Sensory neuropathic symptoms in idiopathic Parkinson's disease: prevalence and impact on quality of life

Neuropathic symptoms are commonly reported in Parkinson's disease (PD), but robust data on the epidemiology of such symptoms are lacking. The present study sought to investigate the prevalence and determinants of peripheral sensory neuropathic symptoms (PSNS) in idiopathic PD (IPD) and ascertain the effects of such symptoms on the patients' quality of life (QoL). Patients with IPD and age-matched and gender-matched controls were screened for neuropathic symptoms using the Michigan Neuropathy Screening Instrument. The impact of neuropathic symptoms on QoL was investigated using the 36-Item Short Form Survey. Fifty-two patients and 52 age-matched and gender-matched controls were recruited. PSNS were reported more frequently in patients with IPD than in the control subjects (57.7 versus 28.8%, p = 0.003). No significant relationships were found between PD-related clinical characteristics (i.e. disease severity and duration, duration of exposure to levodopa) and the presence of PSNS. Significant correlations were found between the number of PSNS and physical functioning (Spearman's Rho - 0.351), even after adjusting for age, gender and Hoehn and Yahr score. Our results support the notion of a greater prevalence of PSNS in IPD patients as compared to the general population, which, at least in part, may be secondary to large and/or small fibre peripheral neuropathy. This warrants further investigation in larger studies that include detailed neurophysiological assessments.