Definition

Chorea is an irregular, rapid, uncontrolled, involuntary, excessive movement that seems to move randomly from one part of the body to another.

The movements of chorea, athetosis, choreoathetosis, and ballism occur by themselves, without conscious attempts at movement.

The affected child often appears fidgety or restless and unable to sit still. The word "chorea" comes from the Greek word for dance. The jerky movements of the feet or hands are often similar to dancing or piano playing. When chorea is severe, the movements may cause motion of the arms or legs that results in throwing whatever is in the hand or falling to the ground. Walking may become bizarre, with inserted excessive postures and leg movements. Unlike parkinsonism, which is an inability to make voluntary movements, or ataxia and dystonia, which affect the quality of voluntary movements, the movements of chorea, athetosis, choreoathetosis, and ballism occur by themselves, without conscious attempts at movement. In some cases, attempts to move may make the symptoms worse.

Athetosis is a slower writhing and twisting movement. Choreoathetosis is a movement of intermediate speed, between the quick, flitting movements of chorea and the slower, writhing movements of athetosis. Ballism is a violent flinging of one or more limbs out from the body. Choreoathetosis is the most common form in children.

These disorders may affect the hands, feet, trunk, neck, and face. In the face, they often lead to nose wrinkling, continual flitting eye movements, and mouth or tongue movements. These disorders may be distinguished from tics, as tics tend to repeat the same set of movements. In addition, the child often describes a "build-up" in the need to make the tic, with a sense of release afterwards. There is no such sense of release following chorea; the movements are continually changing and flowing from one body part to another.

Examination

Mild chorea may be difficult to distinguish from normal restlessness. Therefore, it is important to assess whether the movements are controllable by the child and whether these movements are sustained or occur only in the doctor's office. It is important to note which parts of the body are involved. The speed and size of the movements determine whether this is most appropriately called chorea, athetosis, choreoathetosis, or ballism. For practical purposes, the distinction is often difficult to make; this distinction is not usually helpful in diagnosis and treatment.

The effect of purposeful movements, such as reaching, speaking, or walking, must be assessed. Dystonia may cause excessive and apparently random movements. These movements are usually worsened with intentional, attempted movements and improve when the child is at rest. There is no image of restlessness, although, in some cases of chorea, the symptoms may appear to be similar. Ataxia may lead to an abnormal gait, with extra movements needed to compensate; however, the movements disappear when the child is steadied or seated.

The history of other affected family members is critically important.

The timing of the chorea is important. There are paroxysmal types that only occur with sudden movement, exercise, or when the child is under stress. The age of onset is also important. In particular, mild chorea may be normal during the first few years of life, as long as it is not worsening over time. It is important to determine whether there are particular foods that trigger the symptoms, or whether there are clues to a metabolic disorder. These clues include intolerance of certain foods or episodes of unexplained vomiting and lethargy.

Genetics of Chorea
There are several genetic causes of chorea. The history of other affected family members is critically important to determining the need for special testing. Since chorea may be caused by exposure to medications or toxins, it is also important to determine whether any such exposure is possible. One more common cause of chorea is Sydenham's chorea, which often follows a streptococcal infection. For this reason, a history of sore throat or flu symptoms that preceded the onset of chorea is important. This history is not necessarily diagnostic as sore throats, flu symptoms, and even positive throat swabs for strep are common in children.

Mechanism

Chorea is thought to be caused by damage to the basal ganglia. As described in the section on anatomy and physiology, the basal ganglia can be divided into two fundamental pathways: the direct and the indirect pathways. In some cases, chorea seems to result from damage to the indirect pathway.

Chorea is thought to be caused by damage to the basal ganglia.

For example, chorea or ballism may be caused by injury to the subthalamic nucleus. Huntington's chorea is caused by selective loss of the indirect pathway cells in the striatum. Current theories suggest that the indirect pathway helps to inhibit unwanted movements, so it is possible that damage to this pathway allows the "escape" of movements that would ordinarily be suppressed. The random initiation of movements suggests that the indirect pathway serves not only to suppress unwanted movements but also to prevent the initiation of movement. It is not known why some children with diffuse injury to the basal ganglia (such as occurs in cerebral palsy) develop choreoathetosis, while others develop dystonia.

