THE MERCK MANUAL-, Tremor in Ch. 91, Movement Disorders

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Tremor

Contributor: Eidelberg, MD

A tremor is an involuntary, rhythmic, shaking movement produced when muscles repeatedly contract and relax.

Everyone has a tremor to some degree. For example, when held outstretched, the hands usually tremble slightly in most people. Such slight, rapid tremor is normal and reflects the precise moment-by-moment control of muscles by nerves. In most people, the tremor is too slight to be noticed.

Factors that can make the tremor more noticeable include stress, anxiety, fatigue, alcohol withdrawal, an overactive thyroid gland (hyperthyroidism), consumption of caffeine, and use of drugs that are stimulants (such as ephedrine).

There are several types of abnormal tremor. Tremors are classified according to how fast the shaking movements are (frequency); how wide (amplitude) they are, ranging from fine to coarse; how often the tremors occur; how severe they are; and whether they occur during rest, during movement, or at the end of a purposeful movement.

Essential Tremor: This tremor is rapid and fine. Essential tremor usually begins in early adulthood but can begin at any age. The tremor slowly becomes more obvious and becomes more noticeable among older age groups. It was once called senile tremor because it is more common among people older than 60. Some forms of essential tremor run in families and are sometimes called familial tremor. The cause is unknown.

Usually, essential tremor remains mild and does not indicate serious disease; however, it can be troublesome and embarrassing. It can affect handwriting and make using utensils difficult.

Essential tremor usually affects the arms and, rarely, the legs. The tremor usually stops when the arms or legs are at rest but becomes obvious when the limbs are outstretched and worsens when the limbs are held in uncomfortable positions. Essential tremor usually affects both sides of the body but may affect one side more than the other. Sometimes the tremor affects the head, causing it to tremble and bob, and the vocal cords, causing the voice to shake. In some people, the tremor gradually worsens over time, eventually resulting in disability.

Resting Tremor: This slow, coarse tremor occurs when the muscles are at rest, making an arm or a leg shake even when a person is completely relaxed. Resting tremor may develop when collections of nerve cells at the base of the cerebrum (including the basal ganglia) are disturbed. Such disturbances may result from Parkinson's disease, use of certain drugs (such as lithium and antipsychotic drugs), or heavy metal poisoning (such as occurs in 's disease, in which copper accumulates in body tissues).

Resting tremor, although sometimes embarrassing, usually interferes little with voluntary movements, such as drinking a glass of water.

Intention (Cerebellar) Tremor: This relatively slow, broad tremor occurs at the end of a purposeful movement, such as trying to press a button. Intention tremor may result from a damage to the cerebellum or its connections. Multiple sclerosis and stroke are common causes. 's disease, alcoholism, and overuse of sedatives or anticonvulsants can cause the cerebellum to malfunction, resulting in intention tremor.

Intention tremor may increase during an activity, such as touching an object with the hand. The tremor may cause a person to miss the targeted object.

Flapping Tremor (Asterixis): This tremor is a coarse, slow, nonrhythmic movement that occurs when a person stretches out the arms and extends the hands. This tremor commonly results from liver failure and so has been called liver flap. However, it may also result from kidney failure and brain damage (encephalopathy) due to a metabolic disorder.

Muscle tone lapses suddenly and temporarily. As a result, the hand flaps; that is, it quickly drops, then returns to its original position. This tremor may be accompanied by other tremors and by myoclonus.

Diagnosis and Treatment

The development of a noticeable tremor should be evaluated by doctors. Doctors can usually identify the type of tremor by its characteristics. The type of tremor determines which procedures are performed. For essential tremor, doctors ask what drugs are being used and whether the person is experiencing anxiety or stress. Often, a blood test to detect an overactive thyroid gland is performed. For a resting tremor, a complete neurologic evaluation and other procedures to check for Parkinson's disease are performed. For intention tremor, an imaging procedure, such as computed tomography (CT) or magnetic resonance imaging (MRI), is often performed to look for damage to the brain. For flapping tremor, blood tests to evaluate liver and kidney function are performed.

Usually, treatment for a tremor is not needed. Avoiding uncomfortable positions can help. Objects should be grasped firmly but comfortably and held close to the body.

