The concept of symptomatic or secondary dystonia, as opposed to primary or idiopathic dystonia, emerged in the medical literature as a class of dystonias of known etiology. Perinatal brain injury was the most representative cause of symptomatic dystonia. More recently, different focal brain lesions, neurodegenerations, metabolic disorders of the nervous system, and drugs and chemicals have been recognized as causes of dystonia.
As opposed to primary dystonia, secondary dystonia is considered to be “often accompanied by other neurological deficits,”1,2 to “begin suddenly at rest and occur at rest from the onset,”3 and to be associated with different known hereditary and environmental causes.4 (Table 31–1) These differential criteria are relative since there is a great clinical diversity of secondary dystonias. This chapter discusses the dystonic syndromes secondary to focal, degenerative, metabolic, or chemical insult to the nervous system as well as the pseudodystonias of organic and psychogenic origin. The main clinical characteristics of secondary dystonia, as well as clues for the differential diagnosis, are summarized in Tables 31–2 and 31–3.
Table 31–1. Etiologic Classification of Secondary Dystonia |Favorite Table|Download (.pdf)
Table 31–1. Etiologic Classification of Secondary Dystonia
Caused by focal brain lesions
Associated with degeneration of the central nervous system
Resulting from metabolic disorders of the central nervous system
Produced by drugs and chemicals
Table 31–2. Differential Diagnosis of Symptomatic Dystonias |Favorite Table|Download (.pdf)
Table 31–2. Differential Diagnosis of Symptomatic Dystonias
|Disease||Inheritance||Type of Dystonia||Age at Onset||Clinical Findings||Neuroimaging||Diagnosis|
|Focal brain lesions||Sporadic||Hemidystonia, focal||Children, young adults||Corticospinal and brain stem signs||Focal lesion||Clinical/MRI|
|PD||Mostly sporadic||Focal||Adults||Tremor, ARS||Normal (nigral T2 shortening)||Clinical|
|PSP||Mostly sporadic||Axial||Mature senile||Gaze palsy, ARS||Midbrain tectal atrophy||Clinicopathological|
|CBD||Sporadic||Limb||Mature senile||Apraxia, myoclonus, alien limb||Asymmetric cerebral atrophy||Clinicopathological|
|MSA||Sporadic||Axial||Mature senile||ARS, autonomic, cerebellar||OPCA, T2 putaminal hypointensity in SDS and SND||Pathology|
|Huntington's disease||AD||Generalized||Young adults||Chorea, dementia||Caudate and cortical atrophy||Genetic, IT15 CAG expansion|
|Neuroacanthocytosis||AR sporadic||Orolingual, generalized||Young adults||Chorea, amyotrophy, epilepsy||Caudate atrophy||Acanthocytes|
|Wilson's disease||AR||Generalized||Children, young adults||Tremor, psychiatric, dysarthria||Putaminal, thalamic dentate, brain stem, T2 high signal||K-F rings, Cu2+ levels, ceruloplasmin gene defects of chromosome 13|
|Neurodegeneration with brain iron accumulation||AR||Multifocal, generalized||Children, young adults||Corticospinal, dementia||Pallidal T2 hypointensity (“eye of the tiger” sign)||Pathology|
|Fahr's syndrome||AD/AR/sporadic||Generalized hemidystonia||Adults||ARS, corticospinal, ataxia, dementia||Basal ganglia striking calcifications||Imaging (exclusion diagnosis)|
|Ataxia telangiectasia||AR||Generalized||Children||Ataxia, neuropathy||Cerebellar atrophy||Clinical, low levels IgA|
|Machado-Joseph||AD||Multifocal, generalized||Children, young adults||Ataxia, ophthalmoplegia, amyotrophy||Cerebellar atrophy||Genetic, CAG expansion 14q|
|Dentatorubro-pallidoluysian atrophy||AD||Generalized||Adults||Ataxia, dementia, myoclonus||Brain stem, cerebellum Alt signal||Genetic, CAG expansion 21p...|
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