61. Patients with progressive supranuclear palsy show abnormal response to conditioned and unconditioned TMS stimuli compared to patients with Parkinson’s disease and healthy subjects

Progressive supranuclear palsy-PSP is the second most common parkinsonian syndrome after Parkinson’s disease-PD, with some overlapping clinical features in the early phases. Non-invasive neurophysiological techniques, such as transcranial magnetic stimulation-TMS, could be useful for the differential diagnosis. Seventeen PD, 13 PSP and 11 healthy controls-HC subjects were included in this study. TMS evaluation included resting motor threshold-RMT, motor evoked potentials-MEP amplitude and latency, response to inhibitory-SICI and facilitating-ICF conditioned stimuli, cortical silent period-CSP, and ipsilateral silent period-iSP. Statistical analysis was performed using either parametric or non-parametric ANOVA according to data distribution. PSP and PD groups did not significantly differ in UPDRS. TMS assessment showed different distribution of RMT across the groups (p.008), with PSP patients showing the highest values and PD the lowest (PSP vs PD p.002). Group also affected iSP duration (p.016), being longest in PSP and lowest in HC (PSP vs HC p.005). On paired-pulse inhibition and facilitation, a significant effect for ISI ( p