For people with essential tremor, drinking alcohol in moderation may reduce the tremor. However, heavy drinking or alcohol withdrawal can make the tremor worse. If people with essential tremor have difficulty using utensils or do work that requires steady hands, drugs may help. A beta-blocker, such as propranolol, is most commonly prescribed. If it does not help, primidone, an anticonvulsant, is often tried.

A resting tremor due to Parkinson's disease is treated as part of that disease. Intention tremors are difficult to treat, but if the condition affecting the cerebellum can be corrected, the tremor may resolve. For flapping tremor, the underlying liver or kidney disorder is treated. The tremor may resolve as liver or kidney function improves.

Brain surgery is performed only when an essential or a resting tremor is severe and disabling and drugs are ineffective. There are two types of surgery. In thalamotomy, parts of the thalamus (located at the base of the cerebrum, deep within the brain) are destroyed, and thus the pathways that produce the tremor are interrupted. In thalamic stimulation, an electrical probe is placed inside the thalamus. The probe delivers continuous high-frequency electrical stimulation to the thalamus, which generally reduces the tremor. Such procedures are available only at special centers.

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Dystonia

Contributor: Eidelberg, MD

Dystonia is involuntary, slow, repetitive, sustained muscle contractions that may cause freezing in the middle of an action, as well as twisting or turning of the trunk, the entire body, or part of the body.

Causes

Overactivity in several areas of the brain--the basal ganglia, thalamus, cerebellum, and cerebral cortex--seems to cause dystonia. Causes of dystonia include a severe lack of oxygen to the brain that occurs at birth or later in life, Parkinson's disease, multiple sclerosis, toxicity due to accumulation of certain metals (such as copper in 's disease), and stroke. Antipsychotic drugs can cause various types of dystonia, including involuntary shutting of the eyelids (blepharospasm), involuntary twisting of the neck (spasmodic torticollis), grimacing, and repetitive involuntary movements of the mouth and tongue (tardive dyskinesia). Chronic dystonia usually has a genetic cause.

Types and Symptoms of Dystonia

Idiopathic torsion dystonia refers to dystonia that has no known cause. Episodes begin between the ages of 6 and 12. Early symptoms can be mild or severe. Muscles contract slowly and abnormally, causing twisting and turning. The dystonia commonly starts in one foot or leg. It may remain limited to the trunk or a leg, but sometimes it affects the whole body, ultimately confining the child to a wheelchair. Another example of mild dystonia is persistent writer's cramp (however, not all writer's cramp is due to dystonia). When idiopathic torsion dystonia develops in adults, it usually begins in the face or arms and usually does not progress to other parts of the body.

Blepharospasm is a type of dystonia in which the eyelids are repeatedly and involuntarily forced shut. Occasionally, only one eye is affected at first, but ultimately, the other eye is also affected. It usually begins as excessive blinking, eye irritation, or extreme sensitivity to bright light. Many people with blepharospasm find ways to keep their eyes open, such as yawning, singing, or opening the mouth wide. These techniques become less effective as the disorder progresses. Blepharospasm can severely impair vision.

Spasmodic torticollis is dystonia involving the muscles of the neck.

Spasmodic dysphonia affects the muscles that control speech. People with this disorder usually have an essential tremor somewhere else as well. Spasms of the vocal cord muscles may block speech altogether or make speech sound strained, quavery, hoarse, whispery, jerky, creaky, staccato, or garbled and difficult to understand.

The yips are a type of dystonia experienced by some golfers who have muscle spasms. The muscles of the hands and wrists spontaneously contract, making putting nearly impossible. What is supposed to be a 3-foot putt can become a 15-foot putt when a golfer loses control because of the yips. Similarly, musicians who have bizarre spasms of the hands and arms that prevent them from performing may have dystonia.

Some dystonias are progressive; the movements may become more bizarre over time. Severe muscle contractions can force the neck and arms into odd, uncomfortable positions.

Treatment

Correcting or eliminating the cause of dystonia, if known, usually reduces the dystonia. For example, drugs used to treat Parkinson's disease may be effective for dystonia related to that disease. When dystonia is due to use of an antipsychotic drug, promptly taking diphenhydramine by injection or by mouth usually stops the episode quickly, and the antipsychotic is discontinued.

