In 2013, a new classification of dystonia based in an international panel of experts was
published in the journal of Movement Disorders11 Albanese A, Bhatia K, Bressman SB, Delong MR, Fahn S, Fung VS et al.
Phenomenology and classification of dystonia: a consensus update. Mov Disord.
2013;28(7):863-73. http://dx.doi.org/10.1002/mds.25475
https://doi.org/10.1002/mds.25475...
. This consensus provided an update on definition, phenomenology and
classification of dystonia. By the new definition “dystonia is 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”
11 Albanese A, Bhatia K, Bressman SB, Delong MR, Fahn S, Fung VS et al.
Phenomenology and classification of dystonia: a consensus update. Mov Disord.
2013;28(7):863-73. http://dx.doi.org/10.1002/mds.25475
https://doi.org/10.1002/mds.25475...
. This new classification
encompasses two axis, namely “clinical characteristics” (Axis 1) and “etiology” (Axis 2). The
first axis focuses on clinical manifestations of dystonia and includes the four following
characteristics: age at onset, body region affected, temporal aspects, and any associated
clinical manifestations. The second axis focuses on etiology with two dimensions for
inheritance and underlying neuropathology. To clinical purpose these two axis should never be
viewed independently. Instead the goal of delineating the clinical phenomenology (Axis I) is
to build a syndromic pattern that will help in dystonia etiology22 Jinnah HA, Albanese A. The new classification system for the dystonias: why
was it needed and how was it developed? Mov Disord Clin Pract (Hoboken). 2014;1(4):280-4.
http://dx.doi.org/10.1002/mdc3.12100
https://doi.org/10.1002/mdc3.12100...
.Regarding the age of onset earlier dystonia classification was based
in two groups (early and late onset) with an age cutoff of 26 years. This was based in a study
that divided at 26 years the age on discriminating patients with DYT133 Bressman SB, Sabatti C, Raymond D, Leon D, Klein C, Kramer PL et al. The
DYT1 phenotype and guidelines for diagnostic testing. Neurology.
2000;54(9):1746-52.. This age discriminator was obviously not suitable for
application to all dystonias. The new classification system has a spectrum of onset from
pediatric to adult. That include at age onset: infancy (birth to 2 years); childhood (3-12
years); adolescence (13-20 years); early adulthood (21-40 years); late adulthood (40 years and
older). The age at onset may give important clues to the underlying etiology22 Jinnah HA, Albanese A. The new classification system for the dystonias: why
was it needed and how was it developed? Mov Disord Clin Pract (Hoboken). 2014;1(4):280-4.
http://dx.doi.org/10.1002/mdc3.12100
https://doi.org/10.1002/mdc3.12100...
,44 Balint B, Bhatia KP. Dystonia: an update on phenomenology, classification,
pathogenesis and treatment. Curr Opin Neurol. 2014 Aug;27(4):468-76.
http://dx.doi.org/10.1097/WCO.0000000000000114
https://doi.org/10.1097/WCO.000000000000...
. Regarding the body distribution dystonia are described as focal,
segmental, multifocal, generalized (with or without leg involvement) or hemidystonia. The body
region affected has important value in guiding not only treatment decisions but also the
etiological diagnosis. Temporal aspects which features had not been considered in the previous
classification have been included. They includes manner of onset (acute or insidious),
short-term variations in symptoms (diurnal, intermittent, or action induced), and longer-term
variations in overall severity (static or progressive). Temporal aspects have important
implications for diagnostic testing. For instance, diurnal patterns are suggestive of
dopa-responsive dystonia, and intermittent patterns suggest one of the paroxysmal dyskinesia.
Rapid-onset dystonia are less-common conditions but when present we should considered dystonia
parkinsonism or glutaric aciduria22 Jinnah HA, Albanese A. The new classification system for the dystonias: why
was it needed and how was it developed? Mov Disord Clin Pract (Hoboken). 2014;1(4):280-4.
http://dx.doi.org/10.1002/mdc3.12100
https://doi.org/10.1002/mdc3.12100...
.Regarding
associated clinical manifestation dystonia the new terminology uses “isolated dystonia” to
describe cases in which dystonia is the only motor feature apart from tremor. The previously
called dystonia plus syndromes (e.g. myoclonus-dystonia) are now called “combined dystonia”,
which refer to phenomenology rather than etiology. The Axis 2 that is based in presumed
etiology are classified according the nervous system pathology (evidence of
degeneration/structural lesions/neither or both) and heritability (inherited or acquired).
Inherited dystonia can be sex linked or autosomal, dominant or recessive, or mitochondrial.
When an etiology is not defined, it is classified as idiopathic (sporadic or familial). The
commonly used primary and secondary terms are not used in the new classification. In fact,
these terms are confused once they have been used to mean different things22 Jinnah HA, Albanese A. The new classification system for the dystonias: why
was it needed and how was it developed? Mov Disord Clin Pract (Hoboken). 2014;1(4):280-4.
http://dx.doi.org/10.1002/mdc3.12100
https://doi.org/10.1002/mdc3.12100...
