Applause sign helps to discriminate PSP from FTD and PD

The applause sign is a simple test of motor control that helps to differentiate PSP from frontal or striatofrontal degenerative diseases. It was found in 0/39 controls, 0 of 24 patients with frontotemporal dementia (FTD), 0 of 17 patients with Parkinson disease ( PD), and 30/42 patients with progressive supranuclear palsy (PSP). It discriminated PSP from FTD (p < 0.001) and PD (p < 0.00). The three clap test correctly identified 81.8% of the patients in the comparison PSP and FTD and 75% of the patients in the comparison of PSP and PD.