Objective: Evaluate the occurrence of sensory disorders (SD) in Idiopathic Parkinson’s disease (IPD) and the impact of treatment in developing peripheral neuropathy (PN).

Background: SD are often overlooked non-motor symptoms (NMS) of IPD despite their prevalence. Various etiologies can be found, one of which is PN.

Method: We conducted an observational study on patients aged over 18 years old who were diagnosed with IPD between 2016 and 2017. Two groups were defined; a first group of 30 patients who did not receive levodopa or did for less than 3 years (G1) and a second group of 30 patients who received it for over three years (G2). We evaluated small fiber (SF) and large fiber (LF) damage.

Results: The median age of 60 patients was 62.92 years old with sex ratio 1,06. Sensory disorders were the most common NMS found (90%). Patients reported deep pain and tingling (18.3% respectively), numbness (33.3%), throbbing pain (3.3%) and burning sensation (16.66%). All patients had SF neuropathy (SFN) with a pathological Neuropad test in 76.6%. Pathological EMLA test (86.6%) was negatively correlated with age at onset and NTSS-6 (p= 0.000 for both parameters). These tests were statistically correlated with UPDRS motor scale and Hoehn and Yahr scale. 53 patients had a pathological sympathetic skin response(SSR). Only SSR latency was negatively correlated with cumulative Levodopa dose (CLD)(p=0.014). A reduction in heart rate variability(23.3%) was correlated with an early age at onset(p= ,138), long disease duration(p= ,130) and an elevated NTSS-6(p= ,958). 26 patients, who were significantly older(p=0.024), had LF neuropathy(LFN). These results didn’t show any significant difference between groups, unlike the median number of pathological tests for SF damage(p= 0.019).

Conclusion: SFN was noted in all 60 patients in our study regardless of the duration or CLD received suggesting that it is an intrinsic feature of the disease. Some studies report alpha-synuclein accumulation on neurons causing interference with axonal transport, which was not present in other parkinsonian syndromes. For SFN, correlation was noted with disease severity and early age at onset and only SSR was correlated with CLD. As for LFN, sural conduction parameters did not show any correlation with neither CLD nor disease duration. Only early age at onset was noted as a potential risk factor for developing LFN.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/idiopathic-parkinsons-disease-and-sensory-disorders-a-complication-of-dopatherpy-or-an-intrinsic-feature-of-the-disease/