,44 Balint B, Bhatia KP. Dystonia: an update on phenomenology, classification,
pathogenesis and treatment. Curr Opin Neurol. 2014 Aug;27(4):468-76.
http://dx.doi.org/10.1097/WCO.0000000000000114
https://doi.org/10.1097/WCO.000000000000...
. Primary dystonia has already been used either to refer to idiopathic
dystonia or to nomine phenotypically isolated forms of dystonia, regardless of etiology. By
these reasons, the term “primary” should be abandoned22 Jinnah HA, Albanese A. The new classification system for the dystonias: why
was it needed and how was it developed? Mov Disord Clin Pract (Hoboken). 2014;1(4):280-4.
http://dx.doi.org/10.1002/mdc3.12100
https://doi.org/10.1002/mdc3.12100...
. The term heredodegenerative that was used based on etiology was also
excluded. This term included an enormous list of conditions that was not very practical to
organize dystonia etiology. Furthermore, some disorders are hereditary, but are not
degenerative. On the other hands, some disorders are degenerative but not hereditary22 Jinnah HA, Albanese A. The new classification system for the dystonias: why
was it needed and how was it developed? Mov Disord Clin Pract (Hoboken). 2014;1(4):280-4.
http://dx.doi.org/10.1002/mdc3.12100
https://doi.org/10.1002/mdc3.12100...
. New genetic technologies has markedly
accelerated the process of genes discovery related to dystonias55 Lohmann K, Klein C. Genetics of dystonia: What's known? What's new? What's
next? Mov Disord. 2013 Jun 15;28(7):899-905.
http://dx.doi.org/10.1002/mds.25536
https://doi.org/10.1002/mds.25536...
. In this edition of Arquivos de Neuro-Psiquiatria,
Camargo et al.66 Camargo CH, Camargos ST, Cardoso FE, Teive HG. The genetics of the
dystonias: a review based on the new classification of the dystonias. Arq
Neuro-Psiquiatria. 2015;73(4):XX-XX., present a review of
genetics of dystonias based on the new classification. The authors present the inherit
dystonias according to the clinical aspects of the new classification such as age at onset, if
isolated or combined, and intermittent patterns. The main clinical aspects of childhood-onset
and adolescent-onset isolated dystonias (DYT 1, 2, 6, 13, 17), adult-onset isolated dystonias
(DYT 7, 21, 23, 24, 25), dystonias combined with parkinsonism (DYT 3, 5, 12, 16), dystonias
combined with myoclonus and chorea (DYT 4, 11, 15) and combined paroxysmal dystonia (DYT 8,
10, 18, 19, 20) were reviewed by the authors. With the advances in genetic technologies such
as exome and whole-genome, sequencing new genes underlying dystonia will be discovered55 Lohmann K, Klein C. Genetics of dystonia: What's known? What's new? What's
next? Mov Disord. 2013 Jun 15;28(7):899-905.
http://dx.doi.org/10.1002/mds.25536
https://doi.org/10.1002/mds.25536...
.Certainly idiopathic dystonia types will be
reclassified in inherited forms once new genes will be recognized. However, phenotypic
dystonia classification will be always important to recognize particular forms of dystonia and
to conduct correct diagnostic and therapeutic strategies.
References
-
1Albanese A, Bhatia K, Bressman SB, Delong MR, Fahn S, Fung VS et al. Phenomenology and classification of dystonia: a consensus update. Mov Disord. 2013;28(7):863-73. http://dx.doi.org/10.1002/mds.25475
» https://doi.org/10.1002/mds.25475 -
2Jinnah HA, Albanese A. The new classification system for the dystonias: why was it needed and how was it developed? Mov Disord Clin Pract (Hoboken). 2014;1(4):280-4. http://dx.doi.org/10.1002/mdc3.12100
» https://doi.org/10.1002/mdc3.12100 -
3Bressman SB, Sabatti C, Raymond D, Leon D, Klein C, Kramer PL et al. The DYT1 phenotype and guidelines for diagnostic testing. Neurology. 2000;54(9):1746-52.
-
4Balint B, Bhatia KP. Dystonia: an update on phenomenology, classification, pathogenesis and treatment. Curr Opin Neurol. 2014 Aug;27(4):468-76. http://dx.doi.org/10.1097/WCO.0000000000000114
» https://doi.org/10.1097/WCO.0000000000000114 -
5Lohmann K, Klein C. Genetics of dystonia: What's known? What's new? What's next? Mov Disord. 2013 Jun 15;28(7):899-905. http://dx.doi.org/10.1002/mds.25536
» https://doi.org/10.1002/mds.25536 -
6Camargo CH, Camargos ST, Cardoso FE, Teive HG. The genetics of the dystonias: a review based on the new classification of the dystonias. Arq Neuro-Psiquiatria. 2015;73(4):XX-XX.
Publication Dates
-
Publication in this collection
Apr 2015
History
-
Received
20 Mar 2015 -
Accepted
27 Mar 2015