Etiology

Static (fixed) injury:
Cerebral palsy (often with delayed onset), encephalitis/post-encephalitis, trauma, tumors, kernicterus

Hereditary/Degenerative:
Ataxia-telangiectasia (AT), Fahr's disease, neurodegeneration with brain iron accumulation type I (NBIA-I, formerly called "Hallervorden-Spatz disease"), Huntington's disease (the dystonic-parkinsonian Westphal variant is more common in children), Rett syndrome, neuroacanthocytosis, HARP syndrome (hypoprebetalipoproteinemia, acanthocytosis, retinitis pigmentosa, and pallidal degeneration), benign hereditary chorea

Chemical/Metabolic:
Acyl-CoA dehydrogenase deficiency, mitochondrial disorders (e.g., Leigh's syndrome, etc.), Wilson's disease, GM1 gangliosidosis, metachromatic leukodystrophy, Lesch-Nyhan disease, Niemann-Pick disease type C, methylmalonic aciduria, nonketotic hyperglycinemia, Pelizaeus-Merzbacher disease, vitamin E deficiency or malabsorption (Bassen-Kornzweig disease), hypoparathyroidism, hyperthyroidism, propionic acidemia, hypernatremia, hypomagnesemia, hypocalcemia, hypoglycemia, hyperglycemia, post-cardiac bypass

Immune-mediated:
Lupus erythematosis, Henoch-Schonlein purpura, anticardiolipin or antiphospholipid antibody syndrome, Sydenham's chorea (associated with previous [one to six months] streptococcal infection), chorea gravidarum (during or immediately after pregnancy)

Vascular:
Basal ganglia stroke, cerebral vasculitis, Moya-Moya disease, complex migraine, alternating hemiplegia

Malformations:
Holoprosencephaly, Joubert syndrome, agenesis of the corpus callosum

Drug-induced:
Neuroleptic medications including anti-emetics (e.g., haloperidol, thorazine, clomipramine, pimozide, pemoline, compazine, metoclopramide, etc.), calcium channel blockers (e.g., flunarizine, cinarizine, etc.), amphetamines (e.g., ritalin and dexedrine, etc.), anti-seizure medications (e.g., phenytoin, carbamazepine, valproate, phenobarbital, etc.), anti-cholinergic medications (e.g., trihexphenydil, benztropine, etc.), anti-histamines, tricyclic antidepressants, benzodiazepines, stimulants (e.g., bronchodilators), clonidine, L-dopa, amantadine, cocaine, bismuth, lithium, manganese toxicity, ethanol, carbon monoxide, oral contraceptives, general anesthesia

Acute/Paroxysmal:
PKC: paroxysmal kinesogenic choreoathetosis (triggered by movement and responds to treatment with carbamazepine), PNKC: paroxysmal nonkinesogenic choreoathetosis (also known as paroxysmal dystonic choreoathetosis [PDC or Mount & Reback disease], often worsened by stress, caffeine, or alcohol, improved by clonazepam or acetazolamide, localized to a gene near 2q33-q35, also called DYT8), PEC: paroxysmal exercise-induced choreoathetosis (occurs with fatigue, rather than at the onset of movement).

Disorders that mimic chorea:
Spasmus nutans, tics, dystonia, shaking/shuddering spells, proprioceptive loss (e.g., spinal cord injury, peripheral neuropathy, etc.), self-stimulation, psychogenic, normal development (less than 1 year of age)

Workup

If the chorea is a new or acute symptom, it may be helpful to determine whether there has been a prior streptococcal infection (such as "strep throat"). It is known that Sydenham's chorea often follows such an infection. The importance of determining this is due to the fact that untreated streptococcal infections may lead to rheumatic fever. Up to 63% of children with Sydenham's chorea develop heart abnormalities. Sore throats and flu symptoms are very common and laboratory testing for streptococcus is not always reliable. Therefore, it may be difficult to determine if a previous streptococcal infection is the exact cause of a child's symptoms.

Laboratory tests may include a throat culture and streptococcal blood antigen test (ASLO), electrolytes (i.e., sodium, potassium, chloride, bicarbonate), magnesium, calcium, amino and organic acid studies, thyroid function, glucose, ammonia, antinuclear antigen (ANA), antiphospholipid antibodies (APLA), and a complete blood count (CBC). An additional test may be performed for the presence of acanthocytes.

In some cases, an MRI of the head may be important in order to look for structural abnormalities, such as those related to a tumor, stroke, metabolic or degenerative disorders, or a remote injury due to low oxygen.

Treatment

Chorea may be difficult to treat. If the child is taking any medications that can cause or worsen chorea, these should be tapered and discontinued, if possible. The mainstay of treatment in adults is the class of neuroleptics, including haloperidol and pimozide.

According to reports, certain anti-epileptic medications may help to improve the symptoms of chorea.

These drugs selectively enhance the function of the indirect pathway by blocking the inhibitory effect of dopamine on this pathway. However, the incidence of side effects in children from neuroleptics has been reported to be as high as 20%. Therefore, it is often safer to start with an alternative medication, such as a benzodiazepine, particularly clonazepam, diazepam, or clobazam. According to reports, certain anti-epileptic medications, such as valproate and piracetam, may improve the symptoms of chorea. In particular, valproate may be very helpful in children with Sydenham's chorea.

Last Update: January 3, 2002