Movement Disorders




Involuntary movements are usually associated with abnormalities of the basal ganglia and their connections and occur in several different neurological disorders. Abnormal movements can be the main or initial features of disease, or they can occur as a late manifestation. Discussion of the former type is in this chapter, and the latter in other chapters.


Approach to the Patient


Movement disorders are difficult to describe; they require visualization. If abnormal movements are not present at the time of examination, instruct the parents to videotape the movements at home. Some relatively common movements are recognizable by description, but the rich variety of abnormal movements and postures that may occur defies classification. The most experienced observer will mistake, at times, one movement for another or will have difficulty conceptualizing the nature of an abnormal movement.


Many abnormal movements are paroxysmal or at least intermittent. Motion, excitement, startle, emotional upset, or sleep induces some movements. The physician should ask what makes the movement worse and if it is action-induced. Ask children to perform the action during the examination. Paroxysmal movements raise the question of epilepsy. Indeed, the concurrent presence of seizures and involuntary movements characterize many neurological disorders of childhood. Nocturnal paroxysmal dystonia , once thought a movement disorder, is actually frontal lobe epilepsy (see Chapter 1 ). The clinical and conceptual distinction between spinal myoclonus and myoclonic seizures can be difficult. The following guidelines are useful to distinguish involuntary movements from seizures: (1) involuntary movements, with the exception of spinal myoclonus and periodic movements of sleep, abate or disappear during sleep and seizures persist or may worsen; (2) involuntary movements usually have a more stereotyped appearance and, with the exception of acute drug reactions, are more persistent than seizures; (3) loss of consciousness or awareness is characteristic of seizures but not involuntary movements; and (4) epileptiform activity on electroencephalography (EEG) accompanies seizures, but not involuntary movements.


Involuntary contractions of a muscle that do not move a joint may be fasciculations, focal seizures, or myoclonus. Low-amplitude jerking movements that move a joint or muscles may be focal seizures, chorea, myoclonus, tics, or hemifacial spasm. High-amplitude jerking movements that move a limb or limbs may be seizures, ballismus, or myoclonus. Slow, writhing movements and abnormal posturing may be due to athetosis, dystonia, continuous motor unit activity (see Chapter 8 ), or seizures. The possible causes of rhythmic movements may be tremor, seizures, or myoclonus.




Chorea and Athetosis


Chorea is a rapid movement affecting any part of the body that the patient often incorporates into a voluntary movement in an attempt to hide it. The movements are random but neither rhythmic nor stereotyped, and they migrate from side-to-side and limb-to-limb. Because the involuntary movement flows into a voluntary movement, it gives the appearance of constant movement (restlessness). Akathisia , an inward compulsion to move (discussed later) also causes the appearance of restlessness. Depending on the condition, chorea may be unilateral or bilateral and may affect the face and trunk as well as the limbs. An observer cannot precisely describe chorea because it has no fixed form.


Chorea is more readily observed when separated from the superimposed voluntary movement that follows. Ask the child to raise both hands upward beside the head with the palms facing each other. Low-amplitude jerking movements occur, which turns the arm into pronation. When the child lightly grips the examiner’s fingers, the grip alternately tightens and loosens, as if the patient is “milking” the examiner’s hands. Hypotonia is common in many conditions causing chorea. Tendon reflexes may be normoreactive, but, at times, a choreic movement occurs during the patellar response, producing an extra kick. Children move their tongue constantly, in and out, when asked to maintain it protruded (motor impersistence).


Athetosis is a low-amplitude chorea. It is low-amplitude, writhing movements of the limbs that may occur alone but is often associated with chorea (choreoathetosis). The usual cause of athetosis without chorea is perinatal brain injury. Kernicterus was once a major cause of choreathetosis but is now a rare event. Perinatal asphyxia is now the predominant etiology. Many children with athetosis have atonic cerebral palsy, and others have spastic diplegia.


