Intraindividual Variability of Nonmotor Fluctuations in Advanced Parkinson's Disease.

Nonmotor symptoms (NMS) fluctuate in conjunction with motor oscillations in advanced Parkinson's disease (PD), though little is known about the variability of NMS fluctuations in individual patients. We aimed to assess within-patient variability in frequency and severity of NMS during a series of five patient-perceived motor On and Off periods in 38 fluctuating PD patients from the multicenter NonMotorFluctuations in PD study using a visual analogue scale. NMS frequency and severity appeared moderately variable in both motor states within individual patients. Symptom severity ranges between motor states showed high variability and were larger in motor Off states for most NMS.