Chapter 9: Tremor and Other Involuntary Movements

Neeraj Kumar, MD; Andrew C. Greenlund, MD, PhD

I. CASE HISTORIES

Case 9-1. A 65-year-old man is evaluated for hand tremors. He recalls that his hands would occasionally shake in his teenage years. The tremors have worsened over the past year and interfere with activities such as eating and dressing. He has noted that alcohol reduces the tremors. His mother had a history of head tremor, and a maternal uncle had hand tremors. The only abnormality on his examination is the presence of tremors of the outstretched hands.

1. What type of tremor is this?
2. What are the likely etiologies?
3. What measures might be taken to help him?

Case 9-2. A 67-year-old man is evaluated for right-hand tremors. Two years ago his wife noted that his right hand would shake when he was watching television. The tremor did not interfere with his activities. For the same duration he has noted that he takes a greater time to do his day-to-day activities. His wife reports that he tends to shuffle while walking and does not swing his right arm as much as the left. His children feel that he looks depressed. His neurologic examination is remarkable for reduced facial expression, decreased blink frequency, and a soft voice. He has cogwheel rigidity involving the upper limbs, right greater than left. Rapid alternating movements involving the right hand and foot are reduced. He has a resting tremor of the right hand, which increases when he walks. His gait has a narrow base with a reduced arm swing on the right. He takes multiple steps to execute a turn. On being pulled backwards he has difficulty maintaining his posture.

1. What type of tremor is this?
2. What is the likely diagnosis?
3. Can this diagnosis be made in the absence of tremors?

II. DISORDERS

In general, movement disorders can be categorized into those with an excess of movements or those with a paucity of movements. The former are called hyperkinetic movement disorders. The terms hyperkinesia (excessive movements) and dyskinesia (unnatural movements) are interchangeable. The major categories of hyperkinetic movement disorders are tremor, chorea, dystonia, myoclonus, and tic. The prototypic hypokinetic (decreased) movement disorder is Parkinson disease.

Table 9-1 Common Etiologies for Movement Disorders

Tremors

Tremor is the most commonly encountered movement disorder. The hallmark feature of tremor is a rhythmic (repetitive) movement that has a constant periodicity. The amplitude of tremor determines the degree of disability. The hands are most frequently affected, and categorization is aided by assessing whether the tremor is present at rest, during voluntary sustained postures, or with action. Based on this, the three commonest types of tremors are rest tremor, action-postural tremor, and terminal tremor (intention tremor, dysmetria, ataxia).

Rest tremor (Video 9-1) is the tremor seen in Parkinson disease and other extrapyramidal disorders and occurs when the affected body part is supported against gravity and is not actively contracting. A rest tremor decreases with activity. Tremor of a hand at one's side while walking or of a leg while seated (foot resting on the floor) is a typical parkinsonian rest tremor.

Action-postural tremor is typically absent at rest but manifest when the body part is activated. When the hand is affected this may interfere with activities such as writing, drinking, or eating. Essential tremor (Video 9-2) is the most common tremor disorder and typically presents as an action-postural tremor. It involves hands most frequently (typically bilateral), but also the head, as well as voice head and voice tremor are not seen in Parkinson disease. The age of onset may range from early teenage years to late life. A family history of tremors is common in essential tremor, often with an autosomal dominant pattern of inheritance. In many patients the tremor decreases with alcohol consumption. Drugs such as valproic acid, lithium, and theophylline derivatives or metabolic disorders such as pulmonary or hepatic failure may also induce action-postural tremors. Tremors that occur during a specific task are called task-specific tremors. The best example in this category is primary writing tremor that exclusively affects handwriting.

Tremor of the hands that increases in amplitude as the hand reaches the target is termed terminal or intention tremor. This is typical of the ataxia of cerebellar disease. Action tremor is distinguished from terminal tremor (ataxia) by the ability to hit the target on finger-to-nose testing. Terminal tremor is characterized by inability to hit the target. 

Chorea

Chorea is characterized by rapidly flowing movements that are neither sustained nor stereotyped. When affecting a limb, they give the appearance of a randomly moving dance. Choreiform disorders reflect basal ganglia dysfunction. Huntington disease (Video 9-3) is an example of a condition marked by chorea; it is an autosomal dominant disorder that also includes dementia and personality change. Probably the most common cause of chorea (dyskinesia) is levodopa treatment of Parkinson disease (which resolves with dose reduction). Other causes of chorea include hyperthyroidism, lupus erythematosus, high-estrogen states (including pregnancy and oral estrogens), rheumatic fever (Sydenham chorea), and occasionally tardive syndromes due to chronic dopamine antagonist therapy (neuroleptics and antiemetics). Drugs that reduce brain dopamine activity are used to treat chorea.

