Dystonia

Dystonia can be classified by three main factors:

• The age at which symptoms develop;

• The areas of the body affected; and

• The underlying cause.

The chance that dystonia will affect multiple body parts is generally linked to the age of onset. The younger one is at onset, the greater the chance that symptoms will spread. Conversely, the older one is at onset, the more likely that the disorder will remain more moderate.

• Childhood onset – 0 to age 12

• Adolescent onset – age 13 to 20

• Adult onset – older than age 20

Focal Dystonia:
Focal dystonia is limited to one area of the body and can affect the neck (cervical dystonia or spasmodic torticollis), eyes (blepharospasm), jaw/mouth/lower face (oromandibular dystonia), vocal cords (laryngeal dystonia) or arms/legs (limb dystonia). Other less common types of focal dystonia can cause unusual stretching, bending or twisting of the trunk (truncal dystonia) or sustained contractions and involuntary, writhing movements of the abdominal wall (abdominal wall dystonia).

Focal dystonia more commonly affects people in their 40s and 50s and is frequently referred to as adult-onset dystonia. Women are affected about three times more frequently than men. In general, focal dystonia can be classified as primary (idiopathic) and are not hereditary.

Segmental Dystonia:
Segmental dystonia affects two or more parts of the body.

A common form of segmental dystonia affects the eyelids, jaw, mouth and lower face.

Other types of dystonia include:
Multifocal, which involves two or more body parts distant from one another;

Hemidystonia, which affects half of the body; and

Generalized, which begins with leg involvement, but generally spreads to one or more additional regions of the body.

Primary (idiopathic):
To name a s primary dystonia all the secondary causes have to be ruled out. Most primary dystonias are variable, have adult onse, and are focal or segmental in nature. However, there are specific primary dystonias with childhood or adolescent onset that have been linked to genetic mutations.

The majority of early-onset primary dystonias, which may appear during childhood or early adulthood, are due to mutations of a gene known as DYT1.

In about 90 to 95 percent of cases, symptoms begin in a limb and then spread to other regions of the body. This form of dystonia has an average age of onset of 12 and seldom develops after age 29.

DYT6 dystonia is an autosomal dominant primary dystonia that has been mapped to chromosome 8. It is rarer than DYT1 dystonia.

Other familial primary Dystonia's identified are DYT7, DYT2, and DYT4, all of which have been noted in specific ethnic groups, primarily of European descent.

Secondary (symptomatic):
Secondary (symptomatic) results primarily from secondary causes.

These include Environmental, such as exposure to carbon monoxide, cyanide, manganese or methanol;

Brain conditions and diseases such as brain tumours, cerebral palsy, Parkinson’s disease, stroke, multiple sclerosis, hypoparathyroidism or vascular malformations; brain/spinal cord injuries; inflammatory, infectious or post infectious brain conditions; and specific medications.

Other rare types:
Dystonia-plus Syndromes:
Dystonia-plus syndromes include dopa-responsive dystonia (DRD) or Segawa syndrome, rapid-onset dystonia-parkinsonism (RDP) and myoclonus-dystonia.

Heredodegenerative Dystonia:
Heredodegenerative dystonia generally results from neurodegenerative disorders in which other neurological symptoms are present and in which heredity plays a role. These include numerous disorders such as certain X-linked recessive, autosomal dominant, autosomal recessive and/or parkinsonian syndromes. Included in this category: X-linked dystonia-parkinsonism (Lubag), Huntington's disease, Wilson's disease, neuroacanthocytosis, Rett’s syndrome, Parkinson's disease and juvenile parkinsonism.

Dystonia is sometimes misdiagnosed as stress, a stiff neck or a psychological disorder. Dystonia symptoms should not be confused with:

• Orthopedic conditions (for example, scoliosis and congenital torticollis)

• Muscle cramps

• Muscle contractures

• Essential tremor

• Tics

The intermittent character of the disorder may lead medical practitioners to conclude that a psychological disorder is either the primary cause or a contributing factor. Diagnosis is difficult because dystonia symptoms are similar to those of many other conditions and are so variable in nature.

