What Is Dystonia? What Causes Dystonia?

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Main Category: Neurology / Neuroscience
Also Included In: Pain / Anesthetics;  Rehabilitation / Physical Therapy
Article Date: 18 Nov 2009 - 3:00 PDT

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Dystonia is a general term which describes involuntary movements and extended muscle contractions - a range of movement disorders. The patient has twisting body movements, tremor and unusual or awkward postures. For some patients the whole body may be involved in the movements, while for others only certain parts of the body are affected.

Dystonia symptoms may be linked to specific tasks, such as writing, as in writer's cramp. Dystonia may be inherited, but without a genetic pattern - a sporadic inheritance. People may develop dystonia symptoms as a result of taking certain medications. Some diseases, such as some forms of lung cancer may also produce signs and symptoms of dystonia.

Scientists have identified a gene responsible for at least one form of dystonia. Some patients respond well to dopamine, while others may benefit from sedative-type medications, or even surgery.

Although dystonia is a neurological condition, experts say that cognitive abilities (intelligence), memory, and communication skills are not affected.

According to Medilexicon's medical dictionary, dystonia is a "A syndrome of abnormal muscle contraction that produces repetitive involuntary twisting movements and abnormal posturing of the neck, trunk, face, and extremities."

According to the National Health Service (NHS), UK, approximately 38,000 people are affected by dystonia, out of a total population of 61 million.

Although most cases of dystonia start in patients aged between 40 and 60 years, it can hit all age groups.

Dystonia can be classified according to its underlying case:

• Primary dystonia - cases in which the only sign or symptoms is dystonia. The medical team cannot identify any disease or neurological damage that may have caused the dystonia.


• Secondary dystonia - when dystonia signs and symptoms occur as a consequence of an underlying condition - usually genetic, neurological or an injury which affects the nervous system.

Dystonia is also defined according to body part(s) affected:

• Focal dystonia - only one part of the body is affected.


• Segmental dystonia - two or more regions of the body are affected. The regions are somehow connected to each other, for example, the neck and shoulder.


• Multifocal dystonia - at least two regions of the body that are not connected to each other are affected. Such as an arm on one side as well as one leg on the other side of the body.


• Generalized dystonia - both legs and other regions of the body are affected.


• Hemidystonia - half of the entire body is affected.

Dystonia can also be classified according to age of onset:

• Early-onset dystonia - when dystonia signs and symptoms appear during the first thirty years of the patient's life. Symptoms are usually first noticed in a limb. Typically, the dystonia will eventually spread to other parts of the body.


• Late onset dystonia - most typically, onset of signs and symptoms appear in patients aged between 40 and 60 years. In the majority of cases symptoms start either in the neck, one of the arms or head, and generally do not spread.

What are the signs and symptoms of dystonia?

A symptom is something the patient feels and reports, while a sign is something other people, such as the doctor notice. For example, pain may be a symptom while a rash may be a sign.

Patients' signs and symptoms will depend mainly on the type of dystonia they have. Below are some common examples:

• Cervical dystonia - also known as toricollis; the most common form. Cervical dystonia affects only one body part (focal dystonia) and generally starts later on in life (late-onset dystonia). The neck muscles are affected. The patient may experience..
  
  
  • Twisting of the head and neck
  • Pulling forward of the head and neck
  • Pulling backwards of the head and neck
  • Pulling sideways of the head and neck
  
  Patients may experience mild to severe symptoms. If muscle spasms and contractions are frequent and severe enough, the patient may also experience stiffness and pain.
  
  Experts are not sure why, but say that touching the chin, neck or back of the head can often relieve symptoms considerably.


• Blepharospasm - the muscles around the eyes are affected. This is a focal (just one part of the body is affected), late-onset type of dystonia. The patient may experience..
  
  
  • Photophobia (sensitivity to light)
  • Irritation in the eye(s)
  • Excessive blinking, often uncontrollable
  • Eyes close uncontrollably. Patients with severe symptoms may find it impossible to open their eyes for several minutes.
  
  Signs and symptoms may become more and less severe depending on what time of day it is. The majority of patients find that symptoms worsen as the day progresses.


• Dopa-responsive dystonia - a type of generalized, early-onset dystonia (both legs and other parts of the body are affected, onset occurs from ages 5 to 30 years). This type of dystonia responds well to levodopa, a dopamine medication - hence the name.
  
  Typically, a patient will experience symptoms between 6 and 16 years of age. The most common symptom is a stiff, unusual walk, with the sole of the foot bent upwards. In some cases the foot may turn outwards at the ankle.
  
  Muscle stiffness and spasms in the arms and torso is not uncommon.


• Hemifacial spasm - This is a focal (just one part of the body is affected), late-onset type of dystonia. The patient experiences spasms in the muscles on one side of the face. Symptoms may be more prominent when the individual is under mental stress or physically tired.


• Laryngeal dystonia - This is a focal (just one part of the body is affected), late-onset type of dystonia. The muscles in the voice box (larynx) spasm. The larynx muscle spasming may be inwards or outwards.
  
