Nolano M, et al. – This study strived to investigate small and large fiber pathology in drug–naive and L–dopa–treated patients affected by Parkinson's disease (PD) in early phases, before the occurrence of neuropathic electrophysiologic abnormalities. In the early stages of PD, both large and small fiber pathology occurred and could account for the sensory and autonomic impairment. L–Dopa affected the 2 populations of fibers differently.