Dystonia

Dystonia (Video 9-4) is characterized by sustained involuntary muscle contraction of a body part, resulting in twisting or otherwise abnormal postures. Superimposed on these tonic deviations of limb or trunk are often stereotyped repetitive movements. A hallmark feature of dystonia is sustained co-contraction of agonist and antagonist muscles. Dystonic movements are usually more evident during the execution of voluntary movements. In advanced cases the dystonia may progress to produce posturing at rest. Dystonias occurring in adulthood usually affect only one limited region of the body, usually the upper body. Cervical dystonia or spasmodic torticollis is one example, and others include blepharospasm (eye closure dystonia), oromandibular dystonia, and laryngeal dystonia (spasmodic dysphonia). Many upper limb dystonias are action dystonias and are precipitated by a specific task such as writing (writer's cramp), typing, or playing a musical instrument. Dystonia can also be seen in a variety of metabolic disorders such as Wilson disease and degenerative disorders such as Parkinson disease. Drug-induced dystonia can occur after therapy with dopamine receptor blocking agents such as haloperidol. One manifestation of this can be oculogyric crisis in which tonic ocular deviation occurs, usually upward gaze. Botulinum toxin therapy has revolutionized the management of focal dystonia.

Myoclonus

Myoclonus (Video 9-5) is defined as a sudden, brief, shocklike, involuntary movement. Myoclonus occurs normally in many individuals as a feature of sleep onset (sleep starts, hypnic jerks), may occur without an underlying cause (essential), or infrequently occurs in various forms of epilepsy. New myoclonic movements presenting in adulthood are best viewed as a symptom or sign and should prompt search for an underlying cause. Myoclonus may be present at rest (spontaneous), with voluntary movement (action myoclonus), or be induced by various stimuli (reflex myoclonus). Hypoxic-ischemic injury can result in disabling action myoclonus, and the presence of myoclonus after hypoxic-ischemic injury is a poor prognostic sign. Myoclonus is a well-recognized feature of Creutzfeldt-Jakob disease. It may also occur with certain drug therapies, such as narcotics or selective serotonin reuptake inhibitors. Along with asterixis, it is a feature of toxic-metabolic encephalopathies. A search for and, if possible, treatment of the underlying cause are important.

Tics

Motor tics (Video 9-6) are brief, rapid, nonrhythmic, stereotypic behaviors that vary in intensity and are repeated at irregular intervals. Vocal tics refer to sounds made through the nose, mouth, or throat. Tics are stereotyped movements that usually occur in response to an irresistible urge. They can be suppressed for variable periods of time, but when suppressed, inner tension builds up and only is relieved by an increased burst of more tics. Tics may be very simple movements such as a shoulder shrug, head jerks, or blinking, in which case they may resemble other types of movement disorders, or if infrequent, may pass for normal. However, tics may include more complex movements unlike any of the other categories of dyskinesias, such as head shaking or other repetitive stereotyped movements, kicking, hitting, or bizarre leg movements when walking. Vocal tics range from simple throat clearing, sniffing, hissing, grunting, or coughing to saying or shouting words or phrases, including coprolalia. The combination of simple and complex motor and vocal tics is the characteristic of Tourette syndrome, a diagnosis made if the onset is in childhood or adolescence. Tourette syndrome has a relapsing and remitting course, and has been associated with attention deficit and obsessive-compulsive disorders.   

III. HISTORY

Table 9-2 Important Historical Points

IV. EXAMINATION

Usually the nature of the movement disorder is evident by observation. However, a comprehensive history and examination should be performed since it is crucial to determine the overall context in which the movement occurs. Clinical signs accompanying the specific type of movement disorder aids in a more specific diagnosis. Close attention should be paid to the temporal profile, distribution, precipitating or relieving factors, associated neurologic symptoms and signs, and medical history. A detailed family history should be taken in all cases. Many movement disorders are caused by current or prior exposure to drugs.

