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Detailed information of IDIOPATHIC TORSION DYSTONIA
IDIOPATHIC TORSION DYSTONIA
DEFINITION:
A slowly-progressing movement disorder characterized by dystonia
and tremor.
EPIDEMIOLOGY:
- incidence: ?
- age of onset:
- risk factors:
- familial - autosomal recessive and autosomal dominant forms
with a 15% new mutation rate
- 5-10x more common among Ashkenazi Jews
PATHOGENESIS:
- also called Dystonia Muscularum Deformans
- the Idiopathic Torsion Dystonia (ITD) gene has been mapped
to chromosome 9q32-34 (Ozelius et al., Neuron 2: 1427-1434,
1989; Kramer et al., Ann. Neurol. 27: 114-120, 1990)
- all three forms of inherited dystonia have had their disease
locus genetically mapped
- Idiopathic Torsion Dystonia - 9q32-34
- Dopa-Responsive Dystonia - 14q
- X-linked Dystonia-Parkinsonism - Xq21
CLINICAL FEATURES:
- focal and intermittent involvement of a lower limb
- usually presents when stressed or during an activity such
as running
- foot may also be extended and rotated causing intermittent
unilateral tip-toe walking
2. Late - Generalized Dystonia
- involvement of all 4 limbs, axial musculature, and muscles
of the face and tongue (impaired speech and swallowing)
- extent of muscle involvement highly variable
- poorer prognosis with younger onset
- dystonic tremor
- an associated symptom
- increases in amplitude when patient attempts to resist
dystonic movements or abnormal posture
- also see "Dystonic Disorders"
INVESTIGATIONS:
- abnormalities in the basal ganglia (putamen)
2. PET
- loss of dopaminergic input to the putamen with sparing of
the caudate input
MANAGEMENT:
- an anticholinergic agent
- start at 1 mg po qhs and increase to 12 mg po od over 4
weeks
- side effects: urinary retention, blurred vision, mental
confusion, drowsiness, memory difficulties, hallucinations
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Pediatric Database - IDIOPATHIC TORSION DYSTONIA
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