2.  What causes movement disorders?

Movement disorders originate deep within the central nervous system. They are triggered by changes to specific regions of the brain or nervous system controlling movement. People with a movement disorder suffer from a breakdown in the normal flow of neurological messages and this leads to involuntary muscle movement. They may lose the ability to control these impromptu movements, or to properly coordinate their voluntary movements.

Learn more about the causes of the following movement disorders:

  1. Parkinson's disease
  2. Spasticity
  3. Essential Tremor
  4. Dystonia

Parkinson's disease

While the exact causes are unknown, we now know that Parkinson's disease develops following a loss of cells in specific parts of the brain. A consensus has emerged that most cases of Parkinson's are caused by a combination of environmental and genetic factors, and that the combination may be different for different people.

Many symptoms of Parkinson's disease involve motor control, the four most common categories being:

Rigidity, or resistance to movement, affects most patients and usually begins in the legs or neck. The affected muscles will remain tense and contracted, and some patients may feel pain as well as stiffness. Attempting to move the limb of a patient in Rigidity may lead to short, jerky movements called 'cog-wheeling'.

Slowness of movement (bradykinesia - pronounced 'bray-dee kin-eesya') is one of the classic symptoms of Parkinson's disease. Over time, patients develop a stooped posture and a slow, shuffling walk. This gait gradually becomes erratic and unsteady, and may lead to falls. Eventually spontaneous and automatic movement is lost and, after a number of years, the muscles may not move at all. This is then known as akinesia (pronounced 'ay-kin-eesya').

Symptoms often start with an occasional tremor in just one finger - but over time they will spread to the entire arm. The tremor is often rhythmic and will frequently cause an action of the thumb and fingers known as 'pill-rolling'. The tremor will be present when the limb is at rest or held up without support, but disappears briefly during movement. You may find the only one side of the body is affected by tremors, particularly in the early stages of the disease.

Postural instability
As it sounds, Postural instability gives patients a stooped position with bowed head and drooped shoulders. Impaired balance and coordination causes some patients to develop a forward or backward lean. Patients with a backward lean may also develop a tendency to step backwards, in 'retropulsion'. For some patients, postural instability also leads to repeated falls with serious injuries as a result.

Other symptoms
When considering Parkinson's disease, it is important to be aware of its non-motor symptoms and effects. These can include depression, anxiety, pain and sexual dysfunction.

If you are suffering from Parkinson's disease, discuss treatment options with your doctor, and ask for a referral to a movement disorder specialist near you.


Spasticity can occur when neurological disorders or injuries damage parts of the motor pathways that control voluntary movement. It occurs when muscles receive improper nerve signals and contract - they become tense and short when they should be relaxed or unflexed.

The most common causes of Spasticity include cerebral palsy, spinal cord injury, multiple sclerosis, stroke, and traumatic brain injuries (such as lack of oxygen, physical trauma, haemorrhage, or infection).

Spasticity may not be present all the time. It can be brought on by rapid movement or by sensory stimulation. So an important part of both care and treatment is minimizing possible causes of these stimuli, including pain, pressure sores, urinary tract infection, ingrown toenails, restrictive clothing, constipation, and so on.

Spasticity in multiple sclerosis
In Australia more than 10,000 people suffer from multiple sclerosis. The disease is more common in northern climates, and in caucasians. Incidences of MS are also more common in higher socio-economic groups, and more than twice as common among women as men.

Of those people with MS, more than 85 percent have at least mild spasticity, with more than 30 percent of those being forced to frequently modify their activities as a result.

Spasticity in Cerebral Palsy
Cerebral palsy is estimated to affect two to three of every 1,000 live births in Australia. About 75 percent of cerebral palsy incidences are related to pre-birth events.

Spasticity in stroke
Every year over 50,000 Australians are admitted to hospital as a result of a Stroke. Overall, 85 out of every 1,000 people older than 65 have had a stroke - and this rate increases with age, particularly among women.

Spasticity in traumatic brain and spinal cord injury
According to the latest statistics*, some 27,500 Australians are admitted to hospital with a traumatic brain injury each year. And of approximately 10,000 people in Australia who live with a disability related to spinal cord injury, more than half are thought to have spasticity. (*Australian Institute of Health and Welfare)

If you are suffering from spasticity, discuss treatment options with your doctor, and ask for a referral to a movement disorder specialist near you.

Essential Tremor

The symptoms of Essential Tremor can begin at any age from childhood through to late adulthood, with an average onset age of about 45 years.

