Classifications of dystonia

Classifications of dystonia

A new basis for classifying the dystonias has been proposed on a consensus achieved and agreed by world experts in dystonia (Albanese A, et al. 2013)

 

The new classification is largely compatible with previous schemes and overcomes earlier terminological inconsistencies. The first axis (clinical features) is a clinical description that supports clinical diagnostic assessment. The second axis is structured as a database of different etiologies. By combining the two axes together each patient can be described in detail, taking into account clinical characteristics and etiological descriptors

 

 Axis 1 Clinical Features

Age of onset

  • Infancy (0-2 years)
  • Childhood (3-12 years)
  • Adolescence (13-20 years)
  • Early adulthood (21-40 years)
  • Late adulthood  (40 years and older)

 

Body distribution
Any body region may be affected by dystonia. Classification is done by the number of specific areas of the body that are affected.

 

Focal Dystonia – most frequent type of dystonia affects just a  specific body part

 

Segmental Dystonia – affects two or more connected body areas  (for example, the neck, shoulder and arm)

 

Multifocal –  affects two or more areas in different parts of the body
(for example the eyes and the vocal cords)

 

Generalised Dystonia – refers to dystonia that may affect limbs, trunk and other major areas simultaneously

 

Hemidystonia – only affects muscles on one side of the body

 

Temporal pattern
Temporal pattern helps to distinguish between dystonia that becomes progressively worse or remains unchanged (static). It also refers to the variability in disease expression in relation to other factors such as external triggers or voluntary actions.

Temporal patterns can be divided in four subgroups:
  • Persistent – symptoms persists throughout the day without fluctuation
  • Task-specific – dystonia occurs only during  a specific action or task   (such as writing or playing a musical instrument)
  • Diurnal –  dystonia fluctuates in severity at certain times throughout  the day and symptoms often lessen during the night
  • Paroxysmal – in which a sudden, temporary episode of dystonia occurs often as the result of a specific trigger

 

Dystonia can also be classified by whether or not dystonia occurs along with another movement disorder.

Associated features

Isolated dystonia when dystonia is the only motor feature (with the exception of tremor)

Combined dystonia –  when another movement disorder such as parkinsonism or myoclonus is also present

 

Axial II Etiology

Nervous system pathology – refers to whether degenerative changes or structural damage is present in the nervous system

 

Inherited or Acquired

Inherited – linked to a known gene locus or gene defect

Acquired (dystonia due to a known specific cause) – dystonia resulted from birth injury, stroke, brain tumours, certain infections, drugs/toxins, vascular, neoplastic, brain injury, psychogenic

 

Idiopathic – dystonia may be inherited or occur for unknown reasons

  • Sporadic
  • Familial