Ballismus is a high-amplitude chorea. It is a high-amplitude, violent flinging of a limb from the shoulder or pelvis. In adults, it may occur in limbs contralateral to a vascular lesion in the subthalamic nucleus; in children, it is usually associated with chorea and seen in cerebral palsy, kernicterus, Sydenham chorea and lupus erythematosus.


Tardive dyskinesia is a complex syndrome usually characterized by buccolingual masticatory movements that include tongue protrusion, lip smacking, puckering, and chewing. It is decidedly uncommon in children. Dopamine antagonist drugs (neuroleptics and antiemetics) are the usual cause of tardive dyskinesia. It may be a subtype of chorea, or at least a related disorder, and is sometimes associated with choreiform movements of the limbs. Most children thought to have developed tardive dyskinesia usually turn out to have motor tics. The incidence of tardive dyskinesia with both first and second generation neuroleptic drugs (0.3–0.4 % and 0.77 %, respectively) in children is significantly less than the rates reported in adults (0.6–0.8 % and 5%, respectively) ( ).


Boxes 14-1 and 14-2 summarize the differential diagnosis of chorea and choreoathetosis. Chorea is a cardinal feature of the conditions listed in Box 14-1 . The details of many such conditions are elsewhere in the text because concurrent features are more prominent. Although abnormal movements are the only manifestation, the description of familial paroxysmal choreoathetosis is in Chapter 1 because it is more likely to be confused with epilepsy than with other causes of chorea.



BOX 14-1





  • C ardiopulmonary B ypass S urgery



  • G enetic D isorders




    • Abetalipoproteinemia (see Chapter 10 )



    • Ataxia-telangiectasia (see Chapter 10 )



    • Benign familial chorea



    • Fahr disease



    • Familial paroxysmal choreoathetosis (see Chapter 1 )



    • Glutaric aciduria



    • Hepatolenticular degeneration (Wilson disease)



    • Huntington disease (see Chapter 5 )



    • Lesch-Nyhan syndrome (see Chapter 5 )



    • Machado-Joseph disease (see Chapter 5 )



    • Neuroacanthocytosis




  • D rug -I nduced M ovement D isorders




    • Anticonvulsants



    • Antiemetics


      Denotes the most common conditions and the ones with disease modifying treatments




    • Oral contraceptives



    • Psychotropic agents



    • Stimulants



    • Theophylline




  • S ystemic C onditions




    • Hyperthyroidism



    • Lupus erythematosus



    • Pregnancy (chorea gravidarum)



    • Sydenham (rheumatic) chorea




  • T umors of C erebral H emisphere ( see C hapter 4 )



Differential Diagnosis of Chorea as an Initial or Prominent Symptom


BOX 14-2





  • A lternating H emiplegia (see C hapter 11 )



  • B ilateral S triatal N ecrosis (see D ystonia )



  • C erebral P alsy


    Denotes the most common conditions and the ones with disease modifying treatments





  • G enetic D isorders




    • Ceroid lipofuscinosis (see Chapter 5 )



    • Guanidinoacetate methyltransferase deficiency (see Chapter 1 )



    • Idiopathic torsion dystonia



    • Incontinentia pigmenti (see Chapter 1 )



    • Pantothenate kinase-associated neurodegeneration



    • Pelizaeus-Merzbacher disease (see Chapter 5 )



    • Phenylketonuria (see Chapter 5 )



    • Porphyria (see Chapter 7 )




  • I nfectious D iseases





  • M etabolic E ncephalopathies (see C hapter 2 )




    • Addison disease



    • Burn encephalopathy



    • Hypernatremia



    • Hypocalcemia



    • Hypoparathyroidism



    • Vitamin B12 deficiency




  • R ett S yndrome (see C hapter 5 )



  • V ascular





Conditions That May Include Chorea


Box 14-2 contains a partial list of conditions in which chorea and choreoathetosis may occur, but in which they are either late features or at least not prominent early in the course. Movement disorders are a relatively common feature of several cerebral degenerative disorders. In contrast, chorea and seizures may be confused when chorea develops during an acute illness such as bacterial meningitis, metabolic encephalopathies, or encephalitis. At times, the movement disorder is due to the underlying brain disorder and at times to drugs used in treatment.


