Preclinical impairment of the striatal dopamine transporter system in sporadic olivopontocerebellar atrophy: Studied with [I-123]beta-CIT and SPECT

We investigated whether the dopamine (DA) transporter system is impaired in sporadic olivopontocerebellar atrophy (sOPCA) patients without clinical pa rkinsonism using the DA transporter radiotracer [I-123]beta-CIT [2 beta-car boxymethoxy-3 beta-(4-iodophenyl)tropane] and single-photon emission comput ed tomography (SPECT). SPECT scans were acquired in 9 patients with sOPCA, 7 multiple system atrophy (MSA) patients with parkinsonism (MSA-P), and 7 a ge-matched healthy controls 20-24 h after the intravenous injection of [I-1 23]beta-CIT. [I-123]beta- CIT-specific binding in the striatum was determin ed as the radioactivity ratio of the striatum to the occipital cortex (spec ific binding ratio, SBR). In patients with sOPCA and MSA-P, SBRs in the rig ht and left striatum and the mean SBR were significantly lower than those i n controls (p < 0.05), The mean SBRs in patients with sOPCA and MSA-P were reduced to 69.0 and 60.7% of the control mean, respectively. However, there was no significant difference in SBRs between sOPCA and MSA-P patients. In sOPCA patients, the mean SBR was significantly correlated with the score o f the clinical cerebellar function scale (r = -0.670, p = 0.024). These res ults indicate that even in the absence of clinical parkinsonism, the striat al dopaminergic system may be impaired in sOPCA. The DA transporter loss in sOPCA serves as another clue for sOPCA being a part of the spectrum of MSA , Copyright (C) 2000 S.Karger AG, Basel.