Investigation of changes in the sympathetic skin response to levodopa therapy in patients with Parkinson's disease.

Background and purpose: We sought to evaluate the acute and dynamic alterations in the sympathetic skin response (SSR) in patients with Parkinson's disease (PD) in response to levodopa therapy.

Methods: We studied patients who were diagnosed with PD in our movement disorders clinic between January 2023 and May 2023. In addition to demographic and clinical features, the levodopa equivalent dose, nonmotor symptoms scale score, and Movement Disorders Society-Unified Parkinson's Disease Rating Scale score were evaluated. SSRs were studied during the medication-ON and medication-OFF periods by a trained neurophysiologist.

Results: Overall, 22 patients with PD were enrolled in the study. The mean age of the patients was 59 ± 8.1 y. The correlation analyses between the clinical features and SSR parameters revealed only a moderate positive correlation between age and the latency of the SSR (left side). Repeated analysis of covariance revealed that the latencies of the SSR were shortened bilaterally in the medication-ON group (right, p=0.012; left, p=0.012).

Conclusion: We found electrophysiological evidence regarding the corrective effect of levodopa on autonomic dysfunction (AD) in PD patients. An investigation of the possible levodopa response of the clinical features related to AD might contribute to the unknown pathomechanisms of AD in PD patients.