  Patients may sound very quiet and breathy when they speak, or strangled - depending on which way the muscle spasm.
  
  Myoclonus dystonia - this is a segmental, late onset dystonia (occurs after 40 years of age, two or more body regions are affected). The arm, neck and torso muscles are affected. Patients with spasms may look as though they are receiving an electric shock (sudden, jerky movements).


• Onmandibular dystonia - this segmental, late-onset type of dystonia affects the jaw and mouth muscles. The patient's mouth can pull outwards and upwards.
  
  Some patient will only have symptoms when the muscles of the mouth and jaw are being used, while others may experience symptoms even at other times (when muscles are not in use). Often, patients with symptoms when their mouth and jaw muscles are not being used may experience relief when talking or chewing.
  
  Some patients may have dyphagia (problems swallowing).


• Writer's cramp - the patient experiences uncontrollable cramps and movements in the arm and wrist. It is a late-onset, focal type of dystonia. This is a task-specific dystonia, because most patients already to a lot of writing before onset of symptoms appear.


• Other task-specific dystonias:
  
  
  • Musician's cramp
  • Typist's cramp
  • Golfer's cramp


• Generalized dystonia - patients are usually children at the beginning of puberty. Hence, it is an early-onset dystonia. Symptoms generally are felt in one of the limbs, and eventually spread to other parts of the body.
  
  The patient may experience..
  
  
  • Muscle spasms
  • An abnormal, twisted posture, due to contractions and spasms in the limbs and torso
  • A limb (or foot) may turn inwards
  • Parts of the body may suddenly jerk rapidly


• Paroxysmal dystonia - muscle spasms and abnormal body movements only happen at specific moments; otherwise the patient has no symptoms at all (at other times). It is a rare type of dystonia.
  
  Signs of paroxysmal dystonia may resemble those of epilepsy during a seizure (fit). When symptoms come on suddenly, they are known as an attack. Only the muscles are affected during an attack. The patient does not lose consciousness, and will be aware of his/her surroundings, unlike a patient with epilepsy. An attack can last for just a few minutes; and in some cases may persist for several hours. The following triggers may bring on an attack:
  
  
  • Mental stress
  • Tiredness (fatigue)
  • Consuming alcoholic beverages
  • Consuming coffee
  • A sudden movement

What are the causes of dystonia?

Causes of primary dystonia (when no underlying cause is identified) - experts say that a problem with the basal ganglia is most likely associated with primary dystonia symptoms.

According to Medilexicon's medical dictionary, the basal ganglia is "originally, all the large masses of gray matter at the base of the cerebral hemisphere; as currently used, the striate body (caudate and lentiform nuclei); cell groups functionally associated with the striate body, such as the subthalamic nucleus and substantia nigra are frequently, but incorrectly, grouped as part of the basal nuclei/ganglia."

Put more simply, the basal ganglia is a region consisting of 3 clusters of neurons, called the nucleus, putamen and globus pallidus, found at the base of the brain. They are responsible for involuntary movements, such as tremors, athetosis (Involuntary writhing movements particularly of the arms and hands), and chorea (incessant rapid complex body movements that look well coordinated and purposeful but are, in fact, involuntary). In order to move muscles, special messenger-chemicals, called neurotransmitters are released.

Experts believe that not enough neurotransmitters are produced in the basal ganglia, resulting in primary dystonia symptoms. It is also possible that enough is produced, but not the right type for proper muscle function.

Experts also say that inherited faulty genes cause the basal ganglia not to develop properly, resulting in early-onset dystonia. Generalized dystonia, dopa-responsive dystonia, and paroxysmal dystonia, plus another 9 types are all linked to faulty genes. A child with one parent who has the faulty gene has a 50% chance of developing dystonia (autosomal dominant gene).

• Causes of late-onset primary dystonia are unknown.


• Causes of secondary dystonia - this type of dystonia is caused by its underlying cause, which can be one, or a combination of various conditions and diseases. For example:
  
  
  • Brain tumors
  • Carbon monoxide or heavy metal poisoning
  • Oxygen deprivation
  • Cerebral palsy
  • Huntington's disease
  • MS (multiple sclerosis)
  • Parkinson's disease
  • Some infections, such as encephalitis, TB (tuberculosis) or HIV
  • Some medications, such as those taken by patients with epilepsy
  • Stroke
  • Traumatic brain or spine injury
  • Wilson's disease

How is dystonia diagnosed?

A visual examination of the physical signs contributes greatly to a firm diagnosis of dystonia. However, the doctor will need to carry out some tests and ask targeted question in order to determine whether the patient has primary or secondary (has an underlying condition/disease) dystonia.

The following tests and procedures help determine what type of dystonia the patient has:

• Finding out about the patient's medical and family history - the doctor, usually a neurologist, may ask the patient whether he/she has recently had a head injury, or whether any close relatives also have symptoms.


• Blood/urine tests - the aim here is to determine whether there are any toxins, infections, and checking organ function (such as the liver).


• Genetic test - the patient's DNA can be collected from a blood test to determine whether there are any faulty (abnormal, mutated) genes linked to some kinds of dystonia. Genetic testing may also determine or rule out such genetic conditions as Huntington's disease.


