Movement disorders

How does movement work?

Even a simple action such as picking up a pencil engages several different parts of the brain. The conscious thought areas of the brain trigger the motor area to send signals to the muscles of the arm.
As the movement begins, sensors in the arm are activated, sending signals back into different areas of the brain that interpret them and then send further messages to the motor area to fine tune power, speed, coordination and balance.

Who's affected?

Given such complexity, problems with the control of movement are understandably widespread. Essential tremor - the most common movement disorder - affects one in 20 people under the age of 40 and one in five people over 65. Up to one in ten people has restless legs syndrome.
Other conditions such as Parkinson's disease (which affects one in 500 people) are less common, but can severely impair quality of life because they reduce the independence of those affected.

Dyskinesia

Dyskinesia simply means abnormal ('dys') movement ('kinesia'). Tics, spasm, athetosis (slow, writhing motions), chorea (rapid, randomly irregular jerky movements) and dystonia are all different types of dyskinesia.
The term 'paroxysmal' is also often used, to indicate the abnormal movements are sudden and unpredictable, with a fairly rapid return to normal.
Dyskinesia is often used to describe the movement difficulties of Parkinson's disease and similar disorders. They're also a common side-effect of certain drugs, such as L-dopa and antipsychotic medication.

Dystonia

In dystonia there are sustained or persistent contractions of one or more muscles. This leads to abnormal postures or writhing, twisting movements of part of the body. There are many different types, with various muscles involved. Writer's cramp is an example of focal dystonia (limited to one group of muscles), causing bizarre postures in one arm when writing or typing and disappearing at rest.
Blepharospas is a focal dystonia involving muscles that control closure of the eyelids. This leads to increased blinking and involuntary closing of the eyes.
Dystonias tend to be aggravated by tiredness, stress, anxiety and emotion.

Tics

Tics are involuntary rapid and repeated contractions of a group of muscles. This may cause movement, such as blinking, shrugging or grimacing, or the production of a sound.

Tremor

A tremor is an involuntary, rhythmic oscillation of a body part due to contractions of opposing muscles. There may be many causes. Everybody has a physiological tremor - that is, a very faint tremor in response to signals from the part of the brain called the cerebellum. Certain factors, such as exercise, emotional stress, or an overactive thyroid gland, can make this 'normal' tremor more prominent.
Essential tremor is as common as angina or stroke. It usually causes a tremor of the hands and feet, but the head and voice may also be affected. Very little is known about what goes on in the brain to cause essential tremor. It's often dismissed as insignificant, especially in elderly people, or misdiagnosed as Parkinson's disease.
But although it isn't fatal, it can cause severe disability. Essential tremor can be treated with drugs, including beta-blockers, or brain surgery in severe cases.

Dysphonia

Spasmodic dysphonia is a disorder of the voice caused by abnormal contraction of the muscles controlling the vocal cords. This results in a quivery, jerky or strained voice. There may be times when no sound can be made at all, while at other times the voice is fairly normal.

Ataxia

Ataxia is unsteady or poorly controlled movement due to problems with the control of coordination and balance. There are many different types. Ataxia may be a symptom of conditions such as multiple sclerosis or cerebral palsy, or it may be due to diseases of the cerebellum (a part of the brain). One simple and familiar cause of ataxia is alcohol consumption

Restless legs syndrome

Restless legs syndrome is an intensely uncomfortable sensation in the legs (and sometimes arms), which typically occurs with inactivity, especially around bedtime. The sensation, which has been described as tingling, creeping or 'bugs tunneling', is temporarily relieved by moving the limbs.
Other problems include disrupted sleep, insomnia and daytime fatigue. In most cases the cause isn't clear although it may be related to other conditions such as iron deficiency.
Relaxing bedtime routines can help, as can avoiding caffeine, nicotine and alcohol. The condition may be related to a disruption of brain chemical transmitters and medicines, for example those that increase the transmitter dopamine (such as those used to treat Parkinson's disease), can be effective in treating the syndrome.
There are many other movement disorders, including myoclonus, Huntington's disease, gait disorders, spasticity and progressive supranuclear palsy (PSP).
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