Dystonia initially arises after specific movements or tasks but, in advanced stages, it may occur at rest. It usually affects the same group of muscles, thus causing a repetitive pattern of movements over time. It generally develops gradually, with localized symptoms suggesting the presence of the disorder.

Eye irritation, excessive sensitivity to bright light and increased blinking may be an indication of blepharospasm.

Subtle facial spasms, difficulty chewing or changes in speech cadence may indicate oromandibular dystonia.

Cramping of the hand during writing or fatigue during walking or other manual activities may indicate limb dystonia.

The disorder is usually not associated with pain, but it certainly may lead to pain in affected areas. Cervical dystonia can be particularly painful due to degeneration of the spine, irritation of nerve roots or frequent headaches. Limb dystonia may not cause pain initially but may become painful over time. Uncontrolled muscle movements may cause the joints to deteriorate, possibly leading to the onset of arthritis.

• Dystonic symptoms may worsen or occur only with specific tasks. For example, hand dystonia may be present only when writing or playing a musical instrument.

• Attempting a movement task on one side of the body my activate dystonia symptoms on the opposite side.

• Dystonic movements and postures may be temporarily relieved by a gentle touch or specific action called a sensory trick.

Early signs of dystonia often are mild, infrequent and linked to a specific activity. See your doctor if you are experiencing involuntary muscle contractions.

There is no definitive test for dystonia but doctors can make the diagnosis by learning about the symptoms and performing a neurological exam. Instead, the diagnosis rests in a physician's ability to observe the symptoms and obtain a thorough patient history Sometimes doctors use other tests such as a brain MRI to make sure something else is not causing the symptoms. The sub-specialist who has the training to diagnose and treat dystonia is a Movement disorders specialist, whom you need to consult and get an opinion.

For patients with early-onset dystonia or those with an affected relative, doctors may suggest genetic testing. Medical tests may be ordered to rule out other conditions or disorders.

The dystonia diagnostic process may include:

• Patient history

• Family history

• Physical examination to assess functioning of the nervous system

• Laboratory studies such as blood and urine tests, and analysis of cerebrospinal fluid

• Electrical recording techniques, such as electromyography (EMG) or electroencephalography (EEG)

• Genetic testing for inherited forms of dystonia

• Additional tests and screenings intended to rule out other conditions or disorders

There is no cure for dystonia and treatment is therefore directed at relieving symptoms.

There is a three-tiered approach to treating dystonia:

Botulinum toxin (botox) injections,
Several types of medication and
Surgery.
These may be used alone or in combination. Medications and botox can both help block the communication between the nerve and the muscle and may lessen abnormal movements and postures.

Botulinum toxin type A was developed in the 1980s. In 2001, the U.S. Food and Drug Administration approved botulinum toxin type B for treatment of cervical dystonia. Researchers created the new drug after some patients began developing resistance to the type A form. The type B drug has mild to moderate side effects such as dry mouth, dysphagia (difficulty swallowing) and indigestion.

Surgical treatment may be considered if medications and other treatments are not providing adequate relief, and if the symptoms negatively affect quality of life. Team consisting of Functional Neurosurgeon, movement disorder specialist, neurophysiologist will decide when to get surgical treatment. The mainstay of surgical treatment for dystonia is deep brain stimulation (DBS). During DBS surgery, a battery-powered stimulator similar to a pacemaker is implanted in the body and delivers electrical stimulation to the areas of the brain responsible for causing dystonia symptoms. The stimulation to the brain is adjusted by remote control to achieve the appropriate settings for each individual patient.

DBS has replaced other surgical techniques such as stereotactic thalamotomy, pallidotomy, and cervical rhizotomy because of its success and lower risk for side effects. The benefits of any surgery though should always be weighed carefully against its risks.