If the cause of dystonia is unknown, treatment is limited. Some people, especially children who have a hereditary form of dystonia (called dopa-responsive dystonia), improve dramatically when treated with levodopa. Benzodiazepines, a type of mild sedative, may be used. Baclofen, a muscle relaxant, may be given by mouth or by a pump implanted in the spinal canal. Anticholinergic drugs, such as trihexyphenidyl and diphenhydramine, are sometimes helpful, but they also cause side effects, such as drowsiness, dry mouth, blurred vision, dizziness, constipation, difficulty urinating, and tremor, especially in older people. The antipsychotics clozapine and olanzapine may be useful.

Injections of botulin (a bacterial toxin used to paralyze muscles) into the overactive muscles have been the most successful treatment. These injections are particularly useful for blepharospasm, spasmodic torticollis, and spasmodic dysphonia.

If drug treatment is ineffective and symptoms are severe, surgery may be performed. Procedures include pallidotomy (surgical destruction of a tiny area in one basal ganglion) and implantation of electrodes to stimulate the same area of the brain.

Physical therapy helps some people, especially those who are treated with botulin.

Spasmodic Torticollis

Spasmodic torticollis (cervical dystonia) is a disorder characterized by painful intermittent or continuous contractions or spasms of the neck muscles, forcing the head to rotate or tilt forward, backward, or sideways.

Spasmodic torticollis, a form of dystonia, is diagnosed in 3 of 10,000 people in the United States and is about 1½ times more common among women than among men. The disorder can occur at any age but usually develops between the ages of 25 and 55.

Usually, the cause is unknown. Dysfunction within the basal ganglia (collections of nerve cells located at the base of the cerebrum, deep within the brain) may be the cause. Sometimes spasmodic torticollis is caused by injury to the neck muscles during pregnancy or during a difficult delivery. This type of spasmodic torticollis is called congenital torticollis. Imbalanced eye muscles and bone or muscle deformities of the upper spine can cause torticollis in children.

Symptoms and Diagnosis

Initially, symptoms may be mild, but they may become severe. They include involuntary turning of the head, muscle pains, and slight tremor of the neck muscles. Usually, only one side of the neck is affected. The direction in which the head tilts and rotates depends on which neck muscles are affected. Sharp, painful neck muscle spasms may start suddenly and occur intermittently or continuously. The spasms occur without warning but rarely during sleep. One third of people who have this disorder also have spasms in other areas, usually in the eyelids, face, jaw, or hand.

To diagnose the disorder in children and adults, doctors ask detailed questions about past injuries and other neck problems. During a physical examination of a newborn, doctors can detect neck muscle damage that may cause congenital torticollis.

Imaging procedures, such as x-rays, computed tomography (CT), and magnetic resonance imaging (MRI), are sometimes used to look for specific causes of neck muscle spasms, although such causes are not commonly identified.

Treatment and Prognosis

When a cause, such as bone or muscle deformities, is identified, torticollis can usually be treated successfully. However, when the cause is unknown, treatment is less likely to control the spasms. Sometimes the spasm can be temporarily relieved by physical and occupational therapy, which may include biofeedback, electrical stimulation, massage, cold packs, heat, and deep heat with ultrasonography.

Certain drugs help reduce muscle spasms and involuntary movements in about one third of adults with spasmodic torticollis. Usually, these drugs also help control pain due to the spasms. Commonly used are anticholinergic drugs (such as trihexyphenidyl and benztropine), which block specific nerve impulses, and benzodiazepines (particularly clonazepam), which are mild sedatives. Less frequently, muscle relaxants (such as baclofen) and antidepressants (such as amitriptyline) are used.

For people with significant pain and an abnormal posture, several injections of botulin (a bacterial toxin used to paralyze muscles), given in a low dose, is the best treatment. This toxin blocks muscle contractions. For most people, botulin injections reduce pain and spasms, so that the head can be held more normally. Improvement may last for a few months; then the treatment may be repeated as needed. Surgically removing the nerves to the dysfunctional neck muscles (called selective denervation) is sometimes successful and may be tried if other treatments do not provide relief. If emotional problems contribute to the spasms, psychiatric treatment may help.