Cardiopulmonary Bypass Surgery


Severe choreoathetosis is a complication of up to 10 % of children with congenital heart disease following cardiopulmonary bypass surgery and profound hypothermia. Deep hypothermia and circulatory arrest are not essential factors in the pathophysiology but are often associated. The mechanism of basal ganglia injury is unknown.


Clinical Features


Most affected children are more than 1 year of age and have cyanotic heart disease with systemic to pulmonary collaterals. Choreoathetosis begins within 2 weeks postoperatively and may be associated with oral-facial dyskinesias, hypotonia, affective changes, and pseudobulbar signs. Some children have only mild chorea that resolves spontaneously within 2 months. Others may have severe exhausting chorea, unresponsive to treatment, which results in either death or severe neurological morbidity. Expect cognitive disturbance in half of survivors ( ).


Diagnosis


The clinical features are the only basis for diagnosis. Magnetic resonance imaging (MRI) results are often normal during the acute illness.


Management


Sedation prevents exhaustion in severely affected children. The choreoathetosis is often refractory to drug therapy. Clonazepam, gabapentin, and pregabalin may prove useful to reduce the movement.


Drug-Induced Chorea


Choreiform movements and akathisia or dystonic posturing may occur as effects of drugs, especially dopamine antagonists. Chorea is more often a consequence of the abrupt discontinuation of dopamine antagonist. Akathisia is more likely to be a dose-related effect, whereas dystonia is usually an idiosyncratic reaction (see the section on Dystonia later in this chapter). Phenytoin and ethosuximide may induce chorea as a toxic or idiosyncratic manifestation. Oral contraceptives may induce chorea. The mechanism is unknown. Neuroleptics are associated with idiosyncratic dystonic reactions and tardive dyskinesia, and stimulant drugs (dextroamphetamine and methylphenidate) are associated with chorea, akathisia, and tics (see the section on Tic and Tourette Syndrome later in this chapter).


Tardive Dyskinesia


The term tardive dyskinesia denotes drug-induced choreiform movements that occur late in the course of drug therapy. These movements are often limited to the lingual, facial, and buccal muscles. Drug-induced buccolingual dyskinesia is unusual in children.


Tardive dyskinesias are most often associated with drugs used to modify behavior (neuroleptics), such as phenothiazines, haloperidol, risperdone, quetiapine or olanzapine, and antiemetics such as metoclopramide and prochlorperazine; they also occur in children with asthma treated with theophylline. The estimated annual incidence of tardive dyskinesia in children taking neuroleptic drugs is less than 1 % ( ). The incidence after long-term exposure in children is reported as high as 9.8 %, still less than the 23.4 % reported in adults ( ).


Clinical Features


Tardive dyskinesia is a complex of stereotyped movements. It usually affects the mouth and face, resembles chewing, and includes tongue protrusion and lip smacking; the trunk may be involved in rocking movements and the fingers in alternating flexion and extension resembling piano playing. Limb chorea, dystonia, myoclonus, tics, and facial grimacing may be associated features. Stress exacerbates the movements and sleep relieves them.


Symptoms appear months to years after the start of therapy and are not related to changes in dosage. In children, discontinuing the drug usually stops the movement, but the movements may remain unchanged in adults.


Diagnosis


Drug-induced dyskinesia is suspected in any child who shows abnormal movements of the face or limbs while taking neuroleptic drugs. The distinction of tardive dyskinesia from facial tics is important in children with Tourette syndrome and the distinction of facial mannerisms from tics in children with schizophrenia.


Management


Discontinue all neuroleptic drugs as quickly as possible when symptoms of dyskinesia develop. This may not be practical when psychosis requires drug therapy. In such circumstances, the movements sometimes respond to diazepam.


