Torsion dystonia (dystonia musculorum deformans)

Published on 02/04/2015 by admin

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Last modified 22/04/2025

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92 Torsion dystonia (dystonia musculorum deformans)

Instruction

Look at this patient.

Diagnosis

This patient has torsion dystonia (lesion), which may be a result of birth anoxia (aetiology), and is confined to a wheelchair because of the disability (functional status).

Questions

What do you understand by the term dystonia?

It implies a movement caused by a prolonged muscular contraction when a part of the body is thrown into spasm. Dystonia is defined as a movement disorder that causes sustained muscle contractions, repetitive twisting movements, and abnormal postures of the trunk, neck, face, or arms and legs (Marsden CD, Fahn S (eds.) Movement Disorders 2. London: Butterworths, 1987, pp. 332–58).

Advanced-level questions

What is the inheritance of dystonia?

Dystonia loci DYT1 through DYT13 include autosomal dominant, autosomal recessive, and X-linked causes of primary dystonia and dystonia-plus syndromes.

What are the other causes of dystonia?

• Birth anoxia (abnormal movements develop before the age of 5 years; often associated with a history of seizures and mental disability)

• Wilson’s disease, Huntington disease or parkinsonism

How would you treat such patients?

• Drugs: patients respond poorly to drugs. Occasionally helpful medications include diazepam, levodopa, amantidine, carbamezapine, tetrabenazine, phenothiazines and haloperidol.

• Stereotactic thalamotomy may be useful in predominantly unilateral dystonia.

What are the abnormal postures in dystonia?

• Cervical dystonia: combined head rotation and backward head deviation

• Blepharospasm: involuntary eye closure with reactive lower facial grimacing

• Oromandibular dystonia: involuntary jaw opening

• Lower-limb dystonia: involuntary ankle inversion and toe flexion

• Upper-limb dystonia (writers cramp): flexion dystonia of the wrist and digits while the patient is writing.

What is dopa-responsive dystonia?

Dopa-responsive dystonia is an inherited condition (now classified as DYT5) that results in dopamine deficiency in the basal ganglia, unaccompanied by neuronal degeneration. An important feature of this disorder is that the neurologic function is substantially improved in a sustained manner by means of orally administered dopaminergic therapy. Two biochemical pathway defects have been described in patients with dopa-responsive dystonia: autosomal dominant guanosine triphosphate cyclohydrolase 1 (GTPCH1) deficiency and autosomal recessive tyrosine hydroxylase deficiency. GTPCH1 is the rate-limiting enzyme in the synthesis of tetrahydrobiopterin, which has a central role as cofactor in the metabolic pathways, including the synthesis of the biogenic amine dopamine; in the hepatic metabolism of phenylalanine to tyrosine; and in the production of the serotonin precursor 5-hydroxytryptophan. The gene that encodes the 32 kDa GTPCH1 protein, GCH1, is located on chromosome 14q22.1. Because of incomplete penetrance and apparently high rate of sporadic mutation, many patients may have no family history of dystonia.

Further reading

Tarsy D, Simon DK. Dystonia. N Engl J Med. 2006;355:818-829. (classic article)

Hermann Oppenheim (1858–1919), a German neurologist, coined the term dystonia in 1911 to describe a disorder causing variable muscle tone and recurrent muscle spasm.

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