Movement Disorders In Depth

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Movement disorders can result from many types of brain injury, such as head trauma, infection, inflammation, metabolic disturbances, toxins or unintended side effects of medications. They can also be a symptom of other, underlying diseases or conditions, including genetic disorders.

The brain structures that are affected are thought to include the basal ganglia, the motor portions of the cortex, the thalamus, the cerebellum and/or brainstem. All these structures are thought to act together in a network, so damage to just one might be enough to cause a movement disorder.

Treatment of movement disorders often focuses on correcting the underlying cause. How well a child will do depends on the type of movement disorder, its cause, how well the movement disorder is treated and how soon treatment is started.

For example, a child with primary dystonia can live a normal life if she is treated early, whereas dystonia that goes undiagnosed and untreated for many years can become permanently disabling. Other movement disorders, such as tic disorders, may eventually go away on their own or become much milder.

If the movement disorder is part of a serious genetic or degenerative disorder, there may be no curative treatment. In most cases, though, there are interventions that can relieve children’s symptoms, in some cases dramatically.

Types of movement disorders include:

Chorea

Chorea is a symptom of a neurologic injury, not a disease in and of itself. Children with chorea have irregular, flowing movements that are sometimes described as “dance-like.” Sometimes the movements are incorporated into motions the child intends to make. They can be slow and writhing (athetosis) or more forceful (ballismus). If chorea affects the legs, children may frequently stumble and have difficulty walking but rarely fall.

Chorea in children can be caused by a brain injury at birth, head trauma, infection, inflammation or as a toxic reaction to medications. In some cases, it can have a genetic cause. Specific types of chorea include:

  • Syndenham chorea, also called rheumatic encephalitis, is a short-lived, autoimmune form of chorea that can occur as an after-effect of a group A strep infection.
  • Juvenile Huntington disease is a very rare genetic form of chorea not seen commonly in children.
  • Chorea from genetic causes, such as NKX2.1 mutations, may occur by itself or as part of a larger spectrum of neurological or other medical symptoms.

Tremor

Tremor is a rhythmic shaking or trembling of a limb. It sometimes occurs in children as a complication of an underlying illness or head injury, as a side effect of heavy medications or as a consequence of genetic disease. Tremor can occur at rest or during movement, can occur alone or be accompanied by other neurological symptoms such as weakness of the affected limb and difficulty in fine-tuning movements. Tremor also sometimes runs in families. The most common inherited form is known as essential tremor.

Sometimes tremor is just a temporary part of a child’s motor development; in other cases, it may be long-lasting. Unlike most other movement disorders, children can sometimes consciously suppress tremors.

Myoclonus

Myoclonus is a movement disorder involving very quick, sudden, involuntary muscle jerks that the child cannot suppress. The jerks can be occasional or frequent, and may occur randomly or in a semi-rhythmic pattern. Myoclonus sometimes has triggers, like holding the body in a certain posture, being touched or startled; or symptoms may seem to appear for no reason.

Myoclonus is frequently a benign condition with no long-term effect on a child’s health, but it is critical to be evaluated by a movement disorders specialist to identify the type of myoclonus and its cause.

Myoclonus may occur after a severe brain injury, or can result from a metabolic disorder or a neurodegenerative disease. It can also be part of a seizure disorder called myoclonic epilepsy, and for that reason, it’s often recommended that children with myoclonus be tested for epilepsy.

Occasionally, a child will have myoclonus alone without any accompanying problem. There is also a benign form of myoclonus that affects newborns during sleep and usually goes away by 6 months of age, and another benign form that begins at about 6 months of age and goes away within 6 to 18 months.

Dystonia

In children with dystonia, faulty brain signals cause groups of muscles to contract abnormally. Rather than contracting in a coordinated fashion, muscles may contract in opposition to each other: both “push” and “pull” muscles are active at the same time, causing painful or uncomfortable twisting movements and awkward, contorting postures.