Emergent Withdrawal Syndrome


Chorea and myoclonus may appear for the first time after abruptly discontinuing or reducing the dosage of neuroleptic drugs. Lingual-facial-buccal dyskinesia may be present as well. The symptoms are self-limited and cease in weeks to months. Slow tapering of neuroleptics reduces the possibility of this syndrome. Reintroduction of the medication with slower withdrawal may be helpful in cases triggered by abrupt removal of a dopamine blocking agent ( ).


Genetic Disorders


Cerebellar ataxia is often the initial feature of abetalipoproteinemia and ataxia-telangiectasia. Chorea may occur in both conditions, but only in ataxia-telangiectasia does chorea occur without ataxia. Huntington disease is an important cause of chorea and dystonia, but in children the initial feature is declining school performance. The discussion of Huntington disease in children is in Chapter 5 .


Benign Familial (Hereditary) Chorea


Benign familial chorea is a rare disorder transmitted by autosomal dominant inheritance ( ). The gene locus is on chromosome 14q. Benign familial chorea and familial paroxysmal choreoathetosis (see Chapter 1 ) may be genetically related disorders.


Clinical Features


The onset of chorea is usually in early childhood, often when the child is beginning to walk. Delayed motor development may be associated. Other possible features are intention tremor, dysarthria, hypotonia, and athetosis. Intelligence is normal. Most children have only chorea, which declines in intensity by adolescence. Adults may be asymptomatic or may have mild hypotonia and ataxia.


Diagnosis


Benign familial chorea may be difficult to distinguish from other causes of chorea in children, especially familial paroxysmal chorea. A family history of the disorder is critical to diagnosis, but difficult to obtain when parents show incomplete expression. Chorea is continuous and not episodic or paroxysmal. Neuroimaging studies and EEG results are normal.


Management


Chlorpromazine or haloperidol is beneficial in some individuals.


Fahr Disease


Fahr disease is the combination of encephalopathy and progressive calcification of the basal ganglia. Idiopathic basal ganglia calcification (IBGC) is another term applied to the same condition ( ). Calcification of the basal ganglia occurs with infectious, metabolic, and genetic disorders. Inheritance of IBGC disease is as an autosomal dominant trait (chromosome 14q). Most affected people are asymptomatic ( ). The pathogenesis is unclear.


Clinical Features


Onset may be in childhood, but the usual age is in the third to fifth decades. The core clinical features of IBGC are neuropsychiatric and movement disorders. The expression of IBGC varies within a family.


Diagnosis


Diagnosis requires bilateral calcification of the basal ganglia associated with neurological deterioration and the absence of an underlying metabolic disorder. The most common area of calcification is the globus pallidus. However, additional areas of involvement include the putamen, caudate, dentate, thalamus, and cerebral white matter. Every child with basal ganglia calcification requires assessment of parathyroid function to exclude the possibility of either hyperparathyroidism or pseudohypoparathyroidism.


Management


Specific treatment is not available. Symptoms may respond to drug therapy.


Neuroacanthocytosis (Choreoacanthocytosis)


The term neuroacanthocytosis encompasses several disorders including autosomal recessive chorea-acanthocytosis and X-linked McLeod syndrome ( ). Familial and nonfamilial cases of a progressive neurological disorder exist in which the main features are chorea and acanthocytosis with normal lipoprotein levels. The acanthocyte is an abnormal erythrocyte that has thorny projections from the cell surface. Acanthocytosis occurs in at least three neurological syndromes: McLeod syndrome (see Chapter 8 ), neuroacanthocytosis, and abetalipoproteinemia (see Chapter 10 ). The clinical features in severe cases of McLeod syndrome may be similar to those of neuroacanthocytosis.


Clinical Features


Onset is usually in adult life but may occur as early as the first decade. The most consistent neurological findings are impairment of frontal lobe function and psychiatric symptoms. Tics, oromandibular dyskinesia and dystonia, and self-mutilation of the lips may be associated features. Phenotypic variability is considerable and may include axonal neuropathy, loss of tendon reflexes, dementia, seizures, and neurosis.


