Correlates of polyneuropathy in Parkinson’s disease

Abstract

Objective: Previous studies in Parkinson's disease (PD) patients have demonstrated a high prevalence of polyneuropathy (PNP) and pronounced alpha-Synuclein pathology in dermal nerve fibers already at early disease stages. The aim of this study was to analyze associations between the prevalence and severity of PNP with nonmotor and motor symptoms in PD patients. Methods: Fifty PD patients were characterized comprehensively for the presence of clinical symptoms (nonmotor and motor), electrophysiologic alterations andfor the first timeusing high-resolution ultrasound of peripheral nerves. Results: Sixty-two percent of PD patients showed electrophysiological pathology of PNP. The prevalence of patient-reported PNP symptoms was 86% and was particularly present in patients with longer disease duration, compromised scores of nonmotor and motor symptoms as well as with a negative evaluation of quality of life. Seventy-five percent of patients showed morphologic alterations similar to axonal PNP in high-resolution ultrasound compared to healthy controls. Interpretation: The study demonstrates the high burden of peripheral nervous system disease in Parkinson's disease. It advocates further studies to delineate the underlying pathophysiological mechanisms in order to optimize treatment approaches for PD, including the associated PNP.

Prevalence and Characteristics of Polyneuropathy in Atypical Parkinsonian Syndromes: An Explorative Study

“…In the present study, high levels of subjective neuropathic complaints in 87.5% of the MSA and 66.7% of the PSP patients were recorded by the patient self-report instrument NSS. Electrophysiological confirmation of PNP could be established in 50% of the MSA and 50% of the PSP patients, which considerably exceeds the rate of 7-9% in the normal elderly population [32,33], but is consistent with the reported PNP prevalence rates in PD, ranging from 16.3% up to 62% [9,34].…”

“…While NSS in PD patients significantly correlated with motor, non-motor symptoms as well as poor quality of life in our study, we found a significant correlation between NSS and UPDRS part III in PSP patients, including within the subscales of midline function and lower limb bradykinesia. Regarding electrophysiological alterations, Kühn et al reported a correlation between motor nerve amplitudes in PD patients and motor impairment, disease duration and age [9]. Lower tibial cMAP amplitude in MSA patients in our study was associated with higher UMSARS II scores as well as UPDRS III scores, including midline function (facial expression, posture, gait) and lower limb bradykinesia.…”

“…In the "Parkinson Nerve Study" by Kühn et al, 86% of PD patients reported PNP symptoms, and a higher proportion of PD patients (62%) showed electrophysiological signs of PNP compared to our MSA and PSP population [9]. Although NSS is higher in PD, the NSS rate of MSA (87.5%) and PSP (66.7%) patients in our study with at least mild neuropathic symptoms (NSS > 2) remains high, compared to a diabetic population where only 48% have an NSS > 2 points [38].…”

“…Non-motor symptoms, including pain, mood, cognition, sleep, gastrointestinal and urogenital disturbances are frequently prevalent and burdensome not only in PD, but also in APS [5,6]. While peripheral nerve involvement has been increasingly recognized in PD [7][8][9][10], only few studies have addressed peripheral nerve alterations in APS thus far. The prevalence of peripheral nerve abnormalities detected by nerve conduction studies is estimated up to 40% [11][12][13].…”

“…In order to expand the knowledge on peripheral nerve involvement in APS, we aimed to analyze the frequency, clinical, electrophysiological and morphological characteristics of polyneuropathy (PNP) associated with MSA and PSP. Therefore, we applied the "Parkinson Nerve Study" design, which has been established in Parkinson's disease [9], to explore the relevance of PNP in APS.…”