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For further information, see CMDT Part 26-14: Movement Disorders
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Essentials of Diagnosis
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Dystonic movements and postures
No other neurologic signs
Normal birth and developmental history
Investigations (including CT scan or MRI) reveal no cause of dystonia
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General Considerations
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May occur sporadically or on a hereditary basis, with autosomal dominant, autosomal recessive, and X-linked recessive modes of transmission
One responsible gene is located at 9q34 (and has been named DYT1)
Involves a unique mutation consisting of a GAG deletion in the major dominantly inherited disorder and maps to the long arm of the X chromosome in the X-linked recessive disorder
The gene responsible for the autosomal recessive disorder is unknown
Symptoms may begin in childhood or later and persist throughout life
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Onset of abnormal movements and postures in a patient with
A normal birth and developmental history
No relevant past medical illness
No other neurologic signs
Dystonic movements of the head and neck
The limbs may also adopt abnormal but characteristic postures
The age at onset influences both the clinical findings and the prognosis
Childhood onset
A family history of the disorder is usual
Initial symptoms commonly in the legs
Progression is likely until there is severe disability from generalized dystonia
Adult onset
A positive family history is unlikely
Initial symptoms are often in the arms or axial structures
Severe disability does not usually occur, although generalized dystonia may ultimately develop in some patients
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Differential Diagnosis
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Idiopathic torsion dystonia usually responds poorly to drugs
Levodopa, diazepam, baclofen, carbamazepine, amantadine, or anticholinergic medication such as trihexyphenidyl or benztropine (in high dosage) occasionally helpful
If not, a trial of treatment with tetrabenazine, phenothiazines, or haloperidol may be worthwhile
In each case, the dose has to be individualized, depending on response and tolerance
However, the doses of tetrabenazine, phenothiazines, or haloperidol required for benefit usually lead to mild parkinsonism
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Therapeutic Procedures
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