Diagnosis


The association of acanthocytes or echinocytes (cells with rounded projections) and neurological disease in the absence of lipoprotein abnormality is required for diagnosis. Exclusion of McLeod syndrome is by testing for the Kell antigen.


Management


Only symptomatic treatment is available. Death occurs 10 to 20 years after onset.


Paroxysmal Choreoathetosis


Paroxysmal choreoathetosis occurs in children who are otherwise normal and in children with an obvious underlying static encephalopathy. The normal children have a genetic disease, familial paroxysmal choreoathetosis (see Chapter 1 ), and the abnormal children may have one of several nongenetic disorders. Acquired paroxysmal choreoathetosis occurs most often in children with cerebral palsy. Either hemiplegia or diplegia may be present, and the involuntary movements affect only the paretic limbs. The onset of the movement disorder often begins 10 or more years after the acute encephalopathy.


Systemic Disorders


Hyperthyroidism


Chapter 15 discusses the ocular manifestations of thyrotoxicosis. Tremor is the most common associated movement disorder. Chorea is unusual, but, when present, may affect the face, limbs, and trunk. The movements cease when the child becomes euthyroid.


Lupus Erythematosus


Clinical Features


Lupus-associated chorea is uncommon but may be the initial feature of the disease. Onset of symptoms is 7 years before to 3 years after the appearance of systemic features. It is indistinguishable from Sydenham chorea in appearance. The average duration is 12 weeks, but one-quarter of patients have recurrences. Additional neurological features of lupus (ataxia, psychosis, and seizures) are common in children who have chorea but occur only after the appearance of systemic symptoms. Therefore, chorea may be a solitary manifestation of disease.


Diagnosis


The diagnosis is clear in children with known lupus erythematosus. When chorea is the initial feature of lupus, the diagnosis is more problematic. The erythrocyte sedimentation rate may be elevated in both lupus and Sydenham chorea and is not a distinguishing feature. The presence of elevated concentrations of antinuclear antibodies and anti-DNA lupus antibodies is critical to diagnosis.


Management


The treatment of children with neurological manifestations of lupus erythematosus requires high doses of corticosteroids. The overall outcome is poor.


Pregnancy (Chorea Gravidarum)


Chorea of any cause beginning in pregnancy is chorea gravidarum. Rheumatic fever was once the most frequent cause but it is now the antiphospholipid antibody syndrome, with or without systemic lupus erythematosus.


Clinical Features


The onset of chorea is usually during the second to fifth month of pregnancy but may begin postpartum. Cognitive change may accompany the chorea. Symptoms usually resolve spontaneously within weeks to months.


Diagnosis


Women who develop chorea during pregnancy require studies for the rheumatic fever, antiphospholipid antibody syndrome, and systemic lupus erythematosus.


Management


This is a self-limited condition, and drugs should be used cautiously so as not to harm the fetus. Pimozide, risperidone and haloperidol may be useful.


Sydenham (Rheumatic) Chorea


Sydenham chorea is the most common cause of acquired chorea in children. It is a cardinal feature of rheumatic fever and is sufficient alone to make the diagnosis. Rheumatic chorea occurs primarily in populations with untreated streptococcal infections. One hypothesis is that a mistaken antibody attack against cells in the basal ganglia occurs after exposure of genetically predisposed children to group A, β-hemolytic streptococcus infection.


Clinical Features


The onset is frequently insidious and diagnosis often delayed. Chorea, hypotonia, dysarthria, and emotional lability are cardinal features. Difficulty in school may bring the child to medical attention. Chorea causes the child to be restless, and discipline by the teacher results in emotional stress. Obsessive-compulsive behavior may be present and the behavioral change considered a sign of mental illness.


Examination reveals a fidgeting child with migratory chorea of limbs and face. Initially, the chorea may be unilateral, but eventually becomes generalized in most patients. Efforts to conceal chorea with voluntary movement only add to the appearance of restlessness. Gradual improvement occurs over several months. Most recover completely. Rheumatic valvular heart disease develops in one-third of untreated patients.


