Objective: Present a SCA10 patient presenting with rare phenomenology of dystonia in addition to ataxia.

Background: The spinocerebellar ataxias (SCAs) are a heterogenous group of neurodegenerative ataxic disorders, typically autosomal dominant. Prevalence of SCA subtypes varies depending on geographic location and ethnic distributions. SCA10 been described exclusively in Latin American patients with at least partial Amerindian heritage. There is considerable phenotypic variability in SCA10, but patients classically exhibit cerebellar ataxia and epilepsy, with few other consistent exam findings. SCA10 is caused by a repeat expansion (ATTCT) in ATXN10 gene: normal alleles contain ~10-29 repeats, pathologic alleles contain 800-4500 repeats; anticipation is typically observed. SCA10 has been described in case reports of families in Mexico, Brazil, Argentina, and Venezuela. While cerebellar ataxia is seen in all affected patients, other features are variable. Epilepsy, while present in over 70% of affected members of large Mexican families studied by Grewal et al., was only present in 3.75% of Brazilian patients described by Teive et al. Pyramidal signs such as hyperreflexia and spasticity are occasionally seen. In the Argentine family described by Gatto et al., two patients exhibited extrapyramidal signs: akinetic rigid parkinsonism in one individual and laterocollis in another family member – the only previously documented case of dystonia in SCA10.

Method: –

Results: A woman in her 30s with Ehlers-Danlos Syndrome and epileptic- and non-epileptic seizures presented with progressive imbalance which began at age ~20. A, when a few months after giving birth, she began experiencing unsteady gait and extremity paresthesias. At age 37, she developed involuntary movements: jaw closure, head turning and neck spasms, right foot dorsiflexion and toe extension, consistent with multifocal dystonia. Her exam also revealed end-point tremor bilaterally, dysdiadochokinesia of the left hand, dysmetria of the lower extremities bilaterally; gait was normal (Video 1). Her ancestry was Colombian and Middle Eastern. Genetic testing showed a repeat expansion in ATXN10 of 2011 and 14 repeats, consistent with SCA10.

Conclusion: This case of a 37-year-old woman with genetically confirmed SCA10 who was found to have multifocal dystonia affecting her neck, jaw, and bilateral lower extremities, is to our knowledge, the second documented instance of dystonia in a patient with SCA10 in the literature.

References: Gatto EM, Gao R, White MC, et al. Ethnic origin and extrapyramidal signs in an Argentinean spinocerebellar ataxia type 10 family. Neurology. 2007;69(2):216-218. doi:10.1212/01.wnl.0000265596.72492.89

Matsuura T, Yamagata T, Burgess DL, et al. Large expansion of the ATTCT pentanucleotide repeat in spinocerebellar ataxia type 10. Nat Genet. 2000;26(2):191-194. doi:10.1038/79911

Matsuura T, Ashizawa T. Spinocerebellar Ataxia Type 10. In: Adam MP, Feldman J, Mirzaa GM, et al., eds. GeneReviews®. Seattle (WA): University of Washington, Seattle; April 23, 2002.

Teive HA, Roa BB, Raskin S, et al. Clinical phenotype of Brazilian families with spinocerebellar ataxia 10. Neurology. 2004;63(8):1509-1512. doi:10.1212/01.wnl.0000142109.62056.57

Teive HA, Munhoz RP, Raskin S, et al. Spinocerebellar ataxia type 10: Frequency of epilepsy in a large sample of Brazilian patients. Mov Disord. 2010;25(16):2875-2878. doi:10.1002/mds.23324

Teive HA, Munhoz RP, Arruda WO, Raskin S, Werneck LC, Ashizawa T. Spinocerebellar ataxia type 10 – A review. Parkinsonism Relat Disord. 2011;17(9):655-661. doi:10.1016/j.parkreldis.2011.04.001

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