A movement disorder that manifests in childhood and
advances to total incapacitation within a few years.
Primary Dystonia; Idiopathic Torsion Dystonia; Dystonia
Musculorum Deformans (Early Onset Primary Torsion Dystonia);
Ziehen-Oppenheim Disease; Ziehen-Schwalbe-Oppenheim Syndrome.
First described in 1908 by S. Schwalbe in a Jewish family and in
1911, Oppenheim termed this condition as dystonia musculorum deformans (DMD).
About 10 to 15:100,000 live births. A female
predilection has been reported for focal and segmental primary torsion
dystonia. Primary Torsion Dystonia is more common among the Ashkenazi Jewish
For both early-onset and late-onset primary
torsion dystonia, transmission is autosomal dominant with a low penetrance;
for the early form, it is 30 to 40% penetrance, and for late-onset
primary torsion dystonia, it is even lower at 10 to 15% penetrance.
Negative family history does not exclude the diagnosis. The mutation for the
early form has been mapped to 9q34, identified as a GAG deletion and called
DYT1 gene. The resulting protein, torsinA, is an ATP-binding protein with
some similarities to the heat-shock protein superfamily. The mutation of the
late-onset primary torsion dystonia has been mapped to 8p21-q22 (DYT 6 gene)
and to 18p (DYT 7 gene).
Unknown. However, it has been hypothesized that
the dystonic movements originate from a functional disturbance of the basal
ganglia (most likely because of an increased striatal inhibition on globus
pallidum and substantia nigra) in combination with a severely altered
pattern of normal spontaneous neuronal activity. This may affect the thalamic
control on planning and execution of movements, as well as brainstem and
spinal inhibitory reflexes, and result in the dystonic pattern of
pathological cocontraction of agonist and antagonist muscles with abnormal
recruitment of more extraneous muscle groups (as seen in the EMG).
The diagnosis is mainly based on clinical findings of
involuntary movements. So far, neuroimaging studies (CT, MRI scans),
postmortem examinations, and laboratory studies have not revealed any
pathological findings in primary torsion dystonia. Perinatal asphyxia is the
most common cause for secondary dystonia in children, and among other causes
with similar symptoms such as encephalitis, traumatic brain injury,
neurotoxins, and drugs, has to be ruled out. Its onset is usually—but not
always—in the first 3 years of life. In primary torsion dystonia, most
patients are and remain mentally normal; however, patients with severe
developmental delay have also been described.
The hallmark of primary torsion dystonia is
sustained muscle contractions that often result in twisting, repetitive
movements, and/or abnormal postures. Depending on the anatomical sites that
are affected by the dystonic movements, primary dystonia can be divided in
focal (only one anatomical site, e.g., neck, eyelids, mouth, larynx, hand),
multifocal (several, noncontiguous anatomical sites), segmental (contiguous
anatomical sites), hemidystonic (limited to one body side), and generalized
(leg in combination with other body sites) primary torsion dystonia.
Generalized primary torsion dystonia is the most common form in children,
whereas the focal and the ...