For torticollis in newborns, intensive physical therapy to stretch the damaged muscle is begun within the first few months of life. If the physical therapy is unsuccessful or started too late, the muscle may have to be repaired surgically.

About 10 to 20% of people who have spasmodic torticollis--usually people younger than 40 with mild cases--recover without treatment within 5 years. However, in most adults, the disorder gradually worsens for 1 to 5 years, then stabilizes. Torticollis may persist for life, producing continued pain, restricted movement of the neck, and an abnormal posture.

Overview of Dyskinesias (Paroxysmal) ( This is the oine I have,,,,but I also have it in my voice box, and get the electrical jolts down my right leg at times. I call this diversiving.as in why just have one when there so many illness's out there we can add to liver disease. : )) Joanne

Paroxysmal dyskinesias are neurologic conditions characterized by sudden episodes of abnormal involuntary movements (hyperkinesias). These may include any combination of involuntary, rapid, randomly irregular jerky movements (chorea); relatively slow, writhing motions that appear to flow into one another (athetosis); increased muscle tone with repetitive, twisting, patterned movements and distorted posturing (dystonia); and uncontrollable flinging movements of an arm, a leg, or both (ballismus). The term paroxysmal indicates that the abnormal movements are sudden and unpredictable, with a relatively rapid return to normal motor function and behavior.

Paroxysmal dyskinesias are often classified into paroxysmal kinesigenic dyskinesia (PKD) and paroxysmal non-kinesigenic dyskinesia (PNKD), based upon precipitating factors that precede or trigger the episodes of abnormal, involuntary movement. In patients with PKD the episodes of hyperkinetic movements are provoked by sudden voluntary movement or unexpected stimuli (startle). In contrast, in those with non-kinesigenic dyskinesia, the attacks may occur spontaneously while at rest or out of a background of normal motor activity, but may be exacerbated by alcohol or caffeine consumption, stress, fatigue, or other factors. Other types of paroxysmal dyskinesias include episodes precipitated by prolonged exertion (paroxysmal exertion-induced dyskinesia) or sleep (paroxysmal hypnogenic dyskinesia).

Paroxysmal dyskinesias may also be further categorized according to the duration of the attacks. They may be described as "short-lasting" if episodes are less than or equal to 5 minutes or "long-lasting" if attacks are longer than 5 minutes. The paroxysmal dyskinesias may be familial, appear to occur randomly for unknown reasons (sporadically), or occur secondary to other underlying conditions (symptomatic).

WE MOVEE-mail: wemove@...wemove.org • mdvu.org

Clinical Features and Classification

The primary finding associated with paroxysmal dyskinesia is sudden, transient attacks of chorea, athetosis, dystonia, ballismus, or any combination of these abnormal movements involving muscle groups of the arms, legs, trunk, face, and/or neck. These episodes may be relatively short- or long-lasting in duration and occur spontaneously or be brought on by sudden voluntary movement, stress, fatigue, caffeine, alcohol, heat, cold, prolonged exertion, sleep, or other factors. Following is a more in-depth description of these paroxysmal movement disorders, including some rare disease variants that have been described in the medical literature.

Paroxysmal kinesigenic dyskinesia (PKD)Previously designated as "paroxysmal kinesigenic choreoathetosis" (PKC), the term "paroxysmal kinesigenic dyskinesia" is now considered more appropriate since the episodes are often not witnessed and therefore the movement disorder cannot be classified into choreic, athetotic, ballistic, or dystonic. In many patients with PKD, particularly those with idiopathic (i.e., familial or sporadic) disease, symptom onset is before age 20, usually during childhood. However, the age at onset may vary, ranging from about 6 months to 40 years in familial cases, but the age at onset may be considerably later in secondary (symptomatic) cases. While many reports have concluded that males are affected more frequently than females by idiopathic (familial and sporadic) PKD, a recent report that primarily included idiopathic sporadic and secondary cases indicated that males and females appear to be affected relatively equally.

