting sensory loss may be seen as a tremor or ataxia (inability to coordinate voluntary muscle movement) of the affected limbs and problems with gait and balance. Clinical characteristics may be similar to those seen in patients with essential tremor.

peripheral neuropathies

is a self-induced tremor that is activated in humans. The mechanism is activated passive supine position, bringing the knees up and splitting them apart. The tremor is akin to the natural shaking mechanism in mammals to discharge stress and trauma.[7] The type of tremor is also known as "self-induced therapeutic tremor".[8] It is considered a kind of "spontaneous movement".[9]

Neurogenic tremor

Tremor is most commonly classified by clinical features and cause or origin. Some of the better-known forms of tremor, with their symptoms, include the following:


Tremor can result from other conditions as well

Causes[edit]

Tremor can be a symptom associated with disorders in those parts of the brain that control muscles throughout the body or in particular areas, such as the hands. Neurological disorders or conditions that can produce tremor include multiple sclerosis, stroke, traumatic brain injury, chronic kidney disease and a number of neurodegenerative diseases that damage or destroy parts of the brainstem or the cerebellum, Parkinson's disease being the one most often associated with tremor. Lesions of the Guillain-Mollaret triangle (also called myoclonic triangle or dentato-rubro-olivary pathway) impair the predictions performed by the cerebellum, causing repetitive muscle discharges by triggering oscillatory activity in the central nervous system.[10] Other causes include the use of drugs (such as amphetamines, cocaine, caffeine, corticosteroids, SSRIs) or alcohol, mercury poisoning, or the withdrawal of drugs such as alcohol or benzodiazepine. Tremors can also be seen in infants with phenylketonuria (PKU), overactive thyroid or liver failure. Tremors can be an indication of hypoglycemia, along with palpitations, sweating and anxiety. Tremor can also be caused by lack of sleep, lack of vitamins, or increased stress.[11][12] Deficiencies of magnesium and thiamine[13] have also been known to cause tremor or shaking, which resolves when the deficiency is corrected.[14] Tremors in animals can also be caused by some spider bites, e.g. the redback spider of Australia.[15]

: A fine tremor is very small or barely noticeable movement; a coarse tremor is a large movement. Tremors in between these two may be described as medium amplitude.

Amplitude

: A slow tremor makes a motion at a few times per second. A rapid or fast tremor is around 12 Hz or faster.[18][19] Tremors in between these two speeds may be described as intermediate speed.

Frequency

Affected body parts: For example, the left hand, or both legs, or the voice.

Parkinsonian tremor drug treatment involves or dopamine-like drugs such as pergolide, bromocriptine and ropinirole; They can be dangerous, however, as they may cause symptoms such as tardive dyskinesia, akathisia, clonus, and in rare instances tardive (late developing) psychosis. Other drugs used to lessen parkinsonian tremor include amantadine and anticholinergic drugs like benztropine

L-DOPA

Essential tremor may be treated with (such as propranolol and nadolol) or primidone, an anticonvulsant

beta blockers

Cerebellar tremor symptoms may decrease with the application of alcohol (ethanol) or benzodiazepine medications, both of which carry some risk of dependence or addiction

Rubral tremor patients may receive some relief using or anticholinergic drugs. Surgery may be helpful

L-DOPA

Dystonic tremor may respond to , anticholinergic drugs, and intramuscular injections of botulinum toxin. Botulinum toxin is also prescribed to treat voice and head tremors and several movement disorders

diazepam

Primary orthostatic tremor sometimes is treated with a combination of and primidone. Gabapentin provides relief in some cases

diazepam

Enhanced physiological tremor is usually reversible once the cause is corrected. If symptomatic treatment is needed, can be used

beta blockers

Cerebral Palsy

 ("at rest" muscle twitches; usually benign).

Fasciculation

Fibrillation

Restless Leg Syndrome

Shivering

Chronic solvent-induced encephalopathy

Neurology

. National Institute of Neurological Disorders and Stroke. July 20, 2007. Archived from the original on October 6, 2007. Retrieved 2007-10-08. Some text copied with permission and thanks.

"NINDS Tremor Information Page"

Sigvardt, Karen A.; Wheelock, Vicki L.; Kuznetsov, Alexey S.; Rubchinsky, Leonid L. (4 October 2007). . Scholarpedia. 2 (10): 1379. doi:10.4249/scholarpedia.1379.

"Leonid L. Rubchinsky et al. (2007) Tremor"

orthostatictremor.org