Dystonia Classification & Definition

Dystonia is defined as a movement disorder characterized by sustained or intermittent muscle contractions causing abnormal, often repetitive, movements, postures, or both. Dystonic movements are typically patterned, twisting, and may be tremulous. Dystonia is often initiated or worsened by voluntary action and associated with overflow muscle activation.

Improved definition and classification of dystonia

In 2013 Prof. Alberto Albanese et al. proposed this new and improved definition and classification of dystonia. The main aim of the new classification is to improve the clinical characteristics of dystonia and organize current knowledge regarding the ethology. Two axes were developed: Axis 1 for clinical characteristics and Axis 2 for aetiology. Additionally, the term “primary” and “secondary” dystonia is no longer used and has been replaced by isolated dystonia and combined dystonia.

Axis 1 – Clinical characteristic:

  1. Age of onset

    • Infancy (birth to 2 years)
    • Childhood (3–12 years)
    • Adolescence (13–20 years)
    • Early adulthood (21–40 years)
    • Late adulthood (>40 years)

  1. Body distribution

    • FOCAL – Only one body region is affected (e.g. blepharospasm, oromandibular dystonia, cervical dystonia, laryngeal dystonia, and writer’s cramp).
    • SEGMENTAL – Two or more contiguous body regions are affected( e.g. cranial dystonia)
    • MULTIFOCAL – Two noncontiguous or more body regions are involved.
    • GENERALIZED – The trunk and at least 2 other sites are involved.
    • HEMIDYSTONIA – More body regions restricted to one body side are involved (e.g. brain lesions)

  1. Temporal pattern ( e.g. Disease course and Variability)

  2. Associated features (isolated dystonia or combined with another movement disorder)

Axis 2 – Aetiology

  1. Nervous system pathology ( neurodegeneration/structural  lesion/ No evidence of degeneration or structural lesion)

  2. Inherited or acquired

  3. Idiopathic (sporadic/familial)