The transient attacks associated with PKD primarily affect muscles of the arms and legs; however, muscles of the face, neck, and/or trunk may also be involved. PKD episodes may affect muscle groups on one (unilateral) or both sides (bilateral) of the body, but even if bilateral they are usually asymmetrical. Involvement of facial or oromandibular muscles often results in transient facial grimacing, difficulties speaking (dysarthria), or even muteness; however, the episodes are not accompanied by altered consciousness. When leg and trunk muscles are affected, falls may occur, causing a risk of injury. PKD may interfere with walking or standing or conducting other activities of daily living (ADLs), potentially resulting in severe disability.

In addition to sudden movement, some episodes may also be provoked by unexpected stimuli (startle), yawning, talking, hyperventilation, the anticipation of movement, or light (photic) stimulation. Attacks may be worsened by certain factors, such as stress, cold, heat, or menstruation.

Most patients with PKD experience daily episodes. The frequency of attacks ranges from as few as 1 each month (or less) to as many as 100 each day. Before the onset of such episodes, some patients may experience unusual warning or "premonitory" sensations, such as prickling, tingling, or crawling (paresthesias); dizziness; or muscle tension. Such abnormal sensations usually involve the affected region. The frequency of PKD episodes usually decreases with age.

Generally, most patients with PKD have brief attacks lasting from seconds up to 5 minutes. However, some rare cases have been reported in which kinesigenic episodes may have a duration of more than 5 minutes up to hours. According to some reports, long-lasting PKD appears to be associated with an older age at symptom onset than that seen with short-lasting PKD; in addition, short-lasting episodes seem to occur more frequently than long-lasting attacks. It is also important to note that, in some patients with PKD, the length of attacks may change over time from short- to long-lasting or vice versa.

Paroxysmal non-kinesigenic dyskinesia (PNKD)In many individuals with paroxysmal non-kinesigenic dyskinesia (PNKD), symptoms become apparent before age 20. However, the age at onset may be extremely variable and the symptoms may not become manifested until 40 years of age or even later. Males appear to be more frequently affected by PNKD than females, but some series have not found a male preponderance.

Phenomenologically, PNKD is similar to PKD, except for the precipitating factors. This paroxysmal movement disorder was previously categorized as "paroxysmal dystonic choreoathetosis" (PDC). However, the term "paroxysmal non-kinesigenic dyskinesia" has since been recommended to more appropriately imply the larger spectrum of hyperkinetic movements potentially associated with the disease. As with PKD, PNKD attacks may be associated with any combination of various movement abnormalities, including chorea, athetosis, dystonic posturing, and ballismus. It is again important to emphasize that the episodes are not accompanied by an altered state of consciousness. Attacks may be so severe that they result in sudden falls or significantly interfere with walking, standing, or performing other activities of daily living (ADLs), potentially resulting in severe disability.

PNKD episodes may occur spontaneously without any specific "triggering" factors. However, episodes may be worsened by stress, anxiety, or excitement; fatigue; heat or cold; consumption of alcohol; intake of caffeine, such as in coffee, tea, or chocolate; fasting; or other factors.

The frequency of PNKD episodes is typically lower than that associated with PKD, ranging from approximately 2 to 3 per month up to about 20 per day; most patients with PKD experience daily attacks (up to 100 per day). In some patients, unusual "foreboding" sensations may occur prior to PNKD episodes. These may include prickling, crawling, or tingling sensations (parenthesis) or muscle tension in the affected region. As with PKD, PNKD attacks tend to decrease with age.

In contrast to usually brief episodes of PKD, the PNKD attacks last longer (from approximately 5 minutes up to about 4 hours or, sometimes, up to 2 days), although cases of PNKD have been reported in which non-kinesigenic episodes have a short-lasting duration of about 10 to 30 seconds (less than 5 minutes) . Thus, similar to PKD, PNKD is further classified based upon the duration of episodes into "short-lasting" (less than or equal to 5 minutes) or "long-lasting" (longer than 5 minutes). As with PKD, there have also been reports in which some patients with PNKD have experienced a change in the length of episodes from long- to short-lasting or vice versa. In addition, long-lasting PNKD appears to be associated with a younger age at symptom onset than that seen with short-lasting PNKD.