The cause of ET is unknown. It may occur sporadically and it can be inherited. In familial (inherited) cases, children of affected people have a 50 percent risk of inheriting the gene for Essential Tremor and eventually developing the disease. However, carrying the ET gene does not always lead to symptoms of tremor.

Essential Tremor requires a clinical diagnosis; there is no definitive test. The condition can therefore remain undiagnosed if people delay seeking medical advice for their worsening symptoms. ET is best diagnosed by a movement disorder specialist who has experience with ET patients.

Some of the differences between ET and Parkinson's disease (Pd) are:

  • Pd tremors generally occur at rest, whereas ET tremors will occur during activity but be absent when the patient rests.
  • Pd patients also exhibit other symptoms, such as slowness and stiffness, while ET patients may only have the tremor symptom.
  • Pd medication does not work for people with ET.

If you are suffering from Parkinson's disease, discuss treatment options with your doctor, and ask for a referral to a movement disorder specialist near you.


Dystonic movements are associated with prolonged bursts of electrical activity in affected muscle(s) and they tend to be of a sustained, directional nature rather than the rhythmic, 'back-and-forth' movement of a tremor. However, tremor-like muscle spasms, tremulous movements or dystonic tremors may manifest themselves when the patient attempts to actively resist the abnormal, involuntary movements of dystonia.

Dystonic spasms typically increase in intensity during stress, emotional upset, or fatigue. Spasms tend to decrease in intensity during periods of rest or sleep. Many people can temporarily suppress dystonic movements or spasms by 'sensory tricks'. These tricks usually consist of touching the affected or adjacent body parts. The phenomenon is almost unique to dystonia, and may therefore play a helpful role in differential diagnosis.

To understand the cause of dystonia, it's important to look at the ways dystonia is classified. Each person will have a combination of the following symptoms, which will define their condition and its likely cause:

Age of Onset Location in body Underlying cause
Child Focal Primary
Adolescent Segmental Secondary
Adult Multifocal Heredodegenerative

Underlying causes

Primary Dystonia

People with primary dystonia will only exhibit dystonic symptoms, with the possible exception of tremor.

Disease genes have been identified as a common underlying cause of primary dystonia, however the condition can still occur in the absence of any family history. Most primary dystonias are sporadic, have adult onset, and are focal or segmental in nature.

Secondary (Symptomatic) Dystonia

Secondary dystonia refers to dystonia that results from environmental factors, peripheral injuries, or damage to the brain or spinal cord. Causes of secondary dystonia include:

  • Abnormalities of brain function such as cerebral palsy
  • Vascular malformations of the brain, in which a tangle of abnormal blood vessels form links between the arterial and venous systems
  • Brain tumors
  • Brainstem lesions
  • Head injury
  • Inflammatory and infectious conditions affecting the brain (encephalitis),and human immunodeficiency virus (HIV) infection
  • Stroke or localised brain damage due to either temporary interruption of the blood supply or leakage of blood outside blood vessel walls
  • Multiple Sclerosis (MS), a progressive disease of the central nervous system characterised by loss of myelin
  • Thalamotomy, a procedure involving surgical destruction of a selected region of the thalamus, which is a section of the brain involved in regulating movement.
  • Injury or lesions of the spinal cord within the neck region (cervical spinal cord)
  • Narrowing of the spinal cavity within the spinal column at the lower back region.
  • Peripheral trauma, which may be followed by focal dystonia in the affected body part
  • Certain metabolic conditions such as decreased activity of the parathyroid glands
  • Prolonged or substantial exposure to toxic environmental agents, such as carbon monoxide, cyanide, manganese, or methanol
  • Therapy with certain medications, such as:
    • Particular anticonvulsant medications
    • Dopamine receptor blockers, such as certain antipsychotic drugs, antidepressants and antinausea medications. In some patients, therapy with certain dopamine receptor blockers may result in a sudden onset of dystonia or the development of persistent dystonia known as tardive dystonia
    • Levodopa, a precursor of the neurotransmitter dopamine, for the treatment of Parkinson's disease

Heredodegenerative Dystonia

Heredodegenerative dystonia generally refers to inherited conditions. However the term also includes cases associated with other inherited diseases, for example:

  • Cross-linked dystonia-parkinsonism (Lubag)
  • Huntington's disease
  • Wilson's disease
  • Neuroacanthocytosis (a rare movement disorder marked by progressive muscle weakness and atrophy, progressive cognitive loss)
  • Rett syndrome
  • Parkinson's disease
  • Juvenile parkinsonism
  • Hallervorden-Spatz (a rare, inherited, neurological movement disorder characterised by progressive degeneration of the nervous system)