Tremor

Bedside observations allow classification of tremors into one of three categories (rest, action-postural, terminal). Patients with resting tremor are often more bothered by embarrassment than disability. If the resting tremor is due to Parkinson disease, it may be associated with masked facies, rigidity, reduced arm swing, and shuffling gait. The bradykinesia (slowness) and postural instability are often a source of disability. Before diagnosing a rest tremor the examiner must ensure that the patient is relaxed and the limb is placed in a fully supported position. The classic appearance consists of pronation-supination of the forearm or a "pill-rolling" movement of the thumb and fingers. In general, parkinsonian rest tremors oscillate between 4 Hz and 6 Hz. Patients may sit on their hands to conceal the tremor. Since the tremor decreases with activity it may not interfere with various tasks. An action or even the thought of action may cause the tremor to disappear. In most cases the tremor starts asymmetrically and may initially be evident only when the patients walks with hands down at the side or when the patient does rapid movements with the contralateral limb.

Mild action-postural tremors are mainly a source of embarrassment. As they become more severe, they interfere significantly with daily activities such as eating, drinking, and shaving. An action-postural tremor is best observed with the arms held outstretched in a sustained posture. Placing the fingers in front of the nose may augment an action-postural tremor. Action-postural tremors may involve the legs, head, or voice. They are evident with limb movement, and the same magnitude of movement is present throughout the range of movement. Writing or drawing a spiral allows observation and recording of action-postural tremors. In essential tremor, no other neurologic abnormalities are found.

The hallmark of a terminal tremor is exacerbation with action, particularly in the terminal part of a movement; this is usually tested with finger-to-nose pointing. An increase in amplitude in the terminal part of the movement usually indicates cerebellar dysfunction. The tremor of Wilson disease can be of any type. It may be accompanied by dysarthria, dystonia, or other neuropsychiatric manifestations.

Chorea

Patients can conceal choreiform movements by incorporating them into semipurposeful movements. Chorea may be accompanied by an inability to maintain a sustained muscle contraction. The associated symptoms may include clumsiness or frequently dropping objects. Clinically this can be detected by the patient's inability to maintain the fist in a tight grip ("milkmaid grip") or inability to keep the tongue protruded ("darting tongue").

Dystonia

Age of onset, distribution of dystonia, manner of progression, and associated neurologic signs and symptoms are all important in the evaluation of dystonia. Primary dystonia is characterized by the absence of other neurologic abnormalities. The presence of additional neurologic signs and symptoms should prompt a search for a secondary form of dystonia. "Sensory tricks," such as touching or holding the affected body part, can suppress some dystonias such as torticollis. Variability of symptoms, diurnal variations, and sensory tricks can be seen in dystonias and should not suggest a secondary cause.

Myoclonus

Asterixis is a form of myoclonus (negative myoclonus) in which a brief flap of the outstretched limbs occurs due to transient inhibition of the muscles responsible for maintaining posture. It is seen as a momentary and repetitive partial flexion of the wrists during attempted sustained wrist extension. It can be seen in various metabolic encephalopathies. Also important to recognize is myoclonus involving the hands that may occur, continuously mimicking a tremor. Close observation indicates an irregular series of very rapid muscle twitches.

Tics

Patients with tics may be able to suppress the tic while in the medical office. Discrete observation may make the tic disorder more evident.

V. CLUES TO DIAGNOSIS

The diagnosis of involuntary movements is made clinically. The hallmark of tremors is their rhythmic and repetitive nature. The movements in chorea are random and unpredictable. Dystonic movements are more stereotyped and patterned than choreiform movements and not as quick as myoclonic movements. Myoclonus is characterized by brief and shocklike movements. Tics are distinguished by their complexity, suppressibility, and associated urge, which is relieved when the movement is performed. A quick, simple tic can be difficult to differentiate from myoclonus or chorea. Rarely tics can be associated with sustained twisting movements, in which case they are considered dystonic or tonic tics. 

A family history or exposure to a drug or toxin may provide a clue to the underlying cause of a movement disorder. At times a toxicology screen may be indicated. Hyperthyroidism should be ruled out as a cause of the movements. A serum ceruloplasmin estimation and slit-lamp examination are indicated to rule out Wilson disease in young individuals with any involuntary movement of unknown cause. A brain magnetic resonance imaging (MRI) may be indicated to rule out structural disease in involuntary movements of uncertain etiology. When an underlying cause of myoclonus is suspected, then commonly performed investigations may include electrolytes, glucose, renal and hepatic function studies, drug and toxin screen, brain MRI, and electroencephalogram. Antistreptolysin O titers and workup for lupus erythematosus may be obtained in the workup of chorea. When the history and examination suggest a primary tic disorder, extensive investigations are typically not required.

VI. RED FLAGS AND WHEN TO REFER

Tremors

In general, essential tremor as a cause of action-postural tremor and Parkinson disease as a cause of rest tremor are easy to diagnose, and the appropriate treatment or referral to neurology can be initiated. The presence of the following features in association with rest tremors may suggest an alternative extrapyramidal disorder: early dementia, prominent and early falls, evidence of significant autonomic dysfunction, and restricted vertical eye movements. Patients with new terminal (intention, ataxia) tremor probably need imaging and referral to neurology to evaluate the source of cerebellar dysfunction.

Chorea, Dystonia, Myoclonus, Tics

Other hyperkinetic disorders such as chorea, dystonia, and myoclonus are often seen by neurologists. The onset of chorea in an older person should prompt the consideration of Huntington disease. Adult-onset dystonias are generally associated with onset in the arm, neck, or face. Generalized dystonia in adults often requires an extensive routine evaluation for an underlying disorder by a neurologist. The presence of seizures or additional neurologic signs and symptoms suggests the possibility of epileptic or symptomatic myoclonus and requires more immediate further evaluation. The diagnosis of Tourette syndrome may be delayed for years, and the symptoms may be mistakenly attributed to psychiatric illness.

Table 9-3 Time Frame for Evaluation and Referral

VII. CASE DISCUSSIONS

Case 9-1. The patient started having tremors in his teenage years. The course appears to be slowly progressive. For the past year the tremors have been interfering with his activities. The only abnormality on his examination is the presence of tremors of the outstretched hands. He has an action-postural tremor, most likely due to essential tremor. The decrease in tremor severity with alcohol and family history suggestive of autosomal dominant transmission further substantiate this diagnosis. Medications such as propranolol or primidone are commonly used first-line agents.

Case 9-2. The clinical presentation of this patient is typical of Parkinson disease. Rest tremor is a cardinal symptom of Parkinson disease. Tremors may not be seen in up to a third of patients with Parkinson disease. In most cases, the tremor starts asymmetrically. With distraction, the tremor may increase. The tremor disappears with activity. The patient also has the other typical features of Parkinson disease, namely, bradykinesia, rigidity, and postural instability. Referral to a neurologist for initiation of dopaminergic agents or symptomatic treatment would be indicated. Very severely affected individuals who have responded to medications in the past could be considered for surgical treatment in multidisciplinary centers.

VIII. CME QUESTIONS

1. A 24-year-old man presents with symptoms and examination findings suggestive of essential tremor. Which of the following statements is true?

a. A positive family history means that Wilson disease or Huntington disease is likely.
b. Essential tremor should never cause problems with his head or voice.
c. He should be informed that his tremor may worsen and affect daily activities.
d. If the tremor is suppressed by alcohol, it is likely to be related to cerebellar disease.

2. Common early features of Parkinson disease include which of the following:

a. Autonomic symptoms, intention tremor, and inability to perform tandem gait
b. Bradykinesia and dementia that precede the reported onset of motor symptoms
c. Choreiform movements, depression, and personality changes
d. Rest tremor, postural instability, and micrographia

3. The best example of an adult-onset focal dystonia is:

a. Essential myoclonus
b. Huntington chorea
c. Spasmodic torticollis
d. Tourette syndrome

4. All the following are examples of adult-onset focal dystonia except:

a. Blepharospasm
b. Spasmodic torticollis
c. Tourette syndrome
d. Writer's cramp

5. A 24-year-old man presents with a six-month history of a constant, fine fast-action tremor of his hands. He is on lithium for bipolar disorder and has a brother who is bedridden from an unknown disease. All of the following etiologies are possible except:

a. Benign essential action tremor
b, Lithium-induced tremor
c. Tic disorder
d. Wilson disease

CME ANSWERS

1. c. He should be informed that his tremor may worsen and affect daily activities.

2. d. Rest tremor, postural instability, and micrographia

3. c. Spasmodic torticollis

4. c. Tourette syndrome

5. c. Tic disorder