Dystonia is often triggered by specific actions, like writing or walking, but can also occur when the child is at rest. Symptoms often start in one part of the body, such as the hand, leg or mouth, and then spread to other body areas. Early on, dystonia can be treated with oral medications or Botox injections, but if it is allowed to progress without treatment, it can eventually damage joints and muscles as limbs “freeze” into the dystonic position. Deep brain stimulation surgery early in the course of the dystonia, before fixed deformities develop, is an important treatment to consider for certain children; for others, surgically implanting a medication pump may be the best option.

  • Primary dystonia is thought to be genetic. Children with primary dystonia do not have any accompanying neurologic disorder. Primary dystonia tends to progress and spread most rapidly in the first five years after onset, then begins to stabilize. Most children with primary dystonia have a normal life expectancy, but dystonia can severely limit a child’s movements if left untreated.
  • Secondary dystonia, the most common form of dystonia in children, results from a brain injury (during birth, from a stroke or trauma, or from an inherited degenerative syndrome or metabolic disorder). The severity and symptoms of secondary dystonia vary depending on its underlying cause. Secondary dystonia often occurs together with spasticity, and 5 to 15 percent of children with cerebral palsy also have dystonia.

Tic disorders/Tourette syndrome

Tics are sudden, involuntary movements or sounds that come and go over time. They are fairly common in children and usually can be treated by a general pediatrician. Muscle tics can involve any body part and may vary in severity—from very mild and hardly noticeable to very disruptive, frequent and severe. Children are usually able to suppress tics, at least temporarily, but will feel a building sense of “wrongness” or “push” as they resist the tic.

If tics persist despite treatment, it may be beneficial for the child to see a specialist in movement disorders. About 10 to 15 percent of children will see their tics progress and become potentially disabling, but most tic disorders resolve or become minimal by the time a child reaches her 20s.

If a child has both vocal and motor tics that last longer than a year, they are considered to have Tourette syndrome. Many children with Tourette syndrome also have attention deficit hyperactivity disorder (ADHD), obsessive-compulsive disorder (OCD) or learning disorders, which can be evaluated and treated by a child neurologist or developmental pediatrician.

Parkinsonism

A child is considered to have parkinsonism if she has at least two symptoms shared by adults with Parkinson disease: muscle rigidity, balance problems or frequent falls, slow movement (bradykinesia) or tremor while at rest. By itself, parkinsonism is the least common movement disorder in children. Most often, the symptoms occur as a side effect of medications. Parkinsonism can also result from genetic conditions causing brain degeneration, such as Wilson disease, juvenile Huntington disease and lysosomal disorders, and from various forms of brain injury. As with adult Parkinson disease, treatment usually includes a trial of dopamine supplementation (levodopa), with side effects carefully monitored.

Ataxia

Ataxia is a failure of motor coordination caused by injury or dysfunction of the cerebellum. Its symptoms are clumsiness, poor balance, irregularity of movements and inability to perform fine-tuned or smooth movements.

Ataxia can have different patterns. Some cases begin abruptly, as a result of a stroke or brain bleed, inflammation or infection, and typically resolve as these causes are treated. Other types of ataxia repeatedly come and go, and are caused by epilepsy, genetic mutations, metabolic disorders or atypical types of migraine. There are also progressive forms of ataxia caused by various inherited genetic conditions known as the spinocerebellar ataxias.

Functional neurological disorders/conversion disorder

In addition to the above conditions, it is not uncommon for movement disorders in children to follow stressful life events. A condition known as functional neurological symptom disorder, sometimes called conversion disorder, can cause any of the movement disorders described above, even when no neurologic cause or condition can be identified. Functional disorders also can occur in children with other neurological diagnoses and make an existing movement disorder worse. Even though no physical cause can be discovered, these disorders can be just as disabling as the types of movement disorders described above. The good news is that most children recover from this type of movement disorder with retraining by physical therapists and continued supportive care from a neurologist. In some cases, children may benefit from joined care with a psychologist or psychiatrist.

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