Action for Dystonia, Diagnosis, Education & Research

A.D.D.E.R.

Introduction

This paper has been published by A.D.D.E.R. to assist people who want to know what Dystonia is. It describes how the disease can affect people and how treatment may be provided. The information is based on the Epidemiological Survey of Dystonia (ESD), which arose from research carried out in North East England between 1993 and 1999. The database continues to be maintained and currently, there are over 1,600 people registered in the ESD.

Definition

Dystonia has been defined as a, previously little known, neurological disease of the body’s central nervous system and consists of a group of related movement disorders, characterised by involuntary and often painful, prolonged spasms of muscle contractions. It has also been classically defined as "a syndrome of sustained muscle contractions, frequently causing twisting and repetitive movements, or abnormal postures."

It can affect a single part of the body, or the whole body, or any mid-way position between these two extremes. Despite this neurological disorder being named by Oppenheim in 1911, relatively little research had been undertaken until recently. The ESD was the first comprehensive and lengthy study of the disease, undertaken within a specified population, anywhere in the world.

Until 1996, Dystonia was usually classified, according to criteria originating from the Ad Hoc Committee of the Dystonia Medical Research Foundation, as follows: -

(1) By Cause 

        (1.1) Idiopathic (familial and sporadic) or Primary Dystonia, generally with an unknown cause.

         (1.2) Symptomatic or Secondary Dystonia, with a known or assumed cause. 

(2) By Age at Onset  

         (2.1) Childhood – onset : less than or up to 12 years.

         (2.2) Adolescent – onset: 13 – 20 years.

         (2.3) Adult – onset : greater than 20 years.

 (3) By Distribution  

         (3.1) Focal – affects a single part of the body.

         (3.2) Segmental – affects two or more connecting parts.

         (3.3) Multifocal – affects two or more non-contiguous parts.

         (3.4) Hemidystonia – affects an arm and leg only on the same side of the body.

         (3.5) Generalised – as Segmental, together with at least one leg.

The new aetiological (causal) classification results from our ever-improving understanding of this disorder. Changes emerged from an International Symposium in Florida during 1996 when the aetiological classification of Dystonia was enlarged. This reflected the recent discoveries in the genetics of dystonia and the conclusion that more than genes can cause idiopathic dystonia. Dystonia can now be divided into four main causal classifications, each relating to specific other recognised entities that appear distinct (see table below). These classifications may be enlarged in future as further genetic, pathological and biochemical advances are made.

The distribution of the dystonias has not changed but these need to be described in greater detail in order to promote this as a neurological condition. Patients often know the name of say the focal dystonia that they have without making the neurological link. The following table shows the distribution of the focal dystonias and the names given to the various conditions.

The Segmental Dystonias (affecting two or more connecting parts) have a number of different terminologies to describe various different forms of the disorder as shown below.

Cranial Dystonia can be sub-divided and is often given other names e.g.,

The Hemi-dystonias affect and arm and leg only, on the same side of the body.

Multi-focal Dystonia affects two or more non-contiguous parts, e.g. a left arm and a right leg.

Generalised Dystonia can be defined as a combination of Segmental Crural Dystonia and any other segment of the body. Another way is to describe it is at least one leg +/- the trunk and another segment such as the head and the neck.

Further Statistics

Darlington, a typical North East town, has a population of 100,000 people. It has the highest concentration of dystonia, anywhere in the world, with approximately 48 people within the postal codes DL1, DL2, and DL3.

The following table shows where the first 1,000 people with dystonia, registered on the database, live within the region.