Paroxysmal exertion-induced dyskinesia (PED)A relatively rare form of paroxysmal dyskinesia has been described in which episodes are induced by prolonged exertion. Previously categorized as "intermediate PNKD," this variant is currently classified as "paroxysmal exertion-induced dyskinesia" (PED) specifically based upon the precipitant rather than the duration of the attacks.

In patients with idiopathic (familial or sporadic) PED, symptoms typically become apparent during childhood. In the only recorded case of secondary (symptomatic) PED, the age at onset was 29 years. In those with familial PED, females appear to be affected more frequently than males. However, in idiopathic sporadic PED, females and males are affected relatively equally.

PED is primarily characterized by sudden, transient, dystonic attacks, associated with involuntary, repetitive, twisting motions and distorted, often painful posturing. In some patients, attacks of dystonia may be accompanied by irregular jerky movements (chorea) and relatively slow, writhing movements that appear to flow into one another (athetosis). Such episodes are brought on by strenuous activity or prolonged exertion, such as running or walking for approximately 5 to 15 minutes. A few cases have also been reported in which PED attacks are provoked by passive movements of affected limbs. Episodes may be worsened by certain factors, including stress, cold, or menstruation. PED attacks primarily involve the legs or feet. However, muscles of the arms, face, neck, and/or trunk may sometimes be involved in those with short-lasting PED episodes (see below). Although muscle groups are often affected on both sides of the body (bilateral), only one side (unilateral) may be involved in some patients. Unlike PKD and PNKD, patients with PED usually do not experience any premonitory sensations prior to the onset of PED attacks.

Most patients with PED have about 1 to 5 episodes per month. However, some may experience up to 1 to 2 attacks daily. PED episodes usually have a duration ranging from about 5 to 30 minutes. Yet a few cases have been reported in which episodes were short-lasting, with a duration of seconds up to 2 minutes. In addition, in one family originally classified as having PNKD who had episodes precipitated by prolonged exertion, some affected members experienced both short- and long-lasting attacks: episodes lasted for a few seconds up to about a minute or as long as up to 2 days. Reports suggest that long-lasting PED episodes appear to be more common in younger individuals.

Paroxysmal hypnogenic dyskinesia (PHD)Paroxysmal hypnogenic dyskinesia or PHD, a rare disease variant, is characterized by transient attacks of involuntary movements occurring during non-REM (NREM or non-rapid eye movement) sleep. In rare instances, PHD episodes may be preceded by premonitory, potentially painful sensations. In addition, the attacks are often preceded by signs of awakening (arousal). During PHD attacks, the eyes may open and there may be abnormal, involuntary, potentially violent movements of the arms, legs, and trunk. These may include uncontrollable flinging or throwing movements of the arms and legs (ballismus); excessive rigidity, with associated, repetitive, twisting motions and distorted, potentially painful posturing (dystonia); and irregular jerky motions (chorea) and relatively slow, writhing movements that appear to merge into one another (athetosis). In some instances, the attacks may be associated with additional findings, including involuntary utterances (vocalizations), irregular breathing patterns, or an accelerated heart rate (tachycardia). Although patients usually fall asleep after PHD episodes, they typically remember the attacks. Episodes may be worsened by certain factors, such as fatigue, stress, increased activity, or menstruation.

Idiopathic (familial or sporadic) PHD usually becomes apparent during childhood. Reports suggest that familial PHD typically has a younger age at symptom onset than sporadic disease. Based upon various reports, the age at onset may range from about 2 to 23 years in familial cases and approximately 3 to 47 years in idiopathic sporadic cases.

In some patients, PHD attacks may initially occur approximately 4 to 5 times each year. Over time, however, the frequency of episodes may increase up to 4 to 5 times nightly. The attacks are usually relatively brief, ranging from about 20 to 50 seconds or up to approximately 2 minutes. However, in some patients, episodes may have a longer duration of more than 5 minutes up to about 50 minutes.

In some instances, patients may experience nocturnal episodes as well as daytime kinesigenic or non-kinesigenic attacks. In addition, in some affected families (kindreds), different members may have different forms of paroxysmal dyskinesia.