TORSION DYSTONIA DISORDER

       TORSION DYSTONIA DISORDER

    Dystonia
    Early-onset Torsion Dystonia
         -Disease symptoms
         -Inheritance

Dystonia is a disorder characterized by involuntary spasms and muscle contractions that induce abnormal movements and postures. Dystonia may affect only one part of the body, such as the neck or arm, or can affect the whole body. There are many different types of dystonia. Primary or idiopathic dystonia have no known organic lesions and secondary dystonia arises from an insult to the basal ganglia of the central nervous system. Generalized dystonia (affects a wide range of body areas) usually occurs in childhood and most often affects the limbs and feet. The most common type is Torsion dystonia, which is inherited and can leave individuals seriously disabled and confined to a wheelchair. This type of dystonia will be the main focus for the rest of this discussion. Focal dystonias (affects specific body parts) usually occur later in life (40s to 50s) and an individual may suffer from more than one type (Howell, 1997). Some of the most common forms of focal dystonias are:


                    Characteristics of different types of dystonia

Cervical dystonia (spasmodic torticollis) is the most common of the focal dystonias. It affects the muscles in the neck, head, and spine that causes the head to turn to one side.

   Blepharospasm is the second most common focal dystonia. It causes involuntary contraction of the eyelids and can hold them closed for indefinite periods of time.

   Oromandibular dystonia affects the jaw, lips, and/or the tongue causing the jaw to be held open or clamped shut. This makes eating, swallowing, or speaking very difficult.

   Spasmodic dysphonia affects muscles that control the vocal cords resulting in speech that wavers, is halting, or is reduced to a breathless whisper.

    Writer's Cramp (occupational dystonia) affects the muscles of the hand and sometimes the forearm and are triggered when the sufferer attempts to write or perform other fine hand functions.

   Orofacial-Buccal dystonia (Meige's or Brueghal's Syndrome) is a combination of blepharospasm and oromandibular dystonia.

This information and related web sites are found at the Dystonia Dialogue web document.

Early-onset torsion dystonia represents the most severe and most common form of hereditary dystonia. Symptoms of this disorder will usually surface in childhood before the age of 12. These symptoms typically start in one part of the body, usually in the arm or leg, and eventually spread to the rest of the body within about five years. Children with this disorder are unable to perform simple motor tasks and are usually confined to a wheel chair. It has been shown to be more common than disorders such as Huntington's disease and amyotrophic lateral sclerosis.

      Inheritance is simple for early-onset torsion dystonia. This dystonia appears when a person is heterozygous, having one copy of a mutated gene and one copy of a normal gene. Thus, this disease follows an autosomal dominant mode of inheritance. This disease also has a 30-40% penetrance, which means that 30 to 40 percent of people who have a mutated gene develop symptoms. This disorder has been estimated to occur at rates ~5 to 10 fold greater in the Ashkenazi Jewish community, as compared to non-Jewish and non-Ashkenazi populations. Researchers believe that dystonia may be caused by a breakdown of the dopamine system in the basal ganglia, which is a collection of structures in the brain that controls movement. Dopamine is a neurotransmitter in the basal ganglia and malfunctioning of this system is responsible for many movement disorders such as Parkinson's disease (Ozelius... et al., 1997).

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