Patients with small fiber neuropathy exhibit more pronounced non-motor symptoms in Parkinson's disease

Background Peripheral neuropathy in Parkinson's disease (PD) may not be an isolated pathological phenomenon but may interact with other non-motor symptoms. Objective To conduct a comprehensive investigation of the non-motor symptoms observed in PD patients, with a comparative analysis between patients with and without peripheral neuropathy, to explore the relationships between peripheral neuropathy and non-motor symptoms. Methods 100 PD patients were recruited from the Neurology Department of Guangdong Provincial People's Hospital. Extensive clinical data were collected, and assessments were performed to evaluate both motor and non-motor symptoms in patients with and without peripheral neuropathy. Spearman's rank correlation analysis was employed to evaluate the association between peripheral neuropathy and non-motor symptoms. Multiple linear regression analysis was conducted to adjust for confounding variables to clarify the impact of peripheral neuropathy on non-motor symptoms. Results 57 individuals (57%) were identified as having peripheral neuropathy. Of these, 38 individuals were diagnosed with small fiber neuropathy. After adjusting for confounding variables, higher scores on the 13-item Small Fiber Neuropathy Symptom Inventory Questionnaire were significantly correlated with heightened symptoms of depression (B = 0.498, 95% CI = 0.080–0.917, p = 0.020), anxiety (B = 0.504, 95% CI = 0.099–0.908, p = 0.015), autonomic dysfunction (B = 1.118, 95% CI = 0.828–1.409, p < 0.001), and sleep disturbances (B = 0.694, 95% CI = 0.309–1.080, p = 0.001). Conclusions PD patients with neuropathy, particularly those with small fiber neuropathy, demonstrate more pronounced non-motor symptoms. The severity of small fiber neuropathy is correlated with the extent of depression, anxiety, autonomic dysfunction, and sleep disturbances. These findings underscore the necessity for routine screening and early detection of peripheral neuropathy in PD patients.