SCA2 presenting as a focal dystonia
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CASE REPORT
Open Access
SCA2 presenting as a focal dystonia Nan Cheng1* , Heather M. Wied2, James J. Gaul3, Lauren E. Doyle4 and Stephen G. Reich1
Abstract Background: Spinocerebellar ataxia 2 (SCA2) is an autosomal dominant neurodegenerative disorder caused by CAG repeat expansions in ATXN2 on chromosome 12q24. Patients present with adult-onset progressive gait ataxia, slow saccades, nystagmus, dysarthria and peripheral neuropathy. Dystonia is known to occur as SCA2 advances, but is rarely the presenting symptom. Case presentation: A 43-year-old right handed woman presented with focal dystonia of the right hand which started two years earlier with difficulty writing. There were only mild cerebellar signs. Her mother was reported to have a progressive gait disorder and we subsequently learned that she had SCA2. A total of 10 maternal family members were similarly affected. Over the course of 10 years, the patient’s cerebellar signs progressed only mildly however the dystonia worsened to the extent of inability to use her right hand. Dystonia did not improve significantly with botulinum toxin, levodopa or trihexyphenidyl, but has shown marked improvement since DBS implantation in the GPi. Conclusions: We describe a patient with SCA2 who presented with focal dystonia of the right upper extremity. Subtle cerebellar signs as well as the family history became especially important given the absence of predominant gait ataxia. Our case emphasizes that focal dystonia is not only a feature of SCA2, but can also rarely be the presenting sign as well as the most prominent feature during the disease course. Keywords: Spinocerebellar Ataxia 2, SCA2, Dystonia, Deep brain stimulation
Background The spinocerebellar ataxias (SCAs) are a group of inherited neurodegenerative disorders that encompass a broad range of neurologic signs. SCAs are characterized prominently by cerebellar ataxia along with variable oculomotor abnormalities, pyramidal and extrapyramidal features (EPS), dementia and peripheral neuropathy [1]. There are over 44 distinct subtypes of SCAs [2], with the more prevalent types – SCA1, SCA2, SCA3 and SCA6 – caused by autosomal dominant CAG repeat expansions in polyglutamine encoding genes [3]. SCA2 is caused by repeat expansions in the ataxin-2 gene on chromosome 12q24. Neuropathologically, SCA2 is characterized by cerebellar and brainstem atrophy, as well as basal ganglia, thalamic, spinal cord and peripheral nerve degeneration [4] [5]. As with all the SCAs, the clinical hallmark and presenting sign is a progressive cerebellar syndrome. Associated clinical features include * Correspondence: [email protected] 1 Department of Neurology, University of Maryland School of Medicine, Baltimore, MD, USA Full list of author information is available at the end of the article
slow saccades, muscle cramps and peripheral neuropathy. Less commonly, patients can present with extra-pyramidal signs (EPS) such as levodopa responsive or atypical parkinsonism [6], REM sleep behavior disorder and dystonia [7]; however the
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