Dopamine-transporter imaging and visuo-motor testing in essential tremor, practical possibilities for detection of early stage Parkinson's disease

Abstract

Background. Essential tremor (ET) is often an alternative diagnosis to Parkinson's disease (PD) and some ET patients may later develop PD. Unlike the former, PD patients have deficient visuo-motor coordination (VMC). Recently, we have attempted to exploit this difference in order to detect PD in ambiguous neurological cases. Objective. To assess the possibility of using VMC testing for screening ET patients prior to [123I]-FP-CIT SPECT imaging. Methods. Ten clinically diagnosed ET patients who showed deficient VMC were subjected to [123I-FP-CIT] SPECT imaging. We expected these patients to show subnormal striatal ligand uptake, as in PD. Results. We found decreased [123I]-FP-CIT uptake in 80% of the patients. A significant correlation between ligand uptake and VMC was observed. Conclusions. Impaired VMC is a pertinent indication for further SPECT imaging in patients with ET, in order to establish a diagnosis of incipient PD.