Can loss of the swallow tail sign help distinguish between Parkinson Disease and the Parkinson-Plus syndromes?

Purpose: To determine if loss of the swallow tail sign (STS) can distinguish Parkinson Disease (PD) from the Parkinson-Plus syndromes.

Methods: Twenty-five patients with PD, 21 with Parkinson-Plus syndromes, and 14 control patients were included. Presence of the STS was assessed.