• MRI (magnetic resonance imaging) scan - this type of scan may reveal brain damage, or a tumor.


• Levodopa - this dopamine medication may help confirm early-onset dystonia. If symptoms improve rapidly after taking levodopa, the doctor will most likely diagnose early-onset dystonia.

What are the treatment options for dystonia?

Medications

• Levodopa - patients diagnosed with dopa-responsive dystonia (early onset) will be prescribed levodopa treatment. This effective medication raises levels of dopamine - a brain neurotransmitter. Patients may initially experience nausea, which should ease and disappear after the body gets used to the drug.
  
  The following rare side effects are also possible:
  
  
  • A compulsion to gamble
  • Anxiety, confusion and disorientation
  • Diarrhea
  • Dizziness, especially when standing up
  • Lack of appetite
  • Vomiting
  
  Any patient who experiences these rare side-effects should tell his/her doctor; in most cases the dosage will be altered.
  
  Levodopa is not generally recommended for either pregnant women, women who are trying to become pregnant, or breastfeeding mothers.


• Botulinum toxin - this powerful poison, which is safe when administered in very small doses, is often used as a first-line treatment for most other types of dystonia. It prevents specific neurotransmitters from reaching the affected muscles, thus preventing spasms.
  
  Botulinum toxin is administered by injection. One dose usually lasts about three months. Patients may feel some initial (temporary) pain at the injection site.
  
  The following side effects are also possible:
  
  
  • Swallowing difficulties when the injection is administered in the neck.
  • Drooping eyes, and/or double vision when the injection is administered around the eyes.
  • Altered voice when the injection is administered in the vocal cord.
  
  In most cases, these side-effects do not last more than a week.


• Anticholinergics - this medication blocks the release of acetylcholine, a neurotransmitter known to cause muscle spasms in some types of dystonia. Anticholinergics may not always work.
  
  Possible side-effects include:
  
  
  • Blurred vision
  • Confusion
  • Constipation
  • Dry mouth
  • Memory problems
  • Urinating difficulties


• Muscle relaxants - this type of medication is usually prescribed if other treatment have not been effective. They raise the levels of GABA (gamma-aminobutyric acid), a neurotransmitter which relaxes muscles. Examples of muscle relaxants include diazepam and clonazepam. The medication is administered either orally or by injection.
  
  Possible side-effects may include:
  
  
  • Fatigue
  • Muscle weakness
  • Dizziness
  • Coordination problems
  
  As soon as the body gets used to the medication the above-mentioned symptoms usually disappear. Patients should never stop taking muscle relaxants cold-turkey (suddenly). Make sure you get off them under your doctor's supervision and instructions.

Physical therapy (UK: physiotherapy)

• Sensory tricks - if the affected body part is touched, or a nearby body part, symptoms may improve considerably. Patients with cervical dystonia may find that if they touch the back of their head or the side of their face, symptoms improve or go away completely.
  
  Splints and braces may sometimes be used as part of a sensory trick therapy.
  
  A physical therapist can also help the patient improve their posture. Good posture helps protect and strengthen muscles and tissues. Good posture may be achieved with an exercise program, and/or the use of braces.

Surgery If other therapies have not been effective, the doctor may recommend surgery. Surgical procedures may include:

• Selective peripheral denervation - sometimes used for patients with cervical dystonia. The surgeon makes an incision in the patient's neck before cutting some of the nerve endings that are connected to affected muscles. After surgery the patient will most likely experience some loss of feeling in their neck. Complications are rare; if they do occur they may include:
  
  
  • Infection in the neck
  • Swelling of the neck (short-term)
  • Pins and needles in the neck
  • Sudden burst of neck pain


• Deep brain stimulation - a type of brain surgery. Small holes are drilled into the skull. Tiny electrodes are threaded through the holes and placed in the globus pallidus, part of the basal ganglia.
  
  A small pulse generator is connected to the electrodes. The pulse generator is implanted under the skin, usually in the chest or lower abdomen. The pulse generator emits signals to the globus pallidus, which help block the abnormal nerve impulses produced by the basal ganglia.
  
  In rare occasions the pulse generator may cease working, or the electrodes can move out of the targeted area. In such cases the patient will have to undergo surgery again.
  
  There is not much information on the long-term beneficial or detrimental effects of deep brain stimulation, because it is a fairly new technique.
  
  Patients may have to keep coming back to see their doctor until the signals are adjusted for best results.
  
  Deep stimulation results take time, sometimes even months.

What are the possible complications of dystonia?

• The patient's mobility and ability to carry out daily activities may be affected if symptoms are severe.


• Individuals with generalized dystonia may be stigmatized because of their disordered movement.


• A person with dystonia may also feel tired and pain after long periods of muscle movements, as if they had done a heavy workout.


• Coping with mobility problems, being stigmatized or fatigue may lead to frustration, anxiety, and possibly depression.

Written by Christian Nordqvist


Copyright: Medical News Today
Not to be reproduced without permission of Medical News Today

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