Analysis of Heart Rate Variability in Functional Movement Disorder Patients (P3.008)

Abstract

Objective: To assess heart rate variability, a biomarker of central autonomic function, in patients with functional movement disorders (FMD) compared to healthy controls. Background: Autonomic activity is of interest in FMD patients given the hypothesis that the abnormal movements seen in FMD are in part the result of converted psychological stress and increased vulnerability to emotional reactivity. Studies have shown that the autonomic nervous system participates in regulation of emotion. Heart rate variability (HRV) provides a quantitative assessment of central autonomic activity. Reduced HRV can be reflective of autonomic dysregulation, with decreased parasympathetic input relative to sympathetic input. While reduced HRV has been demonstrated in a variety of mood and anxiety disorders, autonomic regulation has not been well studied in the conversion disorder population. Design/Methods: “Clinically definite” FMD patients and age- and gender-matched healthy controls were hospitalized overnight for continuous electrocardiogram (ECG) recording. ECG data was analyzed using Impresario software, artifacts were removed, and data was imported into Matlab for calculation of multiple HRV time and frequency domain measures. HRV parameters analyzed included standard deviation of the N-N interval (SDNN), and power spectral density analysis in very low frequency (VLF), low frequency (LF) and high frequency (HF) ranges. Patients on heart rate altering medications or with history of cardiovascular disease were excluded. Results: 33 FMD patients and 35 healthy controls were assessed in this ongoing project. FMD patients demonstrated reduced HRV, as determined by significantly diminished daytime SDNN (p=0.04) and daytime VLF (p=0.04). FMD patients also showed increased index of sympathetic to parasympathetic activity compared to healthy controls, as indicated by significantly increased nighttime LF/HF ratio (p=0.03). Conclusions: Alterations in regulation of the autonomic nervous system may play a significant role in the pathophysiology of FMD, and merit further exploration.

Disclosure: Dr. Liu has nothing to disclose. Dr. Maurer has nothing to disclose. Dr. LaFaver has nothing to disclose. Dr. Toledo has nothing to disclose. Dr. Hallett has received personal compensation for activities with Neurotoxin Institute, Cambridge University Press, Oxford University Press, Wiley-Blackwell, and Springer.