Striatal dopamine function in a family with multiple SCA-3 phenotypes.

We present single photon emission computed tomography (SPECT) studies using 123IFP-CIT (DAT scan) and 123I-IBZM imaging, performed on four members of a family with genetically proven spinocerebellar ataxia type 3 (SCA-3). DAT scan showed significant asymmetric decreased binding in the striatum in the two members with predominant parkinsonian phenotype, with mild and symmetric decreased binding in the member with the cerebellar phenotype, and normal in the asymptomatic member. The IBZM SPECT studies showed mild and asymmetrical reduction of the striatal dopamine D2 receptor density (parkinsonian members). SCA-3 can present with a levodopa responsive parkinsonism phenotype, and an abnormal DAT scan showing predominant impairment of presynaptic dopamine function.