Dystonia - What is Dystonia?

Dystonia is a neurological movement disorder, in which sustained muscle contractions cause twisting and repetitive movements or abnormal postures.

The disorder may be hereditary or caused by other factors such as birth-related or other physical trauma, infection, poisoning (e.g., lead poisoning) or reaction to pharmaceutical drugs, particularly neuroleptics.

Types of dystonia

  • Generalized
  • Focal
  • Segmental
  • Intermediate
  • Acute Dystonic Reaction

Generalized dystonias

  • Normal birth history and milestones
  • Autosomal dominant
  • childhood onset
  • starts in lower limbs and spreads upwards
  • also known as "idiopathic torsion dystonia" (old terminology "dystonia musculrum deformans")

Focal dystonias

These are the most common dystonias and tend to be classified as follows:

Name Location Description
Cervical dystonia (spasmodic torticollis) muscles of the neck Causes the head to rotate to one side, to pull down towards the chest, or back, or a combination of these postures.
Blepharospasm muscles around the eyes The sufferer experiences rapid blinking of the eyes or even their forced closure causing effective blindness.
Oculogyric crisis muscles of eye and head An extreme and sustained (usually) upward deviation of the eyes often with convergence causing diplopia. It is frequently associated with backwards and lateral flexion of the neck and either widely opened mouth or jaw clenching. Frequently a result of antiemetics such as the neuroleptics (e.g., prochlorperazine) or metoclopramide.
Oromandibular dystonia muscles of the jaw and muscles of tongue Causes distortions of the mouth and tongue.
Spasmodic dysphonia/Laryngeal dystonia muscles of larynx Causes the voice to sound broken or reducing it to a whisper.
Focal hand dystonia (also known as musician's or writer's cramp). single muscle or small group of muscles in the hand It interferes with activities such as writing or playing a musical instrument by causing involuntary muscular contractions. The condition is sometimes "task-specific," meaning that it is generally only apparent during certain activities. Focal hand dystonia is neurological in origin, and is not due to normal fatigue. The loss of precise muscle control and continuous unintentional movement results in painful cramping and abnormal positioning that makes continued use of the affected body parts impossible.

The combination of blepharospasmodic contractions and oromandibular dystonia is called cranial dystonia or Meige's syndrome.

Segmental dystonias

Segmental dystonias affect two adjoining parts of the body:

  • Hemidystonia affects an arm and a leg on one side of the body.
  • Multifocal dystonia affects many different parts of the body.
  • Generalized dystonia affects most of the body, frequently involving the legs and back.

Genetic / primary

Name OMIM Gene Locus Alt Name
DYT1 (or EOTD)   DYT1 9q34 early-onset torsion dystonia
DYT2   unknown unknown autosomal recessive torsion dystonia
DYT3   TAF1 Xq13 X-linked torsion dystonia
DYT4   unknown unknown autosomal dominant torsion dystonia
DYT5 (or DRD)   GCH1 14q22.1-q22.2 Dopamine-responsive dystonia
DYT6   THAP1 8p11.21  
DYT7   unknown 18p Primary cervical dystonia
DYT8 (or PNKD1)   MR1 2q35 paroxysmal nonkinesigenic dyskinesia 1
DYT9   possibly KCNA3 1p episodic choreoathetosis/spasticity
DYT10 (or EKD1)   unknown 16p11.2-q12.1 episodic kinesigenic dyskinesia 1
DYT11   SGCE 7q21 Myoclonic dystonia
DYT12   ATP1A3 19q12-q13.2  
DYT13   unknown, near D1S2667 1p36.32-p36.13  
DYT14 See DYT5      
DYT15   unknown 18p11 Myoclonic dystonia
DYT16   PRKRA 2q31.3  
DYT17   unknown, near D20S107 20p11.2-q13.12  
DYT18   SLC2A1 1p35-p31.3  
DYT19 (or EKD2)   unknown 16q13-q22.1 episodic kinesigenic dyskinesia 2
DYT20 (or PNKD2)   unknown 2q31 paroxysmal nonkinesigenic dyskinesia 2

There is a group called myoclonus dystonia or myoclonic dystonia, where some cases are hereditary and have been associated with a missense mutation in the dopamine-D2 receptor. Some of these cases have responded remarkably to alcohol.

Further Reading

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