Location in the body

Dystonia usually begins in a single body part. It may then remain restricted to that area or it may spread to another region or regions. In addition to the classifications mentioned above, physicians also classify dystonia by where it affects the body:

  • Focal - limited to one area of the body
  • Segmental - affecting 2 or more nearby or contiguous areas of the body
  • Multifocal - involving 2 or more distant regions of the body
  • Hemidystonia - affecting one half of the body
  • Generalised - leg involvement plus eventual involvement of another region or regions of the body

Focal Dystonias

Focal dystonias often become apparent during a person's 40s or 50s. However, symptoms may become obvious earlier in life. Women are affected approximately three times more frequently than men.

The symptoms associated with the focal dystonias are variable and depend upon the intensity and severity of the spasms and the specific body region and muscle groups involved. The rate of progression from the onset of symptoms to the point where a patient has difficulty with everyday activities can range from days or weeks to a period of several years.

Symptoms of a focal dystonia may only be periodic at first, occurring during stressful periods or at random. Symptoms will tend to appear when the affected body part performs certain movements and typically disappear when the affected area is at rest. However, as the disease progresses, dystonic spasms begin to be associated with other activities of the affected region. Symptoms may also occur in association with voluntary actions involving other bodily areas. This is known as overflow.

Eventually, dystonic symptoms may be present even when the affected part is at rest. Gradually, the affected area may assume an unusual and sometimes painful posture.

Focal dystonias may extend to involve nearby areas, resulting in segmental dystonia in up to 30 percent of patients. It is less common for focal dystonia to evolve into multifocal dystonia.

Focal dystonia is usually considered to be a primary dystonia. In other words, the dystonia is the only sign of disease (with the possible exception of tremor) and secondary causes can be excluded. Adult-onset focal dystonias usually occur in the absence of a family history. In some relatively rare cases, more than one family member may be affected.

Commonly described forms of focal dystonia include:

  • Cervical dystonia (spasmodic torticollis)
  • Blepharospasm
  • Oromandibular dystonia
  • Laryngeal dystonia (spasmodic dysphonia)
  • Limb dystonia

Segmental Dystonia

When dystonia affects two areas of the body that are next to each other, this is termed segmental dystonia. Dystonic spasms affect at least two adjacent areas of the body, such as facial and neck muscles; muscle groups of the neck and upper arm; or trunk and leg muscles.

One common segmental dystonia involves muscles of the eyelids, jaw, mouth, and lower face. Known as Meige syndrome, the condition is characterised by periodic or sustained closure of the eyelids (blepharospasm). This form of segmental dystonia may spread to neck muscles or other muscle groups. Meige syndrome more frequently affects women than men and typically becomes apparent during their 60s.

Multifocal Dystonia

Multifocal dystonia affects two or more non-adjacent areas of the body, such as both legs; one or both arms and a leg; or the face and a leg.


Hemidystonia is a form of dystonia that affects one whole side of the body or is characterised by unilateral involvement of the upper and lower limbs. It is considered as a type of multifocal dystonia. Hemidystonia typically occurs as a result of other underlying conditions, particularly Multiple Sclerosis, tumor, stroke, or vascular malformations.

Generalised Dystonia

In people with generalised dystonia, dystonic spasms involve the legs or one leg and the trunk as well as one other area of the body. Unlike primary focal dystonias, the onset of primary generalised dystonia will typically occur at a younger age.

Age of onset

Symptoms of dystonia may become apparent during childhood, adolescence, or adulthood and are classified as:

  • Childhood onset - 0 to 12 years
  • Adolescent onset - 13 to 20 years
  • Adult onset - older than 20 years

With primary dystonia, the age of symptom onset is an important indicator of whether the dystonia will potentially progress to involve other body regions. Typically, the younger the patient at symptom onset, the greater the likelihood that dystonia will eventually affect other areas of the body. In people with primary dystonia under the age of 20 years, the symptoms will usually start in a leg or arm then progress to the other limbs and the trunk. Childhood or adolescent onset with initial involvement of a leg is considered an key indicator of eventual progression to generalised dystonia.

The older the patient at symptom onset, the greater the likelihood that the dystonia will remain localised, potentially with limited involvement of adjacent regions. In people with primary adult onset dystonia, the dystonia often begins in the upper body, such as the neck, head, or an arm.

If you are suffering from a movement disorder, discuss treatment options with your doctor, and ask for a referral to a movement disorder specialist near you.

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