Diagnosis


The clinical features establish the diagnosis. Laboratory tests are not confirmatory. The differential diagnosis includes lupus-associated chorea and drug-induced chorea. Examine the blood for lupus antinuclear antibodies and thyroid function. The onset of Sydenham chorea is usually 4 months after the provocative streptococcal infection, and the antistreptolysin O titer may be then back to normal or only slightly increased. During the time of illness, T 2 -weighted MRI images may show increased signal intensity in the putamen and globus pallidus that resolves when the child has recovered.


Management


Most importantly, evaluate the heart by echocardiogram as subclinical valvular involvement is common and changes the management with addition of aspirin and close monitoring. Dopamine blocking agents such as pimozide usually control acute neurological symptoms without producing sedation. If pimozide does not relieve the symptoms, benzodiazepines, phenothiazines, or haloperidol are therapeutic options. The treatment of all children with Sydenham chorea is the same as for acute rheumatic fever: penicillin in high doses for 10 days to eradicate active streptococcal infection and prophylactic penicillin therapy until age 21.




Dystonia


Repetitive muscle contractions that are sustained at the peak and result in torsional postures characterize dystonia. The appearance is one of an abnormal posture rather than an involuntary movement. The muscle contractions can affect the limbs, trunk, or face ( grimacing ). Involvement may be of a single body part ( focal dystonia ), two or more contiguous body parts ( segmental dystonia ), the arm and leg on one side of the body ( hemidystonia ), or one or both legs and the contiguous trunk and any other body part ( generalized dystonia ).


Box 14-3 summarizes the differential diagnosis of abnormal posturing. Continuous motor unit activity (see Chapter 8 ) may be difficult to distinguish from dystonia by clinical inspection alone, especially when only one or two limbs are affected. Electromyography distinguishes the two disorders in many cases.



BOX 14-3





  • Dystonia


    Denotes the most common conditions and the ones with disease modifying treatments




  • Hysteria



  • Muscular dystrophy



  • Myotonia



  • Neuromyotonia



  • Rigidity



  • Spasticity



  • Stiff man syndrome



Differential Diagnosis of Abnormal Posturing


Persistent focal dystonias are relatively common in adults but are unusual in children except when drug induced. Most dystonias in children begin focally and eventually become generalized. Children with focal, stereotyped movements of the eyelids, face, or neck are much more likely to have a tic than focal dystonia. Box 14-4 lists childhood forms of focal dystonia.



BOX 14-4


Focal Dystonia





  • Blepharospasm



  • Dopa-responsive dystonia


    Denotes the most common conditions and the ones with disease modifying treatments




  • Drug-induced dystonia



  • Generalized dystonia beginning as focal dystonia



  • Torticollis



  • Writer’s cramp



Generalized Genetic Dystonias





  • Ataxia with episodic dystonia (see Chapter 10 )



  • Ceroid lipofuscinosis (see Chapter 5 )



  • Dopa-responsive dystonia



  • Familial paroxysmal choreoathetosis (see Chapter 1 )



  • Glutaric acidemia type I



  • Hallervorden-Spatz disease



  • Hepatolenticular degeneration (Wilson disease)



  • Huntington disease (see Chapter 5 )



  • Idiopathic torsion dystonia



  • Infantile bilateral striatal necrosis



  • Leber disease (see Chapter 16 )



  • Machado-Joseph disease (see Chapter 10 )



  • Mitochondrial disorders (see Chapter 5 , Chapter 8 , Chapter 11 )



  • Transient paroxysmal dystonia of infancy (see Chapter 1 )



Generalized Symptomatic Dystonias





  • Perinatal cerebral injury (see Chapter 1 )



  • Postinfectious



  • Poststroke



  • Posttraumatic



  • Toxin-induced



  • Tumor-induced



Hemidystonia





  • Alternating hemiplegia (see Chapter 11 )



  • Antiphospholipid syndrome (see Chapter 11 )



  • Basal ganglia tumors



  • Neuronal storage disorders


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Mar 3, 2019 | Posted by in NEUROLOGY